YouTube Transcript:
Python Full Course For Data Engineers [6+ HOURS]

Skip watching entire videos - get the full transcript, search for keywords, and copy with one click.

Video Transcript

Video Summary

Summary

Core Theme

This comprehensive Python masterclass is designed for aspiring data engineers, covering essential Python concepts and their practical applications in the data engineering domain, with a focus on interview preparation and real-world scenarios.

Mind Map

Click to expand

Click to explore the full interactive mind map • Zoom, pan, and navigate

In this 6 hours long Python master class

for data engineers will cover Python

variables, data structures, list

comprehension, conditionals in Python,

iterables and infinite loop, dynamic

functions, lambda functions, classes and

objects, static and instance methods,

exception handling in Python, single

level, multi-level and multiple

inheritance, getters and setters in

Python, request module to fetch API

data, parallel processing using

multi-threading and much more Python is

the most important skill that you have

to master if you want to crack data

engineering interviews and you know what

Python is widely used in so many domains

and you need to understand what to cover

and what not to cover. So that is why

this complete guide will tell you

everything you need to know for data

engineering and do you know the best

part this course has covered realtime

scenarios that are strongly aligned to

data engineering directly. So if you

want to master Python and want to crack

multiple data engineering offer letters

in 2025, then let's get started with

this amazing

video. So what's up? What's up? What's

up my data fam? Happy Sunday. And

finally, finally this video is here. Uh

or I would say this master class is

here. This masterpiece is here. I

received so many requests for this

video. Python, Python, Python and I can

say that in today's era, Python has

become much more important and if we

just talk about data engineering domain,

Python is the I would say only

programming language that you should

learn as your like top priority. You

will say Scala is also there, Java is

also there, blah blah is also there.

Python will be at the top. Will be at

the top and is is on the top. So basically,

basically,

Python is such a wide programming

language. So that means they have so

many use cases. Python is widely used in

so many other domains as well such as

software engineering, web development,

data analytics, data science like so

many other domains as well. Right now we

as a data

engineers need to learn Python smartly.

So basically if you are just getting

started with data engineering or even if

you are a data engineer maybe you are

not much familiar with Python concept

that we need to understand from the data

engineering perspective then obviously

this video is for you. If you are

totally a beginner this video is for

you. If you have like you can

say good years of experience till this

video is for you. Why? Because we going

to cover so much amazing stuff in this

video. Let me just give you some hints

for those who are very pro. So we going

to just cover multipprocessing, multi-

threading and all. So now you know like

what I'm talking about. Okay.

So this video will start from zero.

Okay. And this will go like this

exponentially. And the most important

part that you should know about this

video is um obviously Python has so much

to discuss and I would say it is

neverending topic because the moment

you'll be just about to cover all the

topics there'll be a new update new

library new update in the existing

library. So what we going to cover in

this video? You should know the agenda.

We going to cover Python concepts which

are which are the most important

concepts in the data engineing domain

which are

non-negotiables. Obviously we going to

cover much more than that but we will be

purely focusing on Python for data

engineers. Python for data engineers. So

do not say like hey this part is

missing. Hey this topic is missing. No,

we going to cover which are more

important or I would say the most

important non-negoti sorry

non-negotiables for data engineers. Got

it? This is the agenda of this video. So

that is why the title is Python for data

engineers. Make sense? And I know there

are so many tutorials for Python in

YouTube and they are really really

great. I'm not like denying but there

was a need to just create a kind of

master class for Python just for data

engineers like what things you need to

focus more on what things you can just

neglect what things are like little bit

less important from data engineers

perspective what things are like the

most the most the most important now uh

you will be like we are all charged up

an Lamba now obviously we going to learn

Python for data engineer So do we need

any kind of prerequis? The answer is no.

The answer is no. Yes, we'll be starting

from the zero. Yes, we'll be just

leveling up very very very rapidly

because you are a data engineer and you

need to learn the main things instead of

just like devoting more time on those

things which are not directly related to

your domain. Right? We going to learn

multi-threading and all everything.

You'll be like what is multi-threading?

Don't worry, don't worry. Don't worry.

Everything will be crystal clear for

you. And the best part we do not even

need any kind of installment for this

really installment installation sorry we

do not need any kind of installation for

this. Why?

Because we have so many online Python

compilers. So we can easily use those

compilers because this will save you a

lot of time to just get started

immediately because whenever you're

learning something new you do not need

to waste your time in the installation

of something. just get started quickly

so that you will just catch the momentum

right once you have that momentum you

can just install so many things and

that's what we will be also doing so

first of all you will just get started

with the online compiler and at the end

I will just show you some things which

are let me just give you some hints we

will just focus on OS module as well

which is like operating system module in

Python library which is really important

for you as a data engineer so for that

obviously you would need like local

python uh interpreter but that is like

um will be discussed at the end of the

video. Okay. So to get started we going

to use our online Python compiler and

uh you can use any online Python

compiler also like I use like any random

compiler as per the link that I see on

the top that's it because all the Python

compilers are same not compiler because

Python is an interpreter okay so because

it interprets the code like line by line

so you can use like any online Python

interpreter and you will be good okay

there's no you can say Uh I'm not

inclined towards any one or two Python

compiler interpreters. You can use any

one. Okay. So without wasting any time,

let's get started with the Python. And

obviously we going to we not going to

just start with with hey, what is

Python? Hey, who started Python? Hey,

when was Python launch? No, we going to

we we are data engineers. We going to

just get started with the actual thing,

right? Let's get started with Python.

Let's write our first code. Let's see.

In order to get started with any online

Python interpreter or compiler, you

simply need to go on Google and simply

say write online Python compiler, you

will get a lot of links. Okay? And

again, I'm not a fan of any particular

one. I'm just fan of an interpreter or

you can say compiler. So, I will simply

click on the very first link that I'm

getting on the screen. You can also like

click on the any link. Okay? Because all

are just interpreters. You just need to

write the code. You will simply see the

output. That's it. Okay? So I'm simply

click on clicking on this. Okay. Oh,

perfect. This UI is good. Okay. I like

like black UIs for programming. So this

is our interpreter or you can say

compiler. Um again I will just remove

your confusion like what is a compiler

and what is an interpreter like why we

call Python as you can say interpreted

language instead of compiled language.

You will get to know don't worry. So

first of all let me just tell you this

is our compiler. Okay, let's call it as

compiler. You will like why why why is

this different? So basically in other

languages like C, C++ all are like uh we

use compilers to compile that. Okay, so

now this is your area. Okay, here we

will just writing our code. This is the

area where we will just write anything

any program that you want to build. This

is the output. Whatever we will be

writing we will simply say it here.

Simple like parallel screens screens I

like it. So I think it is the perfect

compiler or you can say um interpreter

that we got luckily um like most of them

are like same. So it's up to you. Okay.

So this is the thing and you can see a

lot of languages here JavaScript R HTML.

So we are not covering that. We are just

covering Python. So simply select this.

Maybe you are just selecting this one

and you are saying hey my code is not

working because you are just running R.

So simply click on Python. Okay. And now

you can even switch the colors. I think

this button is for yeah toal light mode.

You can simply pick this. I like black

color. So I will simply pick this one.

So now I can simply expand the screen as

well. Like I think this is for

expansion. Yeah. Enter because lot of

you can say compilers are same. So

simply expand it. Yeah. Perfect. Now our

screen is expanded and this is our area.

Perfect. So basically let's get started

with the code and let's write our first

code. Let me remove everything. I still

remember those days when I started with

Python. Actually uh Python

was you can say a kind of entry point

for the data domain for me and I still

remember those days. Um I started

writing Python on my mobile phone

because I didn't have the laptop at that

time. So what I did I installed a Python

interpreter using Play Store on my

Android mobile and I was simply writing

the code. I was feeling so happy when I

was just seeing the output. I was like

okay okay this is the thing. Then I

think later I attached the keyboard to

my phone and I was just literally

writing the code on my mobile phone and

I think yeah yeah

um that's a long story and I would

prefer sharing that story on TEDex stage

instead of like this. So just wait for

it. Just wait for it. Just wait for it.

You'll get to know everything what

happened, how happened and everything.

Okay. So first of all let me just tell

you the first code that is very popular

code that you will write in Python if

you are learning. Okay. And what is that

code? The code says print command

because you will be just writing

something in any programming language.

Today we are covering Python. So

whatever you want to let's say print or

whatever you want to display to your

customer or even to yourself. So we have

a function called print or you can say

we have a command called print. Now when

you write print you need to just use

these braces and within this whatever

you want to print let's say I want to

print a string called hello world which

is very popular in all the programming

languages but today we'll be just

printing hello anal lamba or you can

simply pick your name as well. So how we

can just do that for string? Obviously

uh we know that we need to simply

encapsulate it in the double quotes. So

we will simply do that and I will simply

say hello anal

lamba. So this is the thing whatever I'm

writing within this print command it

will be displayed on the output. It will

be displayed on the screen to the user.

Simple. So let me just click on

run. Oh perfect. You can see that hello

an Lamba whatever I put it here in the

print command it is here and it is

saying code execution successful which

is just a kind of log that you are

getting. Okay, this is super super super

useful. Now let me just write one more

print command. Okay, let's say I want to say

say print

print [Music]

[Music]

hello. Okay, let me just run this. So

what it will do? It will first execute

this one and this one. Really? No. So

basically whatever you write in this

area, this will be treated as one

program or you can say one py file

because the extension is py for python

file. So it will be treated as only one

py file. And you want to see what is the

name of that py file. It is called main.

py. Who created it? Not us. it is

already there by the online compiler. So

whatever we are writing here behind the

scenes it is running our main py like

this. So whenever we go to terminal we

simply write uh python then we simply

give the location of that file. Okay the

full path and if you're just running

from the existing directory you can

simply name it like main. py make sense.

So you can simply provide this thing. So

behind the scene whenever I just click

on run button it is doing this thing and

it is giving me the results. So whatever

I'm writing it here in py file I am just

seeing it here on the parallel screen.

When you install this particular you can

say setup on your local machine. You

will see the same stuff but you do not

need to every time say hey python

main.py because we rarely use terminal

to run our python scripts. We simply use

run command that we get with the help of

any code editor. What is the most

popular code editor? VS code editor.

Okay, I love VS code. So we see the

similar U user interface there as well.

But you should also know the basic

stuff. It is like if you just want to

run the Python script from the terminal,

you can simply write something like

this. Python and then main.py. It will

simply run your Python script. Make

sense? Make sense? Makes sense. Now let

me just tell you like how our code is

being interpreted. Let me just tell

you happens when you run a Python

script. Okay, this is like very

fundamental knowledge and you should

have this knowledge. So there are

basically two steps involved. Okay, the

first step is whatever we write in the

code, it will be first compiled to pite

code. But Anlama, you said like it is

not a compiled language. Yeah, but not

completely. Basically whenever we run a

Python file or you can say py file

python first compiles the entire script

entire script that means whole dot main

like main py okay into an intermediate

form called byte code. So it will be

converted into byte code the whole code

the whole script. Then that bite code

will go to the Python virtual machine or

you can just take it as a kind of uh

interpreter. Okay, Python interpreter.

Then the bite code is executed line by

line. It will not be executed like the

whole code. It will be executed line by

line. This part happens during runtime.

This is why Python is considered as an

interpreted language because it will be

interpreted line by line the whole byte

code. But yes, it will be compiled to

the bite code first. Make sense? Make

sense? Whereas in the other languages

C++ C, it is not an interpreted

language. It will be simply converted

into bite code and then into the machine

code. Make sense? That is why those are

like pretty much faster. But yeah,

Python is very much popular and Python

is performant. Python is reliable.

Python is taking over like with like it

is like well integrated with all the

modern AI tools and everything. So that

is why but C++ C those are pretty much

fast very fast like because it is

directly converting the code into

machine code and they are just running

locally they do not need any kind of

interpreter and all they are really

really fast they are really fast that's

why in the data engineering space as

well you are seeing something called as

photon in data bricks okay you are

seeing native executors in fabric those

are all built on C++ libraries using

Apache gluten and there was one thing more

um I forgot the name of the library the

one package is apache gluten and second

one I I I don't remember right now but

yeah those are just using your C++ as

the base okay that's like additional

knowledge but you should have that okay

so now you know like what's happening

behind the scenes now let's focus on the

code only because now you are well

versed with all the fundamental things

as Let's see. So I hope now you

understood like how we are just running

our Python file behind the scenes. Okay.

So this is different from C++ C

languages because again like those are

directly being compiled into machine

code and operating system can understand

the machine code right but in this case

you need an interpreter which is Python

virtual machine to understand your byte

code and then it will simply interpret

it line by line line by line and it will

simply uh give you the output that's the

only difference and let's now try to

master print statement first of all so

basically there are some things that you

can just do. So you will simply say hey

Anla can we also include let's say um

something other than string something

other than string. Yes you can just do

that. So basically let's say you want to say

say hello

hello

lamba. Okay. And now you just want to

include something else within the same

print statement. You can do that using a

comma. Okay. If I just do this, comma, I

can say hello lamba

lamba

one like this. Okay, I just want to do

that. Simply hit run and let's see what

happens. And if you just want to clear

your output, you can simply click on

clear and then simply run fresh. So you

will simply see hello an Lamba and then

one. Make sense? Make sense? Make sense?

So this way you can actually combine

multiple things and then if you again

want to add a string, you can simply do

that. Oops, not here. Here you can

simply do that. Let's say hello an

Lamba and then simply run it. See, you

can actually combine these things. Okay.

And you know what's the best thing? Let

me just look at the checklist that I

have made for you. The long chest check

checklist checklist. [Music]

[Music]

Okay. Let's cover this. This is very

very special and I I personally love

this. So

basically you will simply say hey anal

lamba what if we want to separate this

thing using a

delimeter example we know that we have

first string as hello and slamba then we

have second which is integer then we

have third. Is there any way that we can

actually add a kind of delimeter so that

we will know okay this is the first

value this is second this is third yes

you can actually do that so we have

something called as just add comma and

then say separated equals to and then

just type your delimter let's say I want

to add delimter called um dollar sign

okay now simply run this and you will

see hello anamba then dollar sign then

one then dollar sign then I love you or

eloop just write anything else. So this

is the way that you can actually create

a separator between your different

different entities that you are passing

within your print

statement. Now why did I write or why

did I use single quote here because I

wanted to make you think. So the thing

is whenever you are using print

statement you have liberty you have

liberty to use double quotes and single

quotes result will be the same. Let's

say this is in double quote. Let's say

this ILU is in the single code. It

doesn't make any difference. You can

simply run it and you will see. See

everything is same. So yes, you have

liberty to use double quotes and you can

say single quotes as well. Now one very

important thing you will say hey an

lamba can we do something like this? Um

let's say let me just create a new

statement. Let's say you are writing

I Hello Anala. This is

XYZ. How are you? Then you will say I

want to go to next line. Okay, I want to

go to next

line. So can we just do that like

something like this?

Um how is your

day? And should we just try run this

because Anela it makes sense right? See

um this is inside the double code so we

are not breaking any rule actually you

are. Let me simply run this. So it will

simply throw an error and you should

know the reason

why. You should know the reason bro. So

the reason is Python interprets the code

line by line. It will simply go to this

line. It will simply say hey what's

going on? you started the string and

where is the ending point? Then it will

go to next line. It will simply say hey

what you are doing man even like if it

will not even go to next line because

this will throw an error. But still let

me just tell you like how you can just

act like an interpreter. So it will

simply say hey in the next line what you

are doing you just started a string

without a double quote. So it will

simply throw an error. So it will simply

throwing an error called syntax error

un terminated string lit. That means

this string literal is not even

terminated here. So we got the error

here. But yeah, I'm just telling you

like what's going on. Okay. So now you

say okay. So you mean to say that in

Python we have to write all the

paragraph, all the text in one line.

Does that make any sense? No. So for

that we have the power of let's say this

is your code. If you want to just use

multi-lines to perform your you can say

anything which are constant right you

just need to write it and you cannot

write everything in the just in just one

line. So for that you simply need to use

three double quotes or three single

quotes. It's up to you. So let me first

use three single quotes. 1 2

3 1 2 3. That's it. Now you can just run

this. It will work. See it will work.

and it will simply give you how is your

day in the next line because it is in

the next line. Okay, you can even use

three double quotes 1 2 3

uh let me just remove it. 1 2 3 and

then 1 2 3 it will also work. It's up to

you. Okay, see I know we are just

covering from very basics but yeah it is

required. So now I hope that it makes

sense. Let's see what do we have next.

Um okay so

let's try to

cover hm now one important thing so let's

let's

say this is also important in the print

statement so let me just tell you that

as well so basically let's say you want

to write something like this hello anal

lamba can you do that let's say you want

to write something like this hello can

you do that

Yes. Yes, you can do that. But let's

remove this. If you are not using three

quotes, if you are let's say just using

single quote and you are just using

single quote here as well. Can you do

that? No. And you can see the error,

right? Because it doesn't know like

which is the main starting point and the

ending point because you are using the

same stuff here as well. But what if

this is your requirement? So we call it

as like escape character. There are like

many options to tackle escape

characters. You can even do like this.

Just add one more single

quote and one more single quote here as

well. Then it will be treated as escape

character. We will simply say hey just

escape this. Hey just escape this. That

means it is helping you helping you to

escape your characters. Okay. If I just

run this, it will simply give you

something like this. Hello an number.

Oh, it didn't put it like that. Yes. And

it should

not it should not. So the best way to

tackle it or you can say the simplest

way to tackle it I just perform this

step. Just change the double quote or

just change the single quote. If you're

using single quote here let's say you

want to uh do something like

this. So just use a starting and the

ending quote opposite of it. Double

quotes double quotes. Simple. This is

the simplest way. Okay, this is the

simplest way or it makes sense and it

promotes readability as well. What's the

other thing? You can even use backslash.

Okay, why do we use backslash?

Backslashes are used to tell Python

interpreter, hey, this is not a

character. Basically, this is not a kind

of literal that we are using. This is

just a constant that we want to use in

our string. So, what you can do, let's

say this is your double quote. Okay,

let's go back to the error view. So this

was the error. Now in order to mitigate

this thing, you can simply write

something like this. You can simply add

backslash like this. Add backslash like

this. Now if you just run this, it will

simply behave like this. So what it is

doing? It is escaping the character

backslash. It is escaping the character.

So it is saying hey I know that it is

using single quote here but you do not

need to treat it as like your normal

code. It is something that is related to

that user only. This is something a

constant. It is not your um defined

literal because in the programming

languages we have defined some meanings

to these characters like single quotes

for string double quotes for string like

this. So it is simply saying hey escape

escape escape this character. Make

sense? Why I'm just covering the string

in detail because in data engineering

domain we work with strings a lot. Let

me just give you a real time example

because whenever you let's say you are

using pispark if you do not know about

pispark pispark is like one of the

leading big data technologies that we

use. So in that we oftenly use like uh

paths storage path cloud urls and all.

So for that you need to make those URL

paths dynamic. you need to include uh

even functions in that. So for all those

purposes you have to use string you have

to just master strings and obviously we

are just trying to cover a lot of stuff

through print statement so that you can

actually see those things with your eyes

make sense. So this is not just your

print command. Do not say like why we

just covering print command in detail.

No, we are trying to learn most of the

stuff that are in the string not in just

print statement. Make sense? And there

are like a lot of stuff that we will

just covering uh in the very few next

minutes. Let's say fring. What are

frings? I love frings. If you are just

working with cloud urls, fstrings are

like the best thing that we have. And we

have indexing as well. So we will just

cover all these things. But now I know

that you have built a strong base in

string. you know how to work with like

double quotes, single quotes, multi-line

and all. Now you're good. Now you are

good. Okay. Now let's try to clear

everything and let's start with the

variables. Okay. Let's start with the

variables. Now let's talk about the

variables. Okay. Variables. Yes. Let's

talk about the variables. Basically what

are variables? Variables are like your

containers. Containers. Yes. a kind of

jar in which you can just save something

in you in which you can just put some

value and you can just store it let's

jar not

now okay so let's say this is a

container okay this can be a variable

okay this variable can hold your data or

can hold some value, can hold anything.

Let's say you are putting sugar inside

this. This will hold sugar. Let's say

you are just putting pulses inside this.

This will hold pulses. Let's say you are

just um putting salt. It will hold hold

salt. So that's why similarly your

variables are the same. Let's say I'm

just creating the variable. Variable

name is let's say my variable. Okay. So

I want to store my name inside this. I

will simply say an perfect now I can

access this name through this variable.

If I just simply write print my variable

I will simply see my name an I didn't

say print an but still I'm seeing this

value. Why? Because I have hold or you

can say I have stored this information

inside this variable which is my

variable. Make sense? This is very

simple concept. to not make it

complicated. This is just a variable.

Now you will say, hey, can I store

integer values in this? Can I store

numeric values? Yes, you can store

anything. Let's say I'm saying my where

or let's say uh x because it is very

popular term in mathematics like x

equals to this, y equals to this.

Similar to that one, let's say I'm

storing x= 10. I can simply say print

my and x together. And you know like how

we can just do this because of this

comma right let's say see an 10 simple

simple simple simple now let's say I'm

creating another variable

y I will simply say five if I want to

perform arithmetic operations on top of

these variables we can do that really

yes I will simply say

print x + y. Okay. Then I will simply

see 15. Oh, so it automatically

automatically

performed arithmetic operation which is

addition on x and y. Yes, you can do

that. Okay. What if I want to add the

strings? You will say, "Hey, Anchula, we

cannot add the strings." Um, by saying

adding the strings, I'm not saying like

add like real addition of strings. We

can even combine the strings using

variables. Let's say this is my variable

and I'm creating another variable called

last name and I was simply saying lamba.

If I just want to do this, I will simply say

say

variable plus last name. Let's see what

happens. You will see an lamba. So it

has just combined the strings because

obviously we cannot add an into lamba.

But yes, we can combine them. Make

sense? Very good. This is just like

addition of both the things. So what it

did, it simply put an then it simply put

lamba after this. That's it. Now, now,

now, now one very interesting thing. Can we

add 10 vidanch? Can we do this? Just

try. So if you just write this print x

plus my variable it will say bro have

some water. What you are trying to do? x is

integer. My variable is a string. What

do you want to achieve by combining

these? We cannot do that. We cannot do

that. If we want to do that you first

need to convert this x into string. Then

it is doable. Let's run this. Now you

can just do this because now it is a

string right and it is also string so it

needs like it knows like it will simply

combine both right very good now let's

see what do we have next so don't bother

I was just looking at my checklist so

because I want you to know everything

okay so we have discussed this this yeah

so now let's discuss multiple

assignments multiple assignments let's

say let's clear all this Let's say you

have values. Let's say x = 10.

Oops. x = 10, y = 5, then z equals or z

= to 20. You can just do this. But

there's a better way of doing it. Or you

can say if you just want to reduce a

line of codes, lines of code. So you can

simply say x ya z equ= 10a 5a 20. Really

just run this. Yes, it is successful.

Now what we did, we simply assigned

multiple variables together within

single line. It is called multiple

assignments. I hope that you are taking

notes. Okay, I hope you are taking notes

and if not just start taking notes right

now. Okay, because these are very basic

stuff that we are just going to wrap

really quick and then we going to just

cover like the advanced things and if

you are not taking notes you will not be

able to refer to the basic or

fundamentals. Okay, because we are just

wrapping it really quickly because these

are really basic stuff. These are like

really really basic. Okay. So this is

like multiple assignments and perfect

perfect and one more thing let's say if

you are all the variables have the same

values you can simply say x= y= z = 20

you can even do

this so all the variables will be having

the same value make sense make sense

make sense make sense very simple very

simple very simple so now we're going to

cover comments okay Why do we need

comment? Let me just write a code. Let's

say um let me just undo all the things.

Let's say I'm writing this code. Uh

yeah, let's say this is my code. This is

my code. Okay, it can be my code, right?

It is my code. So why do we need

comments? You will simply say an Ramba

comments are used to describe something

to just help us to review it later. This

is just like eight lines of code. What

do you want to describe it? We can

easily understand what is going on.

Okay bro, you are right. Just imagine

that you are writing thousands of lines

of code. What? Yeah, in real life you

write it bro. So can you understand the

part of let's say you have uh 1,000 rows

of code. Okay or you can say 1,000 lines

of code. Now within those 1,000 lines of

code, you are trying to understand the

line number 20. what that line is doing.

Trust me, you would spend the whole day

and I'm just I think talking like one

day is very less. Uh you would spend

maybe a whole month to figure out like

what is going on because it becomes so

so so complex to understand the code

when you're just reviewing it after a

month after 2 months after 3 months

after 1 year. That's where comments help

us to just tell us, hey, we did this in

this stage, we did this in this line, we

did this in this function, we did this,

we did that. So comments are really,

really handy for you as well and for

others as well. Let's say you wrote your

code and you are a superhum. You just

remember everything. Just imagine like

another developer is trying to read your

code. Everyone's um coding style is

different. Okay, how the person can

actually interpret the code? how the

person can understand like what is

written here. So for that we need

comments. So what I can do for comments

we have multiple option for comments.

Let's say I want to describe that this

is my name. Okay, this is my name. I

#myame. So this will be acted as a

comment. I know it is like really really

light color but yeah um you can even

change the colors but I don't want to

spend time on that one but you can just

actually see see my name. So whenever

now if anyone wants to understand this

code the person will say okay okay this

is his name this is maybe user's name or

anything. So this way you can add the

comments. Make sense? Very good. Now

this is one way of adding comments which

is very handy. Simply put hashtag and

write anything. But you cannot add

comments in the multi-lines. You cannot

extend your comments to the next line

because this will simply perform comment

on the same line only. Let's say you

want to write write at least three to

four lines of comments. So for that we

have another option. Let's say you want

to write comment here. So for that same

thing in uh string we use like three

single quotes or three double quotes.

Same thing. If you simply write here

like this 1 2 3 and then you simply say

comment I

uh I am

statement. So you can just write any number

number

of lines of you can comment then just

close it 1 2 3 that's it. The moment you

did this, this is your comment. You can

write anything between three single

quotes and three double quotes. The

choice is yours. Usually for comments,

we use three single quotes. Okay, so

this is the way to add multi-line

comments. Make sense? And whatever you

want to write it here, you can just

write it. Okay, this is like about your

comments and yeah, I I hope like this is

like pretty much clear. This is again

optional thing but this makes you a good

developer because this is really really

required if you are just trying to make

a user friendly code. Okay, makes sense. So

now let's talk about multi-line code.

Multi-line code. Yes. So let's say I

want to achieve something like this. Total

Total sum

sum

equals 10 + 20 + 30 + 20

+ 20 + 10 let's say so many numbers

right and the these numbers are like

taking all of my space okay now what I

can do obviously it will simply turn the

sum print total

sum okay it will simply print the sum

110 very good now you can even do this

thing. Let's say you just wrote your

code 10 + 20. Now you want to go to next

line. You will simply hit

enter. Okay. Then just move it to the

same you can say indentation. Now if you

just try to run this simply run this. It

will simply throw an error. It will

simply say hey what is this? Because

this is fine. This line is fine. But it

will when it will go to this line it

will simply say hey what is going on?

Then you need to tell that this line is

the part of this line. So for that we

use something called as backslash. The

moment you hit backslash this line will

be treated as the part of the previous

line. So backslash allows you to write

your code in multiple lines. Right?

Let's run this. Perfect. Now you are

seeing 110. This is again very handy

when you just write spark code or let's

say Python code for data engineering.

You just want to split your code in

multiple lines. So that's where it it

has become very useful. Another way of

achieving it that I have seen like other

developers use this way as well. You can

simply add a bracket in the at the start

and at the end of this this will also

work. If I hit run, this will also work

because this knows like this is the

beginning and this is the end of the

bracket and whatever inside this is the

part of the same stuff. Simple. It's up

to you. It's totally your choice what

approach you want to use. Right? Okay.

Very good. So this is also done. Now

let's talk about indentation. Now what

is this indentation? And I still

remember those days when my class

teacher used to scold me a lot. An Lamba

what you are doing? Why don't you indent

your code? I was like why I need to

indent my code? Because I back in the

school days u we had a computer lab and

um I was really new to those computers

and all. So C++ doesn't require indentation.

indentation.

No, because it is just like compile

directly. So we can just write our code

within one line. It will just behave

like normal. But in Python we cannot do

that. So I said like why do we need to

indent our program? My teacher used to

say like C. I know it is not important

for C++ but it promotes readability.

Second thing indentation is crucial part

in other languages as well and now I can

feel that. So basically what is

indentation? So I will just write a a

code that you will not or maybe you may

not understand but you will understand

it later just for the understanding I'm

just explaining you the indentation. So

I'm writing a code let's say like this

if x

= 1 then just print

print wow

wow

okay and x equals 1. So if I just run

this, it will work fine. It will say

wow. So what is indentation? So

indentation means I have started this

condition. If condition, don't worry

about that. We will talk about if just

after this. Okay. So it will simply say

if I have started this, you can say

condition. And this is my syntax for if

condition. Then I know that everything

I'll be writing under this will be part

of if condition. Right? This is not a

separate print condition. Make sense? I

know it doesn't make sense for now if

you do not know about if condition but

try to make some sense because once I

will discuss about if it will be very

much clear but try to just grasp the

context of indentation. So basically if

you just do this you will simply say hey

if x= to= to 1 print wow it should work

right really no because it is saying if

x= 1 then what I need to

do okay I'll simply say print wow okay

and then if I just put here wow it will

work it will work see wow wow because

this small wow is the part of this

particular if condition. That means if I

am just writing print right from the

start of the line, it will not behave

like it is a part of if condition. That

is called indentation. You need to

indent your code. You need to just

follow the hierarchy. That means this is the

the

parent. This is its child. That's it.

You need to follow the hierarchy. You

need to have some space before the child

before the child code. Okay, this is the

kind of hierarchy that you need to

follow. Make sense? Very good. This is

all about indentation. So do not worry

about if condition. We will just talk

about if condition as well. It is very

simple. And if you already know Excel,

this should be a piece of cake for you.

But still, I'm just explaining these

stuff because this is really important

from the fundamentals perspective. So

yeah I have to

now now let's talk about type casting it

is really important type casting. So

basically what is typ casting? This is

very fancy term but the meaning is so

simple. Let's say you have a equals to

10. Okay.

And b equals

um 10. Make sense? One is integer. The

second one is string.

If we try

to add these

numbers, can we achieve this? Obviously

no. We have already seen the error. Let

me just show you again. Print a + b. We

will see the error, right? Error.

Perfect. But we can convert this number

into a different type. That means we can

perform type casting something like

this. We can perform

string to integer. Make sense?

We can perform like this string to

integer. Wow. Can we do that? Yes. This

is called type casting. When you are

just converting one data type to

another, that's it. This is type

casting. So how we can just do that? We

have a function called cast. Okay. I

will simply

say first of all let me just show you

how you can see the type. If you are not

sure like what type is this? I know it

is very much evident but sometimes it's

not. So in order to see the type, you

can simply say print type of B. it will say

say

string see class string so it is a

string data type now if you want to just

type cast it okay so how we can just do

that I will simply say b new so I will

simply create a new variable and I'll simply

simply

say cast or you don't need to write cast

so you will simply say integer of

b okay now let's try to see the type of

b new let's

Oops. We need to write

type. Okay. Now let's try to do this.

Now it has converted into

integer. Wow. So whatever you want to

convert, let's say you want to convert

it into integer. You can simply write

this. What if you want to convert this

into string? Maybe you want to just

convert into string. Simple steps are

very simple. Let's say a new. Okay. Let

me just go to the next line. I will

simply say a new

new

equals string of a and let's see the

data type of a. This time you will

simply see string. Wow, perfect. This is

so simple. This is called

explicit type

casting because you are explicitly

telling Python, hey just change this

data type to this. Hey just change this

data type to this. So this is explicit

type casting. We do have something

called as implicit type casting as well.

Like what now? What's this? In implicit

type casting we do not tell that hey

just change this number. It becomes

understood to change that. Really the

very good example is this one. Let's say

you have a equals to 10 b= to

10.5. So now this is a different data

type right? This is integer. This is

float. This is float, right? This is

float. I can even show you print type of

B. Okay, makes sense. Float. Now, if you

just try to perform a plus b, you can

really how? Because this is integer,

this is float. But we know that we

cannot perform at like any arithmetic

operation if both are of different um

data types. But if Python can do that it

will basically both are numeric data

types. One is numeric means like in

numbers. Okay. 10 and 10.5. So it knows

that it makes sense that it will simply

convert this a= to 10 equals to

10.0 10.0. And this will do it

implicitly. That's why it is called

implicit type casting. So it will simply

add 10.0 0 to 10.5. Okay, make sense?

Very good. Very good. Very good. So

every time you do not need to just

perform type

casting. Now let me just tell you that

the string the string actually behaves

as an array. Now what is an array? Array

for the simplicity for now you can

just try to understand if you just want

to understand array. array is like group

of values or if you're familiar with

list, list is actually a defined type

but if you because list is very common

and that can be used in let's say other

things as well not just in programming

languages. So basically if I'm just

writing something like this let's say um

variable or let's say x

equals lamba okay so

actually we can say that it is equivalent

equivalent to

to a

a n

n s

h. So each character each character is different.

different.

Oops. Each character is different. So

that's why we can actually treat this

text as an array. Really? Yes. So let's

say you just want to print the first

character of this particular string only

the first character. And we already know

that in the programming languages we

start the counting from zero not from

one. And if you don't know now you know.

So we always start the counting from

zero. So let's say I want to print the

first character. So what will be the

first character? I will simply say x.

And in order to define the index, we use

these square boxes or you can say

braces. And then I will simply say zero.

If I just run this, I should see a

perfect. Let's say I want to get the

next alphabet. I will simply say one. I

will simply get n. So that means I I can

simply perform indexing on top of this

string because this acts as an array.

This acts this behaves exactly same as

an array. The string makes sense. Now

obviously we'll be just learning a lot

about slicing in the lists but you

should have a strong grasp over you can

say slicing concepts and all. So now let's

let's

say I want to fetch the first four

characters. First four characters I want

to fetch a and sh how you can do it

because obviously we know that we can do

something like this x of0 okay we'll get

a then we'll get n

but what if you want to just fetch first

four characters together so it is called

slicing. So how you can just perform

slicing? We have something called as

let's say zero. Okay. Then you will

simply say colon and then whatever your

end number is. My end number is four. So

I'll simply say four. Now you will see

my name an make sense. So how it is

going through each alphabet? It is first

going to a which is zero then n which is

1 then s which is three uh sorry two

then h which is three. So where is four?

So the thing is this four is not

included not included. So every time it

will go till n minus one. So if you if

your uh last number is four then it will

simply perform n minus one and it will

simply give you three.

Make sense? That's how it works for your

strings. I hope it makes sense. Okay.

So, this is your slicing. Let's say you

want to just pick like specific numbers.

Let's say you want to pick only

um numbers from h till m. So, you can

just count the index. You can simply say

0 1. So, a is 0. Okay. So, this is zero.

Let me just expand the screen. Okay.

Perfect. So this is zero. This is one.

This is two. This is three. This is four.

four.

5 6 7

8. Make sense? 0 1 2 3 4 5 6 7 8. If you

just want to fetch H L A M. So what

should be the index? Index should be

three as the starting point

and 3 4 5 6 6 from 3 till 6 but now you

know that we simply go till n minus one

that means you will simply give seven so

that it can include the sixth index so

we'll simply write something like this

three and then six sorry seven you can

simply run it this time you will simply

say c hm

Perfect. Perfect. We even have something

called like this. And this is really

interesting. If I do not specify

anything, what will happen? What will

happen if I do not specify anything? And

I simply specify a colon. That's it. You

will see the whole text. Why? Because we

have a concept here. Let me just tell

you what's that. So if you do not put

any value in the starting point, it will

automatically take zero.

If you do not put anything in the end

point, it will automatically take n as

the end point. Now what is n? This can

be a good question. What is n? n is your

length length of your

string. In our case, what is the length?

Length is 9. So it will simply say x

0 colon 9. This will be your past you

can say

arguments and it will automatically feed

that. Let me just show you. If I simply

write zero and if I simply say len of x,

you will simply see the same thing.

Anchel lamba. Now what is this len? Len

is a function that we use with the

arrays to find the length of it. That

means how many elements do we have

within that list or within that array.

And as we just mentioned, strings behave

similar to

arrays. That's it. That's it. Now one

interesting thing. Let's say you do not

put anything here. Just a quick quick

check for you. What will happen? We will

simply see everything. Why? Because it

will simply put zero here

automatically. Okay, very good. Simply

put zero here automatically. This way

you can just slice your text. Whatever

you want to get, whatever you want to

just fetch from the long text, you can

just do this. Make sense? We will just

learn about a lot in around like slicing

in the list chapter. So, do not worry.

Let's see what do we have next? Next, next.

next.

So, okay. So, let's discuss some of the

you can say string methods that we use

on a daily basis. Uh there are so many

string methods. You can even Google and

methods in Python. There are so

many you can simply click on this and

you will see capitalize case fold center

count and code like so many see there's

a long list and as per your convenience

you can just use these functions but

simply just to make you aware how they

work I will simply show some of the examples

examples

but this will be really helpful when you

actually working with Python in the data

engineering projects because this is

something that you cannot Remember this

is something that okay I need to perform

this let's see what function do I have

in Python tuck tuck tuck tuck tuck you

will simply go on Google then you will

see oh I have this function for this

then you will use that because you

cannot remember all the functions so do

not worry you do not need to remember

anything if you want to use let's say

count function if you just want to use

let's say length function you will

simply go on Google hey tuck tuck length

function in strings in Python you simply

need to know the concept that's it

that's That's it. Then you will simply

grab the particular function because it

is not possible to remember all the

functions. You need to remember like yes

we do have a function like this. Yes, we

can just do uh this thing in Python with

this approach. You need to know all

those things but you not need to

remember like all the functions.

Exactly. Because you would be working

with so many languages. Every language

has a different naming convention for

the functions. How you can just remember

all those things? Impossible, right?

Impossible. And we are in the AI era.

You need to just learn things smartly

because what those things are like

easily available in just one click. So

you need to focus on the complex things

now. You do not need to just waste your

time in just getting hey how I can just

use upper hey how I can just use lower.

No. Okay. So let me show you some of the

things. So how you can just do uh where

should I just keep my notebook? Okay.

Here it is fine. So let's cover very

basic stuff which is upper and lower.

Okay. So let's say my name is

number make sense if I just want to

capitalize all the things I will simply

say print X dot

upper. Okay. And it will simply say

anlamine capital. Same with lower. If I

just want to make make it lower, I will

simply say lower. That's it. Simple

simple simple simple in you can say

Excel we have something called as proper as

well. So we do not have proper here. So

if you just want to find proper see so

now how I will just approach I know that

we should have a proper function in uh

Python right? So you can simply go on

Google you'll simply say proper string

Python and you can even open this one

but yes you have something called Python

string methods as well. So here you can

simply try to find something called as

like related to string. So these are all

the methods and you can just have a

quick look like what are the functions

available and what I can use here. So

you can simply say format format

specific value in a string. So you can

actually see like what do we have? See

capitalize capitalize like converts a

first character to uppercase. So I think

it should work here. Capitalize. So I

can simply use this capitalize and copy and paste. So you can simply

and copy and paste. So you can simply say x dot

capitalize. Okay. So it will simply make my first alphabet equals to capital. So

my first alphabet equals to capital. So that's how you need to fetch the

that's how you need to fetch the functions accordingly because if you're

functions accordingly because if you're using any other language, you will have

using any other language, you will have another function name. But you know that

another function name. But you know that the purpose is there. We would have some

the purpose is there. We would have some functions available in Python. So that's

functions available in Python. So that's how you need to learn with the

how you need to learn with the requirements. And yes, the more

requirements. And yes, the more functions you would be using, the more

functions you would be using, the more familiar you will be with those

familiar you will be with those functions. We like rarely use these

functions. We like rarely use these functions like upper lower and we use

functions like upper lower and we use upper and lower a lot but not

upper and lower a lot but not capitalized alone because we are not

capitalized alone because we are not designing a website. We are just simply

designing a website. We are just simply using those function the joining key. So

using those function the joining key. So we use upper lower a lot. Okay. So next

we use upper lower a lot. Okay. So next we have a very good example. It's called

we have a very good example. It's called replace. So let's say I want to replace

replace. So let's say I want to replace something within this text. How I can

something within this text. How I can just do that? So I'll simply say I will

just do that? So I'll simply say I will make use of replace function. What it

make use of replace function. What it will do? As the name suggest it will

will do? As the name suggest it will simply replace something. Let's say I

simply replace something. Let's say I want to replace print x

want to replace print x dotreplace and I want to replace h with

dotreplace and I want to replace h with let's say z. Okay, let's see what we

let's say z. Okay, let's see what we will get. I will get uns

will get. I will get uns lamba. So actually you can perform

lamba. So actually you can perform replace function like this if you just

replace function like this if you just want to replace anything within the

want to replace anything within the string. How it is possible? Because it

string. How it is possible? Because it acts and it behaves like an array. What

acts and it behaves like an array. What if I want to replace two things? Let's

if I want to replace two things? Let's say I want to replace sh with Z. Can we

say I want to replace sh with Z. Can we do that? Yes. And

do that? Yes. And lamba. So we can do that. It is

lamba. So we can do that. It is possible. Okay. Now what do we have?

possible. Okay. Now what do we have? Yeah, this is really important. This is

Yeah, this is really important. This is really important because this is

really important because this is something related to list and for data

something related to list and for data engineers list is very important. So

engineers list is very important. So basically let's say you have this an

basically let's say you have this an Lamba and let's say um this is my

Lamba and let's say um this is my nickname at home. um let's say these

nickname at home. um let's say these three things. Okay. So

three things. Okay. So basically what if I want to split all

basically what if I want to split all the things within the string based on a

the things within the string based on a delimeter let me repeat let's say this

delimeter let me repeat let's say this is one entity an this is second entity

is one entity an this is second entity this is third entity and I know this I

this is third entity and I know this I want to separate this and I want to

want to separate this and I want to store it how I can do that there's a

store it how I can do that there's a function called split so what split

function called split so what split function does split function will

function does split function will automatically split your string based on

automatically split your string based on the character that we will define and it

the character that we will define and it will simply store all the items within a

will simply store all the items within a list within a list. Let me just show

list within a list. Let me just show you. I will simply say uh my list equals

you. I will simply say uh my list equals I will simply say x do.split and now on

I will simply say x do.split and now on which telemter you want to split the

which telemter you want to split the values. Here we have a special

values. Here we have a special character. No, we cannot see it. You can

character. No, we cannot see it. You can see it. Space is

see it. Space is also a delimeter in Python. Okay. So,

also a delimeter in Python. Okay. So, we'll simply say space. That's it. And

we'll simply say space. That's it. And let me just print the list. Don't worry,

let me just print the list. Don't worry, we're going to cover list next. But you

we're going to cover list next. But you should have some basic understanding

should have some basic understanding like about list. List is just like

like about list. List is just like holding your all the items. Okay. So,

holding your all the items. Okay. So, let me just run. See this is a list.

let me just run. See this is a list. list is having all the things like my

list is having all the things like my name, first entity, second entity, third

name, first entity, second entity, third entity. This is a list. So this way you

entity. This is a list. So this way you can actually convert your string into a

can actually convert your string into a list based on a delimter. And here space

list based on a delimter. And here space is the

is the delimer. So we have like a lot of

delimer. So we have like a lot of functions as well like other than these

functions as well like other than these and string we have let's say r strip.

and string we have let's say r strip. Let's oh yeah ends with first first I

Let's oh yeah ends with first first I will just cover ends with and starts

will just cover ends with and starts with it is very important for data

with it is very important for data engineers. So let's say you have because

engineers. So let's say you have because we use these things when we are just

we use these things when we are just trying to read some data from the files.

trying to read some data from the files. Let's say you have a file like this um

Let's say you have a file like this um raw

raw data dot CSV. Yeah, let's try to just

data dot CSV. Yeah, let's try to just use our own analogies because we are

use our own analogies because we are just covering it for data engineering.

just covering it for data engineering. Let's say you have something like this.

Let's say you have something like this. Let's say file name file equals raw data

Let's say file name file equals raw data dot csv. But you need to only read this

dot csv. But you need to only read this file if this is a CSV file. What you

file if this is a CSV file. What you will do in this scenario? you will use a

will do in this scenario? you will use a function called ends with or starts

function called ends with or starts with. It's up to you whatever you want

with. It's up to you whatever you want to use. So how we can just use this? I

to use. So how we can just use this? I will simply say

will simply say um print or I will simply use if

um print or I will simply use if condition basically because again I will

condition basically because again I will just explain if condition as well. But

just explain if condition as well. But if condition is simply like checking

if condition is simply like checking like what is going on and what's the

like what is going on and what's the condition. It will simply return true or

condition. It will simply return true or false. I'll simply say if

false. I'll simply say if um file dot ends with ends with the

um file dot ends with ends with the function ends with ends with what dot

function ends with ends with what dot CSV. If it is ending with dot CSV then

CSV. If it is ending with dot CSV then print CSV file. Okay, make sense. Let me

print CSV file. Okay, make sense. Let me just run this. Perfect. Yes, this file

just run this. Perfect. Yes, this file is ending with dot CSV. That is why we

is ending with dot CSV. That is why we are getting dot CSV.

are getting dot CSV. This is the thing that we use in data

This is the thing that we use in data engineering. While reading data on a

engineering. While reading data on a daily basis, you can just apply check

daily basis, you can just apply check marks. You do not need to just read all

marks. You do not need to just read all the data. You can just simply read

the data. You can just simply read selective data. Make sense? Very good.

selective data. Make sense? Very good. So now let's say this data is dot

So now let's say this data is dot [Music]

[Music] um let's say what I will get nothing

um let's say what I will get nothing because this is not a CSV file. So

because this is not a CSV file. So that's how you use dot ends with method

that's how you use dot ends with method with

with your

your strings. Same thing you can just do with

strings. Same thing you can just do with starts with as well. Same you can simply

starts with as well. Same you can simply say

start. Okay. And I will simply say if it is starting with raw then simply say raw

is starting with raw then simply say raw data raw file. Let's see. Yeah perfect

data raw file. Let's see. Yeah perfect because it is starting with raw. So it

because it is starting with raw. So it will simply check the starting alphabets

will simply check the starting alphabets and from here like in the previous

and from here like in the previous example in dot CSV it checked the last

example in dot CSV it checked the last alphabets. Okay, very good. I hope it

alphabets. Okay, very good. I hope it makes sense. It makes sense. Now what do

makes sense. It makes sense. Now what do we

we have? Oh, okay. Let's do this

have? Oh, okay. Let's do this now. Let's say you have a statement.

now. Let's say you have a statement. Okay, let's say you have a statement.

Okay, let's say you have a statement. UI statement something like this.

doing? [Music]

Hey, I'm talking to you. Okay, now this is very interesting. Why? Because you

is very interesting. Why? Because you can ask me hey an you didn't even define

can ask me hey an you didn't even define like three quotes or three single quotes

like three quotes or three single quotes why it is like still a string because I

why it is like still a string because I didn't hit enter I was just writing and

didn't hit enter I was just writing and due to the insufficient space it moved

due to the insufficient space it moved to next line. So ideally it is just a

to next line. So ideally it is just a single line for Python right just to

single line for Python right just to make you aware it moved to next line

make you aware it moved to next line because of the space. Okay. So now in

because of the space. Okay. So now in this statement if I just want to check

this statement if I just want to check like how many times unword is appearing

like how many times unword is appearing can we do that? Yes, we have something

can we do that? Yes, we have something called as count function. I will simply

called as count function. I will simply say

say print

print statement dot count and what are we

statement dot count and what are we counting? Let's say un. Okay, simply run

counting? Let's say un. Okay, simply run this and I will get two because I'm just

this and I will get two because I'm just seeing my name two times. That's how you

seeing my name two times. That's how you can just find these words. If you are

can just find these words. If you are just let's say building a model or if

just let's say building a model or if you just want to make sure like how many

you just want to make sure like how many times we are using that word, you can

times we are using that word, you can simply perform word counts like this.

simply perform word counts like this. Okay. Okay. Let so we have like so many

Okay. Okay. Let so we have like so many functions available in string. Again we

functions available in string. Again we are covering this video for the data

are covering this video for the data engineering perspective. So you can just

engineering perspective. So you can just refer the function whatever you want to

refer the function whatever you want to use. Obviously we cannot just look for

use. Obviously we cannot just look for all the functions in string. These are

all the functions in string. These are the major functions that we use with

the major functions that we use with data engineering. And that's the agenda

data engineering. And that's the agenda of this video because we'll be cover we

of this video because we'll be cover we will be covering those things which are

will be covering those things which are directly aligned with data engineering.

directly aligned with data engineering. Python is a vast or you can say widely

Python is a vast or you can say widely used language. Okay, why am I again

used language. Okay, why am I again repeating this? Because you will feel

repeating this? Because you will feel like hey we have this thing as well. I

like hey we have this thing as well. I know I know we have a lot of stuff in

know I know we have a lot of stuff in Python. We have a lot. So now let's say

Python. We have a lot. So now let's say we going to

we going to cover. Yeah, this is important. This is

cover. Yeah, this is important. This is important. So let's

important. So let's say you have a string like last thing

say you have a string like last thing that we are just covering a string

that we are just covering a string because this is also important. Okay,

because this is also important. Okay, then we're going to jump on if

then we're going to jump on if statement. I know you are waiting since

statement. I know you are waiting since so long. So in this thing let's say you

so long. So in this thing let's say you have a variable okay or let's say demo

have a variable okay or let's say demo demo string okay you have demo string

demo string okay you have demo string like

like um or even not even string let's say

um or even not even string let's say because this is like irrespective of

because this is like irrespective of string this is a function that we use

string this is a function that we use okay this is also called is functions

okay this is also called is functions this is called is

this is called is functions okay so let's

functions okay so let's say you need to just define a demo

say you need to just define a demo string like this. Hello. Simple. Then

string like this. Hello. Simple. Then you can say demo

you can say demo variable. Okay, obviously this is also

variable. Okay, obviously this is also variable. This is also a variable. This

variable. This is also a variable. This is just a name. And this has a value

is just a name. And this has a value let's say 10. Okay. If I say

let's say 10. Okay. If I say print demo

print demo string dot is number, what it will

string dot is number, what it will return? What? Error. The is numeric.

return? What? Error. The is numeric. Sorry, not is number is

Sorry, not is number is numeric. See, every language has

numeric. See, every language has different

different functions. False. False. Oh yeah, by the

functions. False. False. Oh yeah, by the way, so this is another reason why do we

way, so this is another reason why do we use code editors? Because in the code

use code editors? Because in the code editors, we get some suggestions

editors, we get some suggestions whenever we are just writing something.

whenever we are just writing something. So it is not giving me suggestion

So it is not giving me suggestion because we have not installed pylance.

because we have not installed pylance. Pyance is just like an extension that we

Pyance is just like an extension that we use with VS code editor. But I would

use with VS code editor. But I would recommend you to use those core editors.

recommend you to use those core editors. It is really good. So yeah we were just

It is really good. So yeah we were just talking about is function. So it is

talking about is function. So it is simply saying is it numeric? No. Why?

simply saying is it numeric? No. Why? Because is it string?

Because is it string? Yes. So that's how we check like if a

Yes. So that's how we check like if a particular variable is numeric is alpha

particular variable is numeric is alpha numeric is string is something like

numeric is string is something like that. So we have so many is functions.

that. So we have so many is functions. If I write demo variable let's say like

If I write demo variable let's say like this. Will it return true? No. Why? So

this. Will it return true? No. Why? So here you have to use as functions with

here you have to use as functions with with only and only strings. So if I just

with only and only strings. So if I just encapsulate in double quotes that means

encapsulate in double quotes that means it becomes string right? If you just run

it becomes string right? If you just run this it will say true. Wow this is

this it will say true. Wow this is really helpful. If you just observed

really helpful. If you just observed what it did, I know this is string but

what it did, I know this is string but still we can confirm that within this

still we can confirm that within this string do we only have numbers or

string do we only have numbers or string. Wow, this is amazing. This is

string. Wow, this is amazing. This is amazing because we are getting

amazing because we are getting everything that we need if we just want

everything that we need if we just want to inspect like what is inside that

to inspect like what is inside that string. Is it a number? Is it let's say

string. Is it a number? Is it let's say a string? Okay. And we have something

a string? Okay. And we have something called as is alnum as well. What is

called as is alnum as well. What is al-nam? So al-nam means like alpha

al-nam? So al-nam means like alpha numeric. Let's say I I write 10 a bc. If

numeric. Let's say I I write 10 a bc. If I just run this, it will simply return

I just run this, it will simply return false. But if I just write is

false. But if I just write is alnum, it should work and it will say

alnum, it should work and it will say true because it has numbers and text

true because it has numbers and text both. So let's say you are reading one

both. So let's say you are reading one file and you know that in your file you

file and you know that in your file you should see text and number both. You can

should see text and number both. You can apply this condition and you can simply

apply this condition and you can simply say if it is alum only read that file

say if it is alum only read that file otherwise do not read that. So you can

otherwise do not read that. So you can just perform these things. See how

just perform these things. See how powerful it becomes when you just

powerful it becomes when you just combine these things with data

combine these things with data engineering. Make sense? Very good.

engineering. Make sense? Very good. These are very very like very simple.

These are very very like very simple. Very

Very simple. It's just like more you work

simple. It's just like more you work with these things better you understand

with these things better you understand that thing. Okay. So now let's finally

that thing. Okay. So now let's finally cover if else statement or you can say

cover if else statement or you can say conditionals in Python. So if else

conditionals in Python. So if else statement is so popular it's even in

statement is so popular it's even in Excel. Okay. And because of that people

Excel. Okay. And because of that people make a fun of Excel that Excel is also a

make a fun of Excel that Excel is also a programming language just because of

programming language just because of that if else statement. So basically

that if else statement. So basically what is if else statement? It is pure

what is if else statement? It is pure English. If this is true do

English. If this is true do that if not do that do other thing.

that if not do that do other thing. That's it. Same thing it is here as

That's it. Same thing it is here as well. So let's say I define a variable

well. So let's say I define a variable called x= 10. Okay. If I say if now it's

called x= 10. Okay. If I say if now it's up to me if I want to encapsulate my

up to me if I want to encapsulate my condition in uh braces. Ideally I would

condition in uh braces. Ideally I would recommend you always encapsulate the

recommend you always encapsulate the condition in braces. It promotes

condition in braces. It promotes readability and sometimes it eliminates

readability and sometimes it eliminates the errors as well. Okay. Very good.

the errors as well. Okay. Very good. These small things make you a better

These small things make you a better developer. So if x equals to equals to

developer. So if x equals to equals to 10. Now what is this equals to equals

10. Now what is this equals to equals to? We cannot say if x equals to 10.

to? We cannot say if x equals to 10. Why? Because if we say x equals to 10,

Why? Because if we say x equals to 10, we use single equals to to assign the

we use single equals to to assign the number to that variable. But to check

number to that variable. But to check the condition, we use double equals to.

the condition, we use double equals to. Okay, this is a simple thing but you

Okay, this is a simple thing but you should be aware of. If x equals to

should be aware of. If x equals to equals to 10 then you need to once you

equals to 10 then you need to once you just return your condition. Okay. Then

just return your condition. Okay. Then you can simply say colon and hit enter.

you can simply say colon and hit enter. By default you will not land in the

By default you will not land in the first you can say character line like

first you can say character line like this. You will not land here. You will

this. You will not land here. You will automatically land here. Why?

automatically land here. Why? Because this compiler promotes this com

Because this compiler promotes this com compiler promotes indentation and most

compiler promotes indentation and most of the compilers promote that as well.

of the compilers promote that as well. So you do not need to every time hit tab

So you do not need to every time hit tab and then go to that particular area. No,

and then go to that particular area. No, you can simply hit enter and you will

you can simply hit enter and you will land on the right place. So now you can

land on the right place. So now you can just print anything or you can do

just print anything or you can do anything. Anything means anything. You

anything. Anything means anything. You can simply say

can simply say print. Okay, you can simply say print

print. Okay, you can simply say print um x is 10. Simple. If I run this, you

um x is 10. Simple. If I run this, you will see that. Oh, okay. So now in if

will see that. Oh, okay. So now in if else condition, we can either use if as

else condition, we can either use if as an independent operation or we can

an independent operation or we can combine it with else as well. That's

combine it with else as well. That's what we do most of the time. If x equals

what we do most of the time. If x equals to equals to 10 that means print x is

to equals to 10 that means print x is 10. Now we need to take exit from this

10. Now we need to take exit from this if. Now we need to use else as an

if. Now we need to use else as an independent command. We'll hit

independent command. We'll hit backspace. I'll simply say else. That

backspace. I'll simply say else. That means if x is 10, print x is 10. If x is

means if x is 10, print x is 10. If x is not 10, then what? We will simply

not 10, then what? We will simply print. We will simply print x is not

print. We will simply print x is not 10. Make sense? Okay. And see

10. Make sense? Okay. And see indentation here as well. We get x is

indentation here as well. We get x is 10. If I say x= to 11, I will simply say

10. If I say x= to 11, I will simply say x is not 10. So that means it will first

x is not 10. So that means it will first go here. If this condition is not met,

go here. If this condition is not met, it will simply go here on this line.

it will simply go here on this line. Make sense? Now what if we want to add

Make sense? Now what if we want to add something like third statement? If x=

something like third statement? If x= to= to 10, make sense. If not makes

to= to 10, make sense. If not makes sense. What if I want to do something

sense. What if I want to do something between those? If x= to= to 10, then x

between those? If x= to= to 10, then x is 10. If x may be greater than 100, I

is 10. If x may be greater than 100, I will say x is too big. and then I will

will say x is too big. and then I will say x is not 10. So for that we simply

say x is not 10. So for that we simply use something called as l if. l if means

use something called as l if. l if means else if together. Okay that means if

else if together. Okay that means if then else if then else. Else will be

then else if then else. Else will be treated as the end of the condition.

treated as the end of the condition. When neither of the conditions were

When neither of the conditions were succeeded were like met then it will

succeeded were like met then it will simply go to else but before that will

simply go to else but before that will simply go to lf. Okay. I will simply say

simply go to lf. Okay. I will simply say lf x greater than 100. It will simply

lf x greater than 100. It will simply say

x is too big. Make sense? Let's say I assign x= to 110. It will simply say x

assign x= to 110. It will simply say x is too big. So it will simply go

is too big. So it will simply go to this command first. It didn't pass.

to this command first. It didn't pass. It will go to second. It passed. Wow. It

It will go to second. It passed. Wow. It returned this. If I say x equals to 11

returned this. If I say x equals to 11 for one more time, it will simply say x

for one more time, it will simply say x is not 10. That means it went here, it

is not 10. That means it went here, it failed, it went here, it failed, it went

failed, it went here, it failed, it went here. Obviously, it will always be

here. Obviously, it will always be passed because this is the last

passed because this is the last statement. It has to return something

statement. It has to return something like this. Okay, make sense? This is

like this. Okay, make sense? This is like else if statement. Now you can

like else if statement. Now you can perform inherited else if statement as

perform inherited else if statement as well. That's what we do in data

well. That's what we do in data engineering as well. So let's say let's

engineering as well. So let's say let's say if our x = to= to 10, we want to

say if our x = to= to 10, we want to continue this as a separate branch. Let

continue this as a separate branch. Let me just explain. If x= to= to 10. Okay,

me just explain. If x= to= to 10. Okay, if x= to= to 10, I will simply say

if x= to= to 10, I will simply say another if condition within this. This

another if condition within this. This is called nested if. I will simply say

is called nested if. I will simply say if x or you can say if x equ= to 10 or

if x or you can say if x equ= to 10 or let's

let's say let's perform nested if inside this

say let's perform nested if inside this because we we can just generate so many

because we we can just generate so many uh you can say conditions within this

uh you can say conditions within this let's say if I want to do

let's say if I want to do if x because we just know that x is

if x because we just know that x is greater than 100 it can be 1,000 it can

greater than 100 it can be 1,000 it can be 10,000 it can be one lakh it can be

be 10,000 it can be one lakh it can be 10 lakh so it can be like any big

10 lakh so it can be like any big number, right? So, we will simply define

number, right? So, we will simply define the level of x. We will simply say if

the level of x. We will simply say if x greater than

x greater than uh or let's say yeah greater

uh or let's say yeah greater than

than 200 make sense. If x is greater than 100

200 make sense. If x is greater than 100 or let's say 100 because it will simply

or let's say 100 because it will simply continue with that statement. If x is

continue with that statement. If x is greater than 100

greater than 100 and and x is less than 200 then you need

and and x is less than 200 then you need to

to print

print between 100 and

between 100 and 200. That's it. You can run this. So

200. That's it. You can run this. So I'll simply say 110. What it will do?

I'll simply say 110. What it will do? Let me just show you. So we will

Let me just show you. So we will understand it using the flow. It will

understand it using the flow. It will simply go here. First of all it failed.

simply go here. First of all it failed. So it is rejected. It went here. LF, it

So it is rejected. It went here. LF, it passed. So it is now entered within the

passed. So it is now entered within the L if command. Yes, here. Then within

L if command. Yes, here. Then within this, it just went through the if

this, it just went through the if condition. It is saying if X greater

condition. It is saying if X greater than 100 and less than 200 simply print

than 100 and less than 200 simply print between 100 and 200. You can even

between 100 and 200. You can even continue with this else statement as

continue with this else statement as well. Let's say

well. Let's say else

else print greater than

200. Make sense? Let's say I say 210. It will simply say greater than uh

210. It will simply say greater than uh wait

wait what? And x less than

what? And x less than 200. Oh, I see. So that's why I always

200. Oh, I see. So that's why I always say that add braces as much as you can.

say that add braces as much as you can. And this is the best example to

And this is the best example to demonstrate my point and I'm happy that

demonstrate my point and I'm happy that I saw this error. So basically it is

I saw this error. So basically it is creating a conflict a kind of conflict

creating a conflict a kind of conflict because it is not actually treating it

because it is not actually treating it as like two different

as like two different conditions. So in order to mitigate the

conditions. So in order to mitigate the risks you simply need to encapsulate

risks you simply need to encapsulate this as a separate and this as a

this as a separate and this as a separate condition. That's the power of

separate condition. That's the power of braces. And that's why whenever you're

braces. And that's why whenever you're doing any programming language your

doing any programming language your instructor or let's say your teacher if

instructor or let's say your teacher if you are in university or anything they

you are in university or anything they will simply ask you to just add braces

will simply ask you to just add braces wherever you can so that it will make it

wherever you can so that it will make it simpler for your compiler or interpreter

simpler for your compiler or interpreter to understand what you are actually

to understand what you are actually trying to do. If I just try to run this

trying to do. If I just try to run this again I should see greater than 200.

again I should see greater than 200. Perfect. So now what it is doing let me

Perfect. So now what it is doing let me just explain it one more time. It is

just explain it one more time. It is going here. It is not fulfilling the

going here. It is not fulfilling the condition. Failed. It went here. It

condition. Failed. It went here. It fulfilled. Then it actually entered

fulfilled. Then it actually entered within this LF. It simply performed X

within this LF. It simply performed X greater than 100. Yes. Is less than 200.

greater than 100. Yes. Is less than 200. Is it condition true? No. So it failed.

Is it condition true? No. So it failed. Then it went to else. Is it true?

Then it went to else. Is it true? Obviously because this is the else

Obviously because this is the else statement. So it simply returned this.

statement. So it simply returned this. Will it go to the next line? Obviously

Will it go to the next line? Obviously no. Because this condition is already

no. Because this condition is already true. Only one condition needs to be

true. Only one condition needs to be true. That's it. That's how your nested

true. That's it. That's how your nested if works.

if works. I would recommend you to build more and

I would recommend you to build more and more functions and not like functions

more functions and not like functions like real functions use cases using else

like real functions use cases using else and if statement because more you are

and if statement because more you are wellvered with if and else statement you

wellvered with if and else statement you can easily work with anything because

can easily work with anything because everywhere you will be using if else and

everywhere you will be using if else and nested if

nested if else okay so it is just a tip or you can

else okay so it is just a tip or you can say kind of homework for you so just do

say kind of homework for you so just do that okay now I know you are very very

that okay now I know you are very very very much wellvered with if condition

very much wellvered with if condition let Let me just tell you. Oh, finally my

let Let me just tell you. Oh, finally my favorite. So, now we're going to talk

favorite. So, now we're going to talk about

about loops. Loops are like data engineers

loops. Loops are like data engineers favorite thing. Favorite because let me

favorite thing. Favorite because let me just remove all the things. Okay. So,

just remove all the things. Okay. So, why why why loops are so important for

why why why loops are so important for data engineers? Because we work with big

data engineers? Because we work with big data. We get a lot of objects and we

data. We get a lot of objects and we need to perform iteration. Loops are

need to perform iteration. Loops are basically used for

basically used for iterations. Okay,

iterations. Real time example. Let's say you want to perform a loop or forget

say you want to perform a loop or forget about loop. Forget about loop. Let's say

about loop. Forget about loop. Let's say you need to read data from let's

you need to read data from let's say table one which is called orders.

say table one which is called orders. Okay. Then

Okay. Then products, then

customers, okay? Then let's say comments, then let's say

comments, then let's say um reviews like so many tables, right?

um reviews like so many tables, right? So these are your tables that you need

So these are your tables that you need to use while reading the data.

to use while reading the data. Basically, you need to read the data

Basically, you need to read the data from these tables. One way of doing it

from these tables. One way of doing it is simply perform the same code for

is simply perform the same code for individual table 1 2 3 4 5 here are

individual table 1 2 3 4 5 here are there are five in real world there can

there are five in real world there can be like hundreds of

be like hundreds of tables. Other thing what you can do is

tables. Other thing what you can do is you can simply run a loop a loop which

you can simply run a loop a loop which will

will perform iteration for all these items

perform iteration for all these items which are in this particular

array. Make sense? Make sense? Make sense?

sense? So it will simply perform iteration. So

So it will simply perform iteration. So iteration number one will be orders.

iteration number one will be orders. Iteration number two will be products,

Iteration number two will be products, then customers, then comments, then

then customers, then comments, then reviews. Make sense? Let's try to

reviews. Make sense? Let's try to understand this in deep with the help of

understand this in deep with the help of an example. Okay? And with the code as

an example. Okay? And with the code as well obviously. So very popular loop is

well obviously. So very popular loop is for loop. And you will be using for loop

for loop. And you will be using for loop at least I think 60% of the time or I

at least I think 60% of the time or I would say 80% of the time 20% of the

would say 80% of the time 20% of the time you will use while loop. And I will

time you will use while loop. And I will just talk about while loop as well. Uh

just talk about while loop as well. Uh it totally depends but yeah most in most

it totally depends but yeah most in most of the case you will use for loop. For

of the case you will use for loop. For loop is very simple. For loop is also

loop is very simple. For loop is also simple but you need to just manage while

simple but you need to just manage while loop and for in the for loop it is

loop and for in the for loop it is pretty much simple. You do not need to

pretty much simple. You do not need to perform iterations. So basically let's

perform iterations. So basically let's say you have a list. Let's say you have

say you have a list. Let's say you have a list. list is something like this um

a list. list is something like this um my

my list and it has values such as let's say

list and it has values such as let's say ABC or let's say orders

ABC or let's say orders orders

products products okay then you have let's say uh customers let's say three

let's say uh customers let's say three tables you want to simply run a loop on

tables you want to simply run a loop on top of this how you can just do that you

top of this how you can just do that you will simply say for Okay, for is like

will simply say for Okay, for is like for for loop. I I is nothing but just a

for for loop. I I is nothing but just a variable that you want to use as an I

variable that you want to use as an I iterator for I in on which we need to

iterator for I in on which we need to apply a loop on my list. Right? Simple.

apply a loop on my list. Right? Simple. This is a concept. Simply add colon go

This is a concept. Simply add colon go to the next line. Now I can simply say

to the next line. Now I can simply say print I because I want to see the value

print I because I want to see the value of I for

of I for each iteration. Right? It will simply

each iteration. Right? It will simply return values like this. Order,

return values like this. Order, products,

products, customers. Did I write this code? Print.

customers. Did I write this code? Print. So one option was for me print order.

So one option was for me print order. Okay.

Okay. Print

products and then print

print customers. Right? One option was this.

customers. Right? One option was this. If I just comment it out, one option was

If I just comment it out, one option was this or the second option was just

this or the second option was just simply run a loop. Simply run a

simply run a loop. Simply run a loop. I can simply run the loop.

loop. I can simply run the loop. Simple. That's the concept of

Simple. That's the concept of loop. Make sense. Okay, I hope it makes

loop. Make sense. Okay, I hope it makes sense. This is like very simple, very

sense. This is like very simple, very common example of for loop. We can even

common example of for loop. We can even use loop without this particular list.

use loop without this particular list. Let's say I want to run a loop on

Let's say I want to run a loop on specific um numbers. Let's say I want to

specific um numbers. Let's say I want to run a loop from start from one and it

run a loop from start from one and it should go till let's say 100. So for

should go till let's say 100. So for that we have something called as range

that we have something called as range function. I will simply write range and

function. I will simply write range and starting point is 1 and ending point is

starting point is 1 and ending point is 101. Why it always goes to n minus one.

101. Why it always goes to n minus one. Okay let me just print and you will see

Okay let me just print and you will see counting from 1 till 100.

counting from 1 till 100. See, so this is a range function that

See, so this is a range function that acts like an array. This is equivalent

acts like an array. This is equivalent to this one. 1 2 3 and till

to this one. 1 2 3 and till 100. Okay. So this is similar to this

100. Okay. So this is similar to this one. Make sense? This is similar to this

one. Make sense? This is similar to this one. This is like just a range

one. This is like just a range function. Just a range function. Okay.

function. Just a range function. Okay. Make sense? And let me just tell you one

Make sense? And let me just tell you one thing. You can even combine loops with

thing. You can even combine loops with if

if conditions. Really? Yes. Let's do that.

conditions. Really? Yes. Let's do that. So let's say you got like the previous

So let's say you got like the previous example. Let's say you got because this

example. Let's say you got because this is something similar to your data

is something similar to your data engineing stuff. So let's say this is

engineing stuff. So let's say this is your tables list. Let me just write

your tables list. Let me just write table. Okay. Now you want to run a loop

table. Okay. Now you want to run a loop on a table list and you need to check

on a table list and you need to check the table name because every time being

the table name because every time being a data engineer you cannot process all

a data engineer you cannot process all the data. You need to perform some

the data. You need to perform some validation steps as well. Right? So you

validation steps as well. Right? So you will simply say hey

will simply say hey um if my table name equals to equals to

um if my table name equals to equals to order then only I will just process data

order then only I will just process data otherwise not. This is the use case for

otherwise not. This is the use case for you as a data

you as a data engineer. Make sense? Very good. How you

engineer. Make sense? Very good. How you can just do that? So first of all it

can just do that? So first of all it will perform loop for I in table list.

will perform loop for I in table list. Perfect. Then it will simply provide the

Perfect. Then it will simply provide the value of I equals to order for first

value of I equals to order for first iteration. Very good. We will simply say

iteration. Very good. We will simply say if I equals to equals to

if I equals to equals to order equals to equals to order. Very

order equals to equals to order. Very good. Now let me just show you how we

good. Now let me just show you how we use upper and lower functions because

use upper and lower functions because the thing is it can be order it can

the thing is it can be order it can be order okay it can be order it can be

be order okay it can be order it can be anything right it depends upon the data

anything right it depends upon the data quality that we are getting so we just

quality that we are getting so we just need to make sure the errors we as a

need to make sure the errors we as a data engineer so we'll simply say I do

data engineer so we'll simply say I do lower so we'll simply convert the I to

lower so we'll simply convert the I to lower case and then we will compare it

lower case and then we will compare it like this equals to equals to order if

like this equals to equals to order if this is equals equals to order then

this is equals equals to order then print table order and obviously this is

print table order and obviously this is an example in the real life you will

an example in the real life you will perform your copy statement or you can

perform your copy statement or you can simply perform data reading you will

simply perform data reading you will simply write your code df equals to blah

simply write your code df equals to blah blah blah CSV read anything make sense

blah blah CSV read anything make sense are you are you getting my statement

are you are you getting my statement what I'm just using right now I'm just

what I'm just using right now I'm just trying you to relate with the data

trying you to relate with the data engineering how we are using Python with

engineering how we are using Python with data engineering that's why I'm focusing

data engineering that's why I'm focusing only on those stuff which are important

only on those stuff which are important for data engineers. Right? So let me

for data engineers. Right? So let me just run this and you will simply see

just run this and you will simply see table order. Now what happened? Now what

table order. Now what happened? Now what happened? Let me just show

happened? Let me just show you just to make you aware like how this

you just to make you aware like how this flows works. I will simply say else I

flows works. I will simply say else I will simply say

will simply say print no table

print no table order. Okay let me just run this.

order. Okay let me just run this. Perfect. Now let's understand what

Perfect. Now let's understand what happened. It simply iterated through

happened. It simply iterated through this list.

this list. For the first iteration, the value of I

For the first iteration, the value of I was order. Okay, it was in with capital

was order. Okay, it was in with capital O. We converted it and we just checked

O. We converted it and we just checked if it equals to equals to order simply

if it equals to equals to order simply return table order. This is done because

return table order. This is done because it will not go to else because this

it will not go to else because this condition is met. Second time this was

condition is met. Second time this was the value of I products, right? It went

the value of I products, right? It went here. It compared it. Is products equals

here. It compared it. Is products equals to equals to order? Obviously not. It

to equals to order? Obviously not. It failed. It went to this statement. else.

failed. It went to this statement. else. Very good. Then third iteration, the

Very good. Then third iteration, the value of I equals to equals to customer.

value of I equals to equals to customer. Okay, it compared it. Is it equal? No,

Okay, it compared it. Is it equal? No, it went here and it returned this. This

it went here and it returned this. This is how it is working for you. This is

is how it is working for you. This is how it is

how it is working. H okay. Makes sense. Makes

working. H okay. Makes sense. Makes sense. Makes sense. So

sense. Makes sense. So now now this is like all about for loop.

now now this is like all about for loop. Okay. And you can do a lot of stuff in

Okay. And you can do a lot of stuff in for loop. You can just even use like

for loop. You can just even use like multiple if conditions or you can even

multiple if conditions or you can even create another loop within this loop.

create another loop within this loop. How? You can even perform like loops

How? You can even perform like loops like

like this. Let's say you want

this. Let's say you want to create a loop on top of this list.

to create a loop on top of this list. Yes. So what will be the value of i?

Yes. So what will be the value of i? Equals to order. Makes sense. Common

Equals to order. Makes sense. Common sense. Now within

sense. Now within this you want to now run a loop on top

this you want to now run a loop on top of I. Are you serious bro? Hold on. I

of I. Are you serious bro? Hold on. I told you

told you that string is also like beh can be can

that string is also like beh can be can behave like an array right? Can behave

behave like an array right? Can behave like an array. So this is the value of

like an array. So this is the value of I. I want to run a loop on this

I. I want to run a loop on this particular string. Can can't I do that?

particular string. Can can't I do that? Now you will say yeah yeah we can do

Now you will say yeah yeah we can do that. So how we can just do that? Let me

that. So how we can just do that? Let me show you. I will simply say for I in

show you. I will simply say for I in table list I will first of all print

table list I will first of all print that just to show you print I

that just to show you print I immediately then I will simply say for

immediately then I will simply say for loop and this time let's create variable

loop and this time let's create variable called X in I in I then print X. So you

called X in I in I then print X. So you will see what happens see order. So

will see what happens see order. So first it just iterated through this

first it just iterated through this list. It got I equals to order. Then we

list. It got I equals to order. Then we created a loop on I. We get O R D E R.

created a loop on I. We get O R D E R. Same with products and same with

Same with products and same with customers as well. That's how we can

customers as well. That's how we can just run nested loops. Make sense? Make

just run nested loops. Make sense? Make sense? You can do a lot of stuff and my

sense? You can do a lot of stuff and my duty is you for like my duty is for you

duty is you for like my duty is for you to make you aware about all the things

to make you aware about all the things so that you can actually perform a lot

so that you can actually perform a lot of stuff and you do not need to worry

of stuff and you do not need to worry about the fundamentals and the concepts

about the fundamentals and the concepts because once you grab the concepts you

because once you grab the concepts you can practice it. You can try solving

can practice it. You can try solving questions. You can just do a lot of

questions. You can just do a lot of stuff that will make you a pro. That's

stuff that will make you a pro. That's all depends upon how much you practice.

all depends upon how much you practice. That's it. Because these stuff are same

That's it. Because these stuff are same everywhere. What I am trying to do I am

everywhere. What I am trying to do I am trying you I am trying to make you aware

trying you I am trying to make you aware these things about these things for data

these things about these things for data engineering domain. Okay. Yes we run

engineering domain. Okay. Yes we run loops like

loops like this. Got it? Very good. Now you will

this. Got it? Very good. Now you will say an Lamba for loops are really cool

say an Lamba for loops are really cool and we saw the power of it as well. What

and we saw the power of it as well. What about while loop? Like what what what

about while loop? Like what what what are loops man? Personally speaking, um

are loops man? Personally speaking, um you will hardly see anyone using Y loop

you will hardly see anyone using Y loop much. I would say 20% of the time you'll

much. I would say 20% of the time you'll be using Y loop but you will not be

be using Y loop but you will not be using Y loop a lot. Okay. And for with Y

using Y loop a lot. Okay. And for with Y loop you need to use break statements if

loop you need to use break statements if you are just if you're not iterating

you are just if you're not iterating something. So it is really really hard

something. So it is really really hard for you to just manage while loops.

for you to just manage while loops. Okay. Before talking about while loops,

Okay. Before talking about while loops, I need to talk about break and continue

I need to talk about break and continue statement. What are those statement?

statement. What are those statement? Those are really important. Once you

Those are really important. Once you understand those things, while loop is a

understand those things, while loop is a piece of cake for you. So basically,

piece of cake for you. So basically, let's take the same example. Okay, let's

let's take the same example. Okay, let's say this is a list. Okay, make sense? I

say this is a list. Okay, make sense? I know that in my list I have thousands of

know that in my list I have thousands of items. How much? Thousands. And I know

items. How much? Thousands. And I know that within that list I have only one

that within that list I have only one order table H and my duty is to

order table H and my duty is to just to just copy the orders

just to just copy the orders data. Okay. So what I would like to do I

data. Okay. So what I would like to do I would simply first of all I trade

would simply first of all I trade through all the items but the moment I

through all the items but the moment I find the orders table I want to break

find the orders table I want to break the loop immediately because I do not

the loop immediately because I do not want to go ahead after that

want to go ahead after that orders make sense make sense let's say

orders make sense make sense let's say let's put order in the between so that

let's put order in the between so that you can actually understand it let's say

you can actually understand it let's say like

like this like this so what it will do like

this like this so what it will do like what I want to achieve I want to

what I want to achieve I want to achieve. I want to iterate through this

achieve. I want to iterate through this list. I want to go

list. I want to go here. Is it equal to orders? No. Go

here. Is it equal to orders? No. Go ahead. Is it equal to order? Yes. Cut

ahead. Is it equal to order? Yes. Cut the loop. Break the loop. Immediately

the loop. Break the loop. Immediately break the

break the loop. Immediately. Oh, can we do that?

loop. Immediately. Oh, can we do that? Yeah, it's fun. I know. Let's do it. So,

Yeah, it's fun. I know. Let's do it. So, I will simply say for i

I will simply say for i in table

in table list. Okay.

list. Okay. I will simply say

I will simply say if

if I equals equals order and you will use

I equals equals order and you will use lower just to make sure case sensitivity

lower just to make sure case sensitivity is not affecting our code. If equals to

is not affecting our code. If equals to equals to order okay then

equals to order okay then break and obviously for you to see the

break and obviously for you to see the results I will simply first of all print

results I will simply first of all print the value of I let's see what will

the value of I let's see what will happen you will simply see two things

happen you will simply see two things not the customers perfect so what

not the customers perfect so what actually happened it started the loop it

actually happened it started the loop it printed the statement okay okay it

printed the statement okay okay it printed the statement and then it

printed the statement and then it compared it is it equal to order no so

compared it is it equal to order no so it didn't break it then for the second

it didn't break it then for the second value It printed the statement which is

value It printed the statement which is order and then it compared it. Is it

order and then it compared it. Is it equal to order? Break. It completed the

equal to order? Break. It completed the loop right away. Not completed. It just

loop right away. Not completed. It just break broke the loop. If I put print

break broke the loop. If I put print here, what should be the output? Just a

here, what should be the output? Just a quick question for you. If I say like

quick question for you. If I say like this, what output should you see? You

this, what output should you see? You have just 3

have just 3 seconds. Hm. Time up. You will just see

seconds. Hm. Time up. You will just see products. Not even products.

products. Not even products. So the thing is what actually

So the thing is what actually happened it started from here for I in

happened it started from here for I in tables list. Okay. So it compared it

tables list. Okay. So it compared it compared this with orders. Okay. Is it

compared this with orders. Okay. Is it equal to order?

equal to order? No. Then it compared it with order. Is

No. Then it compared it with order. Is it equal to order? Yes. So it break it.

it equal to order? Yes. So it break it. So break means it will not even go to

So break means it will not even go to the next line.

the next line. Oh, it will not even go to the next

Oh, it will not even go to the next line. It will break the whole code. It

line. It will break the whole code. It will break the loop and break do not

will break the loop and break do not execute the rest of the lines. It will

execute the rest of the lines. It will simply break it. Oh, okay. Yeah, makes

simply break it. Oh, okay. Yeah, makes sense. Now, what is continue statement?

sense. Now, what is continue statement? It is just opposite of break. Okay. What

It is just opposite of break. Okay. What does it mean? So, basically, let's take

does it mean? So, basically, let's take the example. Let's say you do not want

the example. Let's say you do not want to process order data. You want to

to process order data. You want to process all the other data. So what you

process all the other data. So what you will do? You will simply iterate through

will do? You will simply iterate through this list. Okay. This one, this one,

this list. Okay. This one, this one, this one. Make sense? Okay. Now what I

this one. Make sense? Okay. Now what I will do? If my data is products, it's

will do? If my data is products, it's fine. Simply print it. If my table name

fine. Simply print it. If my table name is order, continue. Continue means just

is order, continue. Continue means just skip that iteration.

skip that iteration. H just show us with example because then

H just show us with example because then only it will be much more you can

only it will be much more you can say visible and easy to digest. So

say visible and easy to digest. So basically for I in tables list that

basically for I in tables list that means it will iterate through each

means it will iterate through each entity 1 2 3 sorted sorted very good. So

entity 1 2 3 sorted sorted very good. So it will simply iterate through those

it will simply iterate through those items. I will

items. I will say

say if I do

if I do lower I dot lower equals to equals to

lower I dot lower equals to equals to order. Simply say

order. Simply say continue. Okay. And I will simply print

continue. Okay. And I will simply print the value here of I. If I run this, I

the value here of I. If I run this, I should not see order and I should only

should not see order and I should only see products. Why? It ran the loop.

see products. Why? It ran the loop. Okay. And then we said if this is equals

Okay. And then we said if this is equals to equals to order simply continue it.

to equals to order simply continue it. Continue means do not go ahead and do

Continue means do not go ahead and do not perform anything for this particular

not perform anything for this particular value which is I. And in this case it is

value which is I. And in this case it is order. Do not perform anything. So if it

order. Do not perform anything. So if it is products it will simply check it. Is

is products it will simply check it. Is it equals to order? No. Simply run rest

it equals to order? No. Simply run rest of the code. Simple. But if it is order

of the code. Simple. But if it is order it will simply say is it equal to equal

it will simply say is it equal to equal to order? Yes. Continue. Continue means

to order? Yes. Continue. Continue means just continue with the next iteration.

just continue with the next iteration. Do not run rest of the code. Do not run

Do not run rest of the code. Do not run the sprint I. No. Simply continue.

the sprint I. No. Simply continue. Skip. Okay. Makes sense. This is also

Skip. Okay. Makes sense. This is also easy. Yeah. And this is cool. Makes

easy. Yeah. And this is cool. Makes sense. Okay. Good. Now let's try to

sense. Okay. Good. Now let's try to understand the Y loop. Now let me just

understand the Y loop. Now let me just tell you what is Y loop and why do we

tell you what is Y loop and why do we use Y loop and how do we use Y loop. Now

use Y loop and how do we use Y loop. Now let's try to understand Y loops. Why

let's try to understand Y loops. Why loops are really handy when you do not

loops are really handy when you do not actually want to iterate but yeah you

actually want to iterate but yeah you want to iterate. Let me just tell you

want to iterate. Let me just tell you what's that. Basically um let's remove

what's that. Basically um let's remove this example. Okay let's say my x value

this example. Okay let's say my x value is equals to

is equals to 10. I want to iterate or let's say I

10. I want to iterate or let's say I want to perform my iterations till the

want to perform my iterations till the time my value

time my value is 10. I know you didn't understand

is 10. I know you didn't understand anything. Let me just explain. Wait. So

anything. Let me just explain. Wait. So basically I want to run a loop. Okay. I

basically I want to run a loop. Okay. I want to run a loop in for loop. I know I

want to run a loop in for loop. I know I can simply say for i in range

um let's say 1 till 11 because n minus one. Okay. I can do this. But if what if

one. Okay. I can do this. But if what if I want to just do the same stuff in y

I want to just do the same stuff in y loop? In y loop what I will do? I will

loop? In y loop what I will do? I will simply first of all create the variable

simply first of all create the variable x= to 10. Then I will simply say while

x= to 10. Then I will simply say while again it's English, right?

While x is less than 11, perform my thing. Perform my thing.

11, perform my thing. Perform my thing. Whatever I want to perform. Here's a

Whatever I want to perform. Here's a catch. The catch

catch. The catch is here for loop is iterating the values

is here for loop is iterating the values for us. While loop doesn't do that. So

for us. While loop doesn't do that. So we need to make sure once our work is

we need to make sure once our work is done for that iteration we need to

done for that iteration we need to iterate it. That means let's say this

iterate it. That means let's say this these are my lines of code that I want

these are my lines of code that I want to execute. Then I want to simply do

to execute. Then I want to simply do this x= x + 1. So that it would become

this x= x + 1. So that it would become two. It would become two and then three

two. It would become two and then three then four then five like this.

then four then five like this. And here in this case if we just perform

And here in this case if we just perform x= to x + 1 it will simply stop the

x= to x + 1 it will simply stop the loop. Why? My x is 10. The moment I have

loop. Why? My x is 10. The moment I have done my work it becomes 11 and this

done my work it becomes 11 and this condition is

condition is false. Make sense? Make sense? So how we

false. Make sense? Make sense? So how we actually run the loop? Let me just show

actually run the loop? Let me just show you in the real life. So let's say x= to

you in the real life. So let's say x= to 1 that is my starting point. Okay. I

1 that is my starting point. Okay. I will simply write

will simply write while x less than 11. That is my ending

while x less than 11. That is my ending point. Okay. This is starting point and

point. Okay. This is starting point and this is ending point. Simply do this

this is ending point. Simply do this print

print x. Now I cannot run this because the

x. Now I cannot run this because the moment I will run this, it will go in

moment I will run this, it will go in the infinite loop. Why? Just tell me one

the infinite loop. Why? Just tell me one thing. This is the loop. Okay, this is

thing. This is the loop. Okay, this is x. This is the value of x. What's the

x. This is the value of x. What's the value of x? One. This condition is true.

value of x? One. This condition is true. Yes. Print x. It will print one. Next

Yes. Print x. It will print one. Next time it will check the condition again.

time it will check the condition again. What's the value of x? one what it will

What's the value of x? one what it will print one third time, fourth time, fifth

print one third time, fourth time, fifth time, sixth time, all the times it is

time, sixth time, all the times it is true. So that means it will keep on keep

true. So that means it will keep on keep on running the same stuff and it will

on running the same stuff and it will simply give me like so many ones. Let me

simply give me like so many ones. Let me let me run this and you will see. Wow.

let me run this and you will see. Wow. And you can see how many ones I have. I

And you can see how many ones I have. I cannot even count because it is now an

cannot even count because it is now an infinite loop. You can say execution

infinite loop. You can say execution halted. Why? because it cannot handle

halted. Why? because it cannot handle this much of memory. So we need to say

this much of memory. So we need to say once our work is done once we have

once our work is done once we have printed the value simply say x= x + 1.

printed the value simply say x= x + 1. Now what is the value of x? It's 2. Is

Now what is the value of x? It's 2. Is it less than 11? Yes. Then 3 then 4 then

it less than 11? Yes. Then 3 then 4 then 5. It will go until 10. Let me just show

5. It will go until 10. Let me just show you. See 1 2 3 4 5 6 7 8 9 10. Simple.

you. See 1 2 3 4 5 6 7 8 9 10. Simple. Then the moment it becomes 11. This

Then the moment it becomes 11. This condition is false. It will stop

condition is false. It will stop here. Make sense? That's how your while

here. Make sense? That's how your while loop works. The only thing is you need

loop works. The only thing is you need to handle the iteration on your own.

to handle the iteration on your own. Okay? That's the only stress. And in for

Okay? That's the only stress. And in for loop, you do not need to do that. But

loop, you do not need to do that. But yes, while loop is also very handy.

yes, while loop is also very handy. Okay, while loop is also very handy. I

Okay, while loop is also very handy. I personally use while loop with break

personally use while loop with break statements. Let's say

statements. Let's say um even if I do not perform this one

um even if I do not perform this one like let's say I'm performing this. So

like let's say I'm performing this. So what I will do? I will simply apply an

what I will do? I will simply apply an if condition here. If

if condition here. If um let's say let's say I'm just running

um let's say let's say I'm just running an infinite loop. Let's say I will

an infinite loop. Let's say I will simply say while true or let's say 1= 2=

simply say while true or let's say 1= 2= to 1 because this is always true. Okay,

to 1 because this is always true. Okay, forget about this.

forget about this. So I'm just simply running this while 1=

So I'm just simply running this while 1= to equals to 1. Okay. And print hello.

to equals to 1. Okay. And print hello. Let's say I want to print hello. Okay.

Let's say I want to print hello. Okay. So how many times it will print hello?

So how many times it will print hello? Infinite times. Right? Infinite times.

Infinite times. Right? Infinite times. What I will do? I will simply

What I will do? I will simply say if or let's say anything, right?

say if or let's say anything, right? Anything.

Anything. uh let's say

uh let's say here here let's say x= 10 or let's say x

here here let's say x= 10 or let's say x equals to 100 100 is a good number I am

equals to 100 100 is a good number I am not checking my condition here because

not checking my condition here because it is always true but I'm saying x= x +

it is always true but I'm saying x= x + 1 okay so every time it is just

1 okay so every time it is just increasing the number here okay x = 101

increasing the number here okay x = 101 102 103 or let's say start with 1 okay

102 103 or let's say start with 1 okay it will become 2 3 4 5 6 7 8 9 10 I'll

it will become 2 3 4 5 6 7 8 9 10 I'll simply say

simply say if x

if x uh greater than 100 simply break it

uh greater than 100 simply break it simply break the loop now it will not go

simply break the loop now it will not go to the infinite number let's make a

to the infinite number let's make a number smaller so that so that you can

number smaller so that so that you can actually see so it will simply say hello

actually see so it will simply say hello 1 0 1 2 3 4 5 6 7 8 9 that means total

1 0 1 2 3 4 5 6 7 8 9 that means total 10 make sense so what it did we simply

10 make sense so what it did we simply break the loop we personally use while

break the loop we personally use while loop with break statements where we know

loop with break statements where we know that our loop can go to the infinite

that our loop can go to the infinite loop. We simply break it based on a

loop. We simply break it based on a condition. Make sense? Now I hope you

condition. Make sense? Now I hope you understood loops very much in detail.

understood loops very much in detail. The next thing that we going to cover is

The next thing that we going to cover is functions. Functions are like your

functions. Functions are like your non-negotiables. And I think before

non-negotiables. And I think before functions, we should master list. List

functions, we should master list. List data types. Then you will switch to

data types. Then you will switch to functions. Okay, let's first master list

functions. Okay, let's first master list because list is non-negotiable for data

because list is non-negotiable for data engineers. You have to be wellvered with

engineers. You have to be wellvered with list because list is you can say

list because list is you can say everything for you. All your data, all

everything for you. All your data, all the things everything is list. So, so

the things everything is list. So, so now let's try to master data structures

now let's try to master data structures and first of all like what are data

and first of all like what are data structures? So, basically data

structures? So, basically data structures are you can say the efficient

structures are you can say the efficient way to store and organize your data. So

way to store and organize your data. So let's say you have a data how you want

let's say you have a data how you want to store it and how you want to organize

to store it and how you want to organize it while storing the data that's where

it while storing the data that's where data structures come into the picture

data structures come into the picture because they help you to store your data

because they help you to store your data and organize it as well at the same

and organize it as well at the same time. Very popular data structure is

time. Very popular data structure is list in Python and being a data engineer

list in Python and being a data engineer there are some like data structures very

there are some like data structures very popular ones by the way all the data

popular ones by the way all the data structures are important but there are

structures are important but there are two to three which are the most

two to three which are the most important okay and list is one of those.

important okay and list is one of those. So basically what is a list? List as we

So basically what is a list? List as we all know list behaves similar to the

all know list behaves similar to the array or you can say 1D array and you

array or you can say 1D array and you have already worked with array in the

have already worked with array in the strings. Let's say you have data

strings. Let's say you have data something called as ids 1 2 3 4 5 where

something called as ids 1 2 3 4 5 where you actually do not have a specific kind

you actually do not have a specific kind of key assigned to it. You directly want

of key assigned to it. You directly want to store the values. See 1 2 3 4 5 6. It

to store the values. See 1 2 3 4 5 6. It can be table names as well as we have

can be table names as well as we have just seen right. So let's say you want

just seen right. So let's say you want to store this data. So in this

to store this data. So in this particular scenario you can efficiently

particular scenario you can efficiently use list and you can store this data in

use list and you can store this data in a list. And what's the advantage of it?

a list. And what's the advantage of it? Obviously it is storing your data. The

Obviously it is storing your data. The second is you can actually perform a lot

second is you can actually perform a lot of operations on top of it using so many

of operations on top of it using so many methods and using so many you can say

methods and using so many you can say functions that we have within the list.

functions that we have within the list. Basically we call those like list

Basically we call those like list operations that we have. And without

operations that we have. And without delaying, let me just show you what do

delaying, let me just show you what do we have in. So we are back in our

we have in. So we are back in our compiler. So first of all, let's create

compiler. So first of all, let's create a list. Okay, let's create a list. And

a list. Okay, let's create a list. And let's say my list looks like this. 1 2.

let's say my list looks like this. 1 2. Now the best thing is within this list,

Now the best thing is within this list, you can store anything. Let's say

you can store anything. Let's say numbers and even

numbers and even string. Anything. You can just store

string. Anything. You can just store anything. Let's say lamba. Okay. You can

anything. Let's say lamba. Okay. You can even store a list within the list. let's

even store a list within the list. let's say

say zero or let's say a

zero or let's say a a

a bb

bb cc. So this is a list which is holding

cc. So this is a list which is holding so many different types of data

so many different types of data obviously integer string and a list

obviously integer string and a list itself that means you can store anything

itself that means you can store anything within a list and I will store it in a

within a list and I will store it in a variable and I will simply say my

variable and I will simply say my list. Make sense?

list. Make sense? Make sense? So this is our list. So

Make sense? So this is our list. So what's the advantage of list? Again, you

what's the advantage of list? Again, you can perform all those indexing. Let's

can perform all those indexing. Let's revise those indexing. And now you

revise those indexing. And now you should be much familiar with those.

should be much familiar with those. Let's say I want to just fetch the first

Let's say I want to just fetch the first element. So I'll simply say zero. And

element. So I'll simply say zero. And I'll simply apply print

I'll simply apply print here. And I should

here. And I should see only one. Very good. Let's say I

see only one. Very good. Let's say I want to fetch 0 1 2 3 4th element. I

want to fetch 0 1 2 3 4th element. I will simply see a list

will simply see a list right very good let's say within this

right very good let's say within this list I want to

list I want to fetch first element I will simply

fetch first element I will simply say

say one BB make sense so we are actually

one BB make sense so we are actually performing indexing within the list as

performing indexing within the list as well that's up to us now we already know

well that's up to us now we already know these things we have already seen this

these things we have already seen this and we can also like perform slicing

and we can also like perform slicing similar to this one let's say I want to

similar to this one let's say I want to fetch only zero

fetch only zero tell three. So it will simply give me 0

tell three. So it will simply give me 0 1 and two. Right? So all these stuff you

1 and two. Right? So all these stuff you already know. Let's talk about something

already know. Let's talk about something new in your code. Let's say if you're

new in your code. Let's say if you're working in an organization, you will see

working in an organization, you will see that people use something called as

that people use something called as minus sign here. Let's say they are

minus sign here. Let's say they are using something like this minus 3 and

using something like this minus 3 and then column. Do you know what it will

then column. Do you know what it will do? It will simply give

do? It will simply give you 1 2 and three last three elements.

you 1 2 and three last three elements. Really? Yes, let's run this. See an

Really? Yes, let's run this. See an lamba and this list last three elements.

lamba and this list last three elements. Let me just replace this with a normal

Let me just replace this with a normal function like normal number so that you

function like normal number so that you will not be confused. So see these three

will not be confused. So see these three elements. What does it mean? What does

elements. What does it mean? What does it mean? Like when we say minus three,

it mean? Like when we say minus three, what does it actually mean? This is

what does it actually mean? This is fine. Okay, this is fine. This means

fine. Okay, this is fine. This means like n this means n because we already

like n this means n because we already know that it will be the length of the

know that it will be the length of the list which is length of my list. So

list which is length of my list. So whenever you write minus 3 do you know

whenever you write minus 3 do you know what python will do behind the scenes?

what python will do behind the scenes? Python will simply treat this thing like

Python will simply treat this thing like this my

this my list. Okay. And then within this it will

list. Okay. And then within this it will say length of my list.

say length of my list. length

length of my list. Okay. Then minus three. Oh,

of my list. Okay. Then minus three. Oh, then whatever number we have here, we

then whatever number we have here, we already know that it will simply perform

already know that it will simply perform length. So it will simply do like

length. So it will simply do like this. So this is the actual thing that

this. So this is the actual thing that it is performing under the hood. And you

it is performing under the hood. And you can even print it just to see it is

can even print it just to see it is exactly the same.

See, so whenever you see minus3 sign, okay, whenever you see minus three sign,

okay, whenever you see minus three sign, you can replace it with total length of

you can replace it with total length of the uh list minus that number like not

the uh list minus that number like not minus like exactly that number that is

minus like exactly that number that is minus 3. So it's up to you why do we use

minus 3. So it's up to you why do we use it? We use it a lot. Let's say you want

it? We use it a lot. Let's say you want to fetch last 10 digits of a mobile

to fetch last 10 digits of a mobile number. If you have if you are because

number. If you have if you are because in the real world you will be working

in the real world you will be working with data, right? And in that particular

with data, right? And in that particular data you have a column for mobile number

data you have a column for mobile number and within that you have different

and within that you have different different area codes. You have different

different area codes. You have different different country codes. But you just

different country codes. But you just need to fetch the 10 digits last 10

need to fetch the 10 digits last 10 digits. In that particular scenario you

digits. In that particular scenario you can simply perform like this like let's

can simply perform like this like let's say minus 10 and that's it. You will

say minus 10 and that's it. You will simply see minus 10. Obviously we do not

simply see minus 10. Obviously we do not have 10 elements. So you are seeing all

have 10 elements. So you are seeing all these elements. But in reality, in

these elements. But in reality, in reality, in that column, you will just

reality, in that column, you will just see last 10 items or you can say last 10

see last 10 items or you can say last 10 digits of that particular column. Make

digits of that particular column. Make sense? It's up to you uh if you just

sense? It's up to you uh if you just want to treat it like this. So how does

want to treat it like this. So how does it work behind the scenes? Like how we

it work behind the scenes? Like how we need to just use it. So let's say let's

need to just use it. So let's say let's perform like minus three so that you can

perform like minus three so that you can actually see the results. So what it

actually see the results. So what it will do? So this starts from behind. So

will do? So this starts from behind. So it will simply say minus one. Okay, this

it will simply say minus one. Okay, this is minus one. So if we are starting from

is minus one. So if we are starting from the beginning, we start from zero. So

the beginning, we start from zero. So this is zero. If we want to start from

this is zero. If we want to start from the behind, it is minus one. So this is

the behind, it is minus one. So this is minus1. This is -2. This is minus 3.

minus1. This is -2. This is minus 3. Okay. And this will go till the

Okay. And this will go till the beginning of the list. Like maybe like

beginning of the list. Like maybe like you can say the last number that it has.

you can say the last number that it has. So the last number is zero, right? So it

So the last number is zero, right? So it will not include zero. So it will simply

will not include zero. So it will simply cover minus3, minus2, minus1 and that's

cover minus3, minus2, minus1 and that's it. It is like a little bit confusing

it. It is like a little bit confusing but when you just use it you will love

but when you just use it you will love this method a lot because it is very

this method a lot because it is very easy. You need to simply find last three

easy. You need to simply find last three digits simply write minus three and

digits simply write minus three and that's it. It is really easy but yeah in

that's it. It is really easy but yeah in the beginning it seems a little

the beginning it seems a little confusing but it is not. It is not.

confusing but it is not. It is not. Okay. Let me just tell you one more

Okay. Let me just tell you one more thing. So let's say you have this list.

thing. So let's say you have this list. Let me add more numbers here. Let's say

Let me add more numbers here. Let's say four 5 6. Okay. Now I want to simply

four 5 6. Okay. Now I want to simply fetch the list but I want to skip the

fetch the list but I want to skip the number by two instead of by one. What do

number by two instead of by one. What do I mean? If we write something like

this my list colon what it will do? It will

list colon what it will do? It will simply return me the full list. Make

simply return me the full list. Make sense? And how it is doing that? It is

sense? And how it is doing that? It is simply starting from zero. It is going

simply starting from zero. It is going till uh n and it is simply iterating

till uh n and it is simply iterating through one number like only the gap of

through one number like only the gap of one. If I

one. If I say

say two like this obviously you do not need

two like this obviously you do not need to use comma for the simplicity I'm just

to use comma for the simplicity I'm just telling you. If you write something like

telling you. If you write something like two you need a kind of iteration. So for

two you need a kind of iteration. So for that particular purpose what it will do

that particular purpose what it will do it will simply start from one it will

it will simply start from one it will directly jump onto the second number not

directly jump onto the second number not to the next one. So it will simply say

to the next one. So it will simply say an then it will jump onto the third then

an then it will jump onto the third then it will jump onto the five. That's how

it will jump onto the five. That's how it works. So let's see in the code you

it works. So let's see in the code you simply need another colon and that's it.

simply need another colon and that's it. See 1 3 5 that's it. So that means you

See 1 3 5 that's it. So that means you can actually decide the iterated value

can actually decide the iterated value as well. You can actually decide the

as well. You can actually decide the gap. If I say three, it will simply jump

gap. If I say three, it will simply jump to lamba directly. See one lamba and

to lamba directly. See one lamba and then

then five. Make sense? Very good. So this is

five. Make sense? Very good. So this is the third one and this is optional. If

the third one and this is optional. If you do not define it, by default it is

you do not define it, by default it is one. If you want to define it, you can

one. If you want to define it, you can define it's up to you. So this is all

define it's up to you. So this is all about like slicing and indexing. Let's

about like slicing and indexing. Let's see some of the operations that we have

see some of the operations that we have because we need to see it. Let's say you

because we need to see it. Let's say you want to add something into your ex

want to add something into your ex existing list. Can you do that? Yes, you

existing list. Can you do that? Yes, you can do that using append method. I will

can do that using append method. I will simply say my

simply say my list dot append and I want to add let's

list dot append and I want to add let's say hero. So what it will do? It will

say hero. So what it will do? It will simply add that particular element at

simply add that particular element at the end of the script after six.

the end of the script after six. Let me print as

well. Oops. Oh yeah, because it appended it. We need to just say print my

it. We need to just say print my list. Uh uh uh. So this is done. So it

list. Uh uh uh. So this is done. So it has appended the

has appended the data. Okay. And now we are just checking

data. Okay. And now we are just checking the list like how does it look like now.

the list like how does it look like now. Okay. Perfect. It has added hero at the

Okay. Perfect. It has added hero at the end.

end. Why? Why? There is a very important

Why? Why? There is a very important concept here. Why? Because

mutable. H what are mutable? What are mutable? That means

mutable? What are mutable? That means the value can be changed.

the value can be changed. We can change the

We can change the value or values of a list. Here we

value or values of a list. Here we change the value of a list. How? Because

change the value of a list. How? Because we added the element. We do not need to

we added the element. We do not need to say something like this. My

say something like this. My list

list equals my

list.append something like this. Because we perform this thing when our list are

we perform this thing when our list are not mutable or you can say immutable but

not mutable or you can say immutable but our lists are mutable. That means the

our lists are mutable. That means the moment we perform

moment we perform this it will actually automatically add

this it will actually automatically add this thing here and we do not need to

this thing here and we do not need to say hey my list equals to this thing

say hey my list equals to this thing that means it will automatically perform

that means it will automatically perform this step here. Wow. Yes. So now one

this step here. Wow. Yes. So now one more thing if you want to add hero after

more thing if you want to add hero after one can we do that because append method

one can we do that because append method will like every time insert or you can

will like every time insert or you can say add the data at the end. So if you

say add the data at the end. So if you want to insert a data at a particular

want to insert a data at a particular location we have a function called

location we have a function called insert. So it is called my list

insert. So it is called my list dotinsert. Okay. And first you will

dotinsert. Okay. And first you will define the location. I will simply say 1

define the location. I will simply say 1 index because one is standing at zero

index because one is standing at zero index. I want to add it at the 1 index

index. I want to add it at the 1 index and currently at the 1 index we have two

and currently at the 1 index we have two right. So one comma

right. So one comma hero. So if I simply run this I should

hero. So if I simply run this I should see hero after one. And here we are

see hero after one. And here we are seeing at the end as well. Why? Because

seeing at the end as well. Why? Because it was added before. See very good.

it was added before. See very good. Now if we want to let's say delete a

Now if we want to let's say delete a delete an item. Can we do that? Yes. So

delete an item. Can we do that? Yes. So we have a function called pop. My list

we have a function called pop. My list dot pop. That's it. So what it will do?

dot pop. That's it. So what it will do? What element it will delete? First let's

What element it will delete? First let's see. You will get to

see. You will get to know. It deleted hero. But why? How does

know. It deleted hero. But why? How does it know it needs to delete hero? So the

it know it needs to delete hero? So the thing is dotpop method will

thing is dotpop method will automatically delete or you can say drop

automatically delete or you can say drop or you can say pop your data from

or you can say pop your data from the end of your list by default. Okay.

the end of your list by default. Okay. So if you just want to delete the data

So if you just want to delete the data from the last just use dot pop. That's

from the last just use dot pop. That's it. That's it. That's it. That's it. We

it. That's it. That's it. That's it. We rarely delete stuff from the list but

rarely delete stuff from the list but yeah you should know about this. So

yeah you should know about this. So these are some of the functions that we

these are some of the functions that we use a lot with the list and list are

use a lot with the list and list are like your bread and butter and let me

like your bread and butter and let me just talk about a

just talk about a very you can

very you can say oftenly used question or you can say

say oftenly used question or you can say scenario. Let's say you have this this

scenario. Let's say you have this this list. Let me remove this one. Okay.

list. Let me remove this one. Okay. Let's say you have this list. If you

Let's say you have this list. If you want to reverse this list, how you can

want to reverse this list, how you can just do that? How you can do that? If

just do that? How you can do that? If you just want to reverse this list, um,

you just want to reverse this list, um, one way like there are so many ways by

one way like there are so many ways by the way and we can obviously achieve

the way and we can obviously achieve this thing using loop. If you will use

this thing using loop. If you will use your brain, you can simply run a loop on

your brain, you can simply run a loop on this particular list and from the back

this particular list and from the back instead of from the starting. Can we do

instead of from the starting. Can we do that? Yeah, let's do that. So let's say

that? Yeah, let's do that. So let's say for i in my list. Okay. So this will

for i in my list. Okay. So this will simply run the loop on the list, right?

simply run the loop on the list, right? Yes, it will do that. But what you need

Yes, it will do that. But what you need to do here, you need to tell the loop

to do here, you need to tell the loop that you want to run the loop from the

that you want to run the loop from the end, not from the beginning. How you can

end, not from the beginning. How you can do that? You can simply use a function

do that? You can simply use a function called reversed. And then you can simply

called reversed. And then you can simply say run and you will simply see 6 5 4 3

say run and you will simply see 6 5 4 3 2 1. That means we have some functions

2 1. That means we have some functions available to reverse a list. We can even

available to reverse a list. We can even say like this. Let's

say like this. Let's say my list dot

say my list dot reverse and we can just comment it out.

reverse and we can just comment it out. And if I simply print the list, it will

And if I simply print the list, it will simply make changes in the existing

simply make changes in the existing list. Uh print my list. See 6 5 4 3 2 1.

list. Uh print my list. See 6 5 4 3 2 1. But this loop method is handy when you

But this loop method is handy when you do not want to make changes in the list

do not want to make changes in the list but you just want to use a kind of

but you just want to use a kind of reverse function during runtime so that

reverse function during runtime so that you can simply make the changes

you can simply make the changes temporarily. Okay. But if you just want

temporarily. Okay. But if you just want to permanently reverse this uh the list

to permanently reverse this uh the list you can simply use this method so that

you can simply use this method so that you can actually get the result like

you can actually get the result like this. So we have dot reverse method to

this. So we have dot reverse method to make the permanent changes. Reverse

make the permanent changes. Reverse method during runtime. That's it.

method during runtime. That's it. There's one more way to make the changes

There's one more way to make the changes like this. So what's the way? So

like this. So what's the way? So basically if you simply write something

basically if you simply write something like this my list. First of all let me

like this my list. First of all let me just show you. So this is a list. Okay.

just show you. So this is a list. Okay. 1 2 3 4 5 6. Let me clear this. If you

1 2 3 4 5 6. Let me clear this. If you say colon colon minus one, it will give

say colon colon minus one, it will give you the same results. And let me just

you the same results. And let me just show

show you. Print my

list. Wait what? print my list uh colon colon minus one. Oh yeah,

list uh colon colon minus one. Oh yeah, because we just need to do print here.

because we just need to do print here. We are just simply printing the same

We are just simply printing the same stuff here and we can simply comment it

stuff here and we can simply comment it out. Simply run this and yeah perfect.

out. Simply run this and yeah perfect. So what it is doing right now? So

So what it is doing right now? So basically it is simply putting it

basically it is simply putting it here length of list. But why? Every time

here length of list. But why? Every time it puts you can say

it puts you can say zero right it is still doing that so

zero right it is still doing that so what we going to achieve we going to

what we going to achieve we going to simply iterate our list by minus one so

simply iterate our list by minus one so every time it will simply perform minus

every time it will simply perform minus one so let's say it is starting from one

one so let's say it is starting from one okay so it will simply go to six because

okay so it will simply go to six because we are just simply performing and you

we are just simply performing and you can say starting from minus one it will

can say starting from minus one it will simply go to six okay then it will

simply go to six okay then it will simply uh put here one is two but it

simply uh put here one is two but it will simply perform minus one after six

will simply perform minus one after six not after one. So that is the confusion

not after one. So that is the confusion that you need to clear. So first of all

that you need to clear. So first of all it will start from six six and then it

it will start from six six and then it will go to five simple and then four 3 2

will go to five simple and then four 3 2 1. This way you can perform reverse

1. This way you can perform reverse operation on list using indexing as

operation on list using indexing as well. It's up to you. It's up to you. So

well. It's up to you. It's up to you. So this was all about your list basically

this was all about your list basically list operations. And now I think the

list operations. And now I think the next thing that we should know is list

next thing that we should know is list comprehension. List comprehension is

comprehension. List comprehension is really important and I will first show

really important and I will first show you working with loops and list and then

you working with loops and list and then I will just show you list comprehension.

I will just show you list comprehension. So basically it is very simple and

So basically it is very simple and before that let's summarize this

before that let's summarize this indexing. I know it is a little

indexing. I know it is a little confusing but it is very easy. So let's

confusing but it is very easy. So let's say this is your list. Okay let me clear

say this is your list. Okay let me clear all the clutter. So let's say this is

all the clutter. So let's say this is your list. If you perform especially

your list. If you perform especially like

like negative list slicing is like a little

negative list slicing is like a little bit confusing. So you can simply say my

bit confusing. So you can simply say my list. Okay. And if you simply say minus

list. Okay. And if you simply say minus 3 that means it is equivalent to

3 that means it is equivalent to total minus3 and this is the end. This

total minus3 and this is the end. This is the total length of the list. Okay.

is the total length of the list. Okay. Or for the simplicity you can simply say

Or for the simplicity you can simply say it as like start. This is a starting

it as like start. This is a starting point. Okay. This is the stopping point

point. Okay. This is the stopping point start and

start and stop. So the starting point is minus3

stop. So the starting point is minus3 and it is the second analogy that we use

and it is the second analogy that we use in the real life minus three. That means

in the real life minus three. That means it will start from the minus3 elements

it will start from the minus3 elements from the behind from the let's say from

from the behind from the let's say from the right hand side. So it will simply

the right hand side. So it will simply go here 1 2 3. So this is the starting

go here 1 2 3. So this is the starting point and it will go till the end of the

point and it will go till the end of the list. That's it. 4 5 6 and we should see

list. That's it. 4 5 6 and we should see that thing. Oops. So let me say

print. Perfect. That's it. And we also learned about that we can also perform

learned about that we can also perform skipping. So if we just say let's say

skipping. So if we just say let's say two, it will skip all the elements which

two, it will skip all the elements which are like you can say it will skip two,

are like you can say it will skip two, four and six. And we also learned about

four and six. And we also learned about if we just want to reverse a list, we

if we just want to reverse a list, we can simply say like this minus one.

can simply say like this minus one. Perfect. Quick revision. That's it. Very

Perfect. Quick revision. That's it. Very good. Now let's actually understand the

good. Now let's actually understand the list comprehension. It's really

list comprehension. It's really important. So let's say this is our

important. So let's say this is our list. Okay. Let's say this is our list.

list. Okay. Let's say this is our list. Now you need to create a new list. Okay.

Now you need to create a new list. Okay. This is right now empty. Okay. This is

This is right now empty. Okay. This is the new list. Now you just want to

the new list. Now you just want to create a new list and you want to

create a new list and you want to populate this new list with the square

populate this new list with the square of every number. square of every

of every number. square of every number. Obviously, you would need to use

number. Obviously, you would need to use a loop so that you can just use every

a loop so that you can just use every value and you can just actually perform

value and you can just actually perform square on each number. So, what's the

square on each number. So, what's the traditional approach? It's like this for

traditional approach? It's like this for i in my

i in my list. Okay. And then it will simply say

list. Okay. And then it will simply say because I is the number. So, I will

because I is the number. So, I will simply say uh new

simply say uh new list dot append. And what is the append

list dot append. And what is the append value? I hrix I. Why? Because it will

value? I hrix I. Why? Because it will simply perform square of every number

simply perform square of every number and it will append the data in this list

and it will append the data in this list for all the i value. Right? Let me just

for all the i value. Right? Let me just show you the results as well. New

show you the results as well. New list and we will have new list having

list and we will have new list having square of every number. So we

square of every number. So we write so many lines of code whenever you

write so many lines of code whenever you want to use right like like this thing.

want to use right like like this thing. So first we create the empty list then

So first we create the empty list then we create a loop then we perform append

we create a loop then we perform append function. What if I can just tell you

function. What if I can just tell you that all the three lines of code can be

that all the three lines of code can be replaced by just one line of code.

replaced by just one line of code. That's where your list comprehension

helps. So what does it mean? So basically let me just comment it out.

basically let me just comment it out. Okay. And let me just show you that I

Okay. And let me just show you that I can create a new list.

can create a new list. Same way I created it. So this is my

Same way I created it. So this is my empty list. I can directly fill the data

empty list. I can directly fill the data within this. That means I can literally

within this. That means I can literally write my code within this list. Wow.

write my code within this list. Wow. Really? Yes. What I can do? I can simply

Really? Yes. What I can do? I can simply write a loop for I in my list. Okay. And

write a loop for I in my list. Okay. And then in the starting. So this is

then in the starting. So this is basically the a kind of you can say

basically the a kind of you can say um itraable

um itraable function basically a loop that you are

function basically a loop that you are applying on an object which is holding a

applying on an object which is holding a kind of iterable items. So you can

kind of iterable items. So you can simply say for i in this blah blah

simply say for i in this blah blah this. So this is simply like running a

this. So this is simply like running a kind of loop. Whatever you want to

kind of loop. Whatever you want to return you will write in the beginning

return you will write in the beginning you will simply say I a str i. That's

you will simply say I a str i. That's it. If you just say

it. If you just say print new

print new list you will see the same stuff.

list you will see the same stuff. Wow. Let's say you want to also check if

Wow. Let's say you want to also check if the numbers are odd or even. If they are

the numbers are odd or even. If they are even then only fill the data in the list

even then only fill the data in the list otherwise

otherwise not. Wow. How can we do that? So you

not. Wow. How can we do that? So you have liberty to apply condition after

have liberty to apply condition after your iterable object. You can only apply

your iterable object. You can only apply condition after the loop. So I will

condition after the loop. So I will simply say if I

simply say if I mod 2 and it's a good practice to put it

mod 2 and it's a good practice to put it in the braces equals to equals to 0.

in the braces equals to equals to 0. That is the condition for even. That

That is the condition for even. That means if your number can be easily

means if your number can be easily divisible by two and the remainder will

divisible by two and the remainder will be zero. That means it's an even number.

be zero. That means it's an even number. That's basic mathematics that you should

That's basic mathematics that you should know. Let's see the results. So I will

know. Let's see the results. So I will simply see

simply see 4 16 and 36. That's it. Because only 2,

4 16 and 36. That's it. Because only 2, 4 and six are the even numbers and other

4 and six are the even numbers and other are not even numbers. Wow.

are not even numbers. Wow. Yes. This is the power of list

Yes. This is the power of list compilation. You can even add multiple

compilation. You can even add multiple conditions. Say you want to add one more

conditions. Say you want to add one more condition which is you do not want to

condition which is you do not want to just find the square of six. You do not

just find the square of six. You do not want to include this number. So you can

want to include this number. So you can simply say

simply say if I not equals to 6. Make sense? This

if I not equals to 6. Make sense? This is our second condition. We'll simply

is our second condition. We'll simply run it and we'll simply see four and 16

run it and we'll simply see four and 16 only because six is not included. So

only because six is not included. So this way you can add multiple

this way you can add multiple conditions. So this is your output that

conditions. So this is your output that you will add in your list. This is a

you will add in your list. This is a kind of iterator that you run and these

kind of iterator that you run and these are the conditions that if you want to

are the conditions that if you want to apply these conditions on top of it. So

apply these conditions on top of it. So can you see so many lines of code are

can you see so many lines of code are aggregated in just one line of code.

aggregated in just one line of code. That's it. Otherwise you would be

That's it. Otherwise you would be creating multiple if first of all you

creating multiple if first of all you would create a for loop. Then you would

would create a for loop. Then you would create if condition then another if

create if condition then another if condition and then you will be just

condition and then you will be just returning the value and appending it in

returning the value and appending it in the new list. So this is all done within

the new list. So this is all done within just like one single line of code.

just like one single line of code. That's the power of it. Make sense?

That's the power of it. Make sense? Makes sense. So this is your list and

Makes sense. So this is your list and definitely it is really handy and it's

definitely it is really handy and it's again personal choice. Okay. Both the

again personal choice. Okay. Both the ways are good and both the ways are used

ways are good and both the ways are used in your code. If you like this way, use

in your code. If you like this way, use it. If you like this way, use it. I know

it. If you like this way, use it. I know this is simple and beginners prefer

this is simple and beginners prefer this. Okay. But once you are like

this. Okay. But once you are like writing so many lines of code, you will

writing so many lines of code, you will simply say hey I can simply apply this

simply say hey I can simply apply this but if you are like code is already

but if you are like code is already really complex then you can simply use

really complex then you can simply use this just to avoid any confusion. So

this just to avoid any confusion. So both are really good. Okay. So that is

both are really good. Okay. So that is the power of list comprehension that

the power of list comprehension that this will actually aggregate your multi-

this will actually aggregate your multi- lines of code into just one or two. Make

lines of code into just one or two. Make sense? Yeah. I think we have covered

sense? Yeah. I think we have covered almost everything that we should know

almost everything that we should know about list. Now let's cover

about list. Now let's cover the second the most the most the most

the second the most the most the most important data structure which is which

important data structure which is which is dictionary. Let me just tell you

is dictionary. Let me just tell you about that. Dictionary is the second

about that. Dictionary is the second most or I can even say like it is

most or I can even say like it is equally

equally used data structure as we use like list

used data structure as we use like list dictionary is like very much handy for

dictionary is like very much handy for data engineers. Why? Because of its

data engineers. Why? Because of its unique data storage you can say

unique data storage you can say architecture. architecture not really

architecture. architecture not really architecture let me just tell you so

architecture let me just tell you so within the list we store the data within

within the list we store the data within you can say 1D array you can say within

you can say 1D array you can say within the list like 1 2 3 4 5 wow what I

the list like 1 2 3 4 5 wow what I handwriting 1 2 3 4 5 okay but we do not

handwriting 1 2 3 4 5 okay but we do not have any kind of meaning to these values

have any kind of meaning to these values we do not know like what is one like

we do not know like what is one like what is two what is three dictionary

what is two what is three dictionary helps us to add some context text to our

helps us to add some context text to our values. So let's say I want to say x =

values. So let's say I want to say x = to 1, y = 2, z = to 3 like this. I want

to 1, y = 2, z = to 3 like this. I want to store my data in the key value pairs.

to store my data in the key value pairs. That's where dictionary is very handy

That's where dictionary is very handy and it works really well with JSON

and it works really well with JSON objects as well like JavaScript object

objects as well like JavaScript object notation because whatever data you are

notation because whatever data you are working with in data engineering, if

working with in data engineering, if you're making API calls, don't worry,

you're making API calls, don't worry, we'll just talk about that as well. So

we'll just talk about that as well. So you will be just getting the response in

you will be just getting the response in the form of JSON that is a kind of

the form of JSON that is a kind of dictionary in which like data is stored.

dictionary in which like data is stored. So now let me just tell you how data

So now let me just tell you how data will be stored in dictionary. It will

will be stored in dictionary. It will look like this. It has curly braces.

look like this. It has curly braces. Okay, it has like curly braces instead

Okay, it has like curly braces instead of square brackets. It will simply say

of square brackets. It will simply say key. Key is let's say x and it has the

key. Key is let's say x and it has the value called one. then

value called one. then second

second y then two. So this way it holds all the

y then two. So this way it holds all the variables or you can say all the keys.

variables or you can say all the keys. If you want to store your data like

If you want to store your data like this, you should always go to dictionary

this, you should always go to dictionary and dictionary is like your go-to tool

and dictionary is like your go-to tool for this or you can say basically data

for this or you can say basically data structure. Let's see in the code like

structure. Let's see in the code like how we can just work with dictionary and

how we can just work with dictionary and what are those functions that we use or

what are those functions that we use or you can say what are those operations

you can say what are those operations that we should use with dictionary. So

that we should use with dictionary. So let's try to understand dictionary. I

let's try to understand dictionary. I will simply create dictionary called uh

will simply create dictionary called uh my

my dictionary.

My dictionary okay make sense? So now what I will do I

okay make sense? So now what I will do I will simply create curly braces and then

will simply create curly braces and then I will simply say x and the value of x

I will simply say x and the value of x is let's say one. If I want to store

is let's say one. If I want to store integer if string I can simply say like

integer if string I can simply say like this. Uh sorry like this. Okay, I want

this. Uh sorry like this. Okay, I want to store integer. Then I will simply say

to store integer. Then I will simply say comma that is the next value. I will

comma that is the next value. I will simply say y and then two then z and

simply say y and then two then z and then three. Okay. Now I can simply print

then three. Okay. Now I can simply print my

dictionary. Let's see what we get. So this is a dictionary. Okay, make sense.

this is a dictionary. Okay, make sense. It behaves almost similar to list. You

It behaves almost similar to list. You can perform all the operations that you

can perform all the operations that you perform on list and obviously with the

perform on list and obviously with the different style because this is not

different style because this is not exactly same as um this your list. So if

exactly same as um this your list. So if we just want basically dictionary are

we just want basically dictionary are also mutable. You can just make changes

also mutable. You can just make changes directly to the dictionary. It is it

directly to the dictionary. It is it behaves similar to your list. So let's

behaves similar to your list. So let's say I want to change the value of x. I

say I want to change the value of x. I can simply

can simply say my dictionary. Okay.

say my dictionary. Okay. And how to change the value? Here's the

And how to change the value? Here's the thing. So you can simply use something

thing. So you can simply use something called as square brackets. Here we do

called as square brackets. Here we do not use indexes. In the list we use

not use indexes. In the list we use indexes. Here we use keys because every

indexes. Here we use keys because every value is assigned to a key. Make sense?

value is assigned to a key. Make sense? Because here we are not relying on the

Because here we are not relying on the index. Here one is assigned to

index. Here one is assigned to X. Okay. We can even change the order.

X. Okay. We can even change the order. Still we can just perform all the things

Still we can just perform all the things using the keys because we are accessing

using the keys because we are accessing the keys. So I will simply say my

the keys. So I will simply say my dictionary and

dictionary and x equals to let's say 10. Okay, let's

x equals to let's say 10. Okay, let's see what it will do. Okay, we can see

see what it will do. Okay, we can see that the value is changed. Why? Because

that the value is changed. Why? Because these are

these are mutable H. Okay, now if you just want to

mutable H. Okay, now if you just want to remove or let's say um delete any kind

remove or let's say um delete any kind of key, you can simply do that

of key, you can simply do that using pop method my dictionary. Okay.

using pop method my dictionary. Okay. and then dotpop. But here's the thing,

and then dotpop. But here's the thing, you cannot say pop because this is not

you cannot say pop because this is not relying on the index. This will not

relying on the index. This will not automatically remove your data from the

automatically remove your data from the back. It will simply say remove the key

back. It will simply say remove the key which is called Z. Let's see what do we

which is called Z. Let's see what do we get. We will simply get only two things

get. We will simply get only two things X and Y. That's it. That's it. This is

X and Y. That's it. That's it. This is your dictionary. And this is so so so

your dictionary. And this is so so so handy. This is so cool. Some of the

handy. This is so cool. Some of the things that I want to show you, you can

things that I want to show you, you can even print all the keys. Let's say you

even print all the keys. Let's say you have a very big dictionary and you just

have a very big dictionary and you just want to make sure what are the keys

want to make sure what are the keys present in that dictionary. You can

present in that dictionary. You can simply say print dictionary dot

simply say print dictionary dot keys. You will only get keys. Okay. And

keys. You will only get keys. Okay. And let's not pop this. Let's see xyz. See

let's not pop this. Let's see xyz. See it is saying that you have dictionary

it is saying that you have dictionary keys x y z and it will simply return

keys x y z and it will simply return that in the form of list. Make sense?

that in the form of list. Make sense? Now if you just want to see the values

Now if you just want to see the values you can simply like this.

Perfect values are 10 2 3 but it doesn't make any sense to see the values because

make any sense to see the values because obviously we cannot understand like what

obviously we cannot understand like what values assigned for 10 or what is a key

values assigned for 10 or what is a key for 10. So instead we use something

for 10. So instead we use something called as keys or sorry items. So if you

called as keys or sorry items. So if you just run this you will actually see x is

just run this you will actually see x is assigned with 10 y with two z with

assigned with 10 y with two z with three. Make sense? This is the power of

three. Make sense? This is the power of items. This is the power of items. So

items. This is the power of items. So this is a dictionary nothing special but

this is a dictionary nothing special but yeah it becomes very handy when you are

yeah it becomes very handy when you are just working with data engineering stuff

just working with data engineering stuff and you will be working a lot with

and you will be working a lot with dictionary that's why it is easy to

dictionary that's why it is easy to master plus easy to work with and

master plus easy to work with and obviously it can have like multiple

obviously it can have like multiple inherited dictionaries as well. So let's

inherited dictionaries as well. So let's say I create a dictionary and add um

say I create a dictionary and add um demo and I will simply create a

demo and I will simply create a dictionary within this and how it will

dictionary within this and how it will behave. I will simply add XYZ let's say

behave. I will simply add XYZ let's say within this as well. Let's add it here.

within this as well. Let's add it here. And I will simply rename it

And I will simply rename it A then B then C. Okay, let's try to see

A then B then C. Okay, let's try to see this.

this. print my

dictionary. Okay, so it has this particular dictionary, right? Make

particular dictionary, right? Make sense? Now if you just want to access

sense? Now if you just want to access element B, how you will do that? So we

element B, how you will do that? So we know that if you just want to access any

know that if you just want to access any key, we access like this demo. So if you

key, we access like this demo. So if you just print this demo only, you will get

just print this demo only, you will get the output like this. Now within this

the output like this. Now within this demo you will simply say item D. That's

demo you will simply say item D. That's it. Similar to your list instead of just

it. Similar to your list instead of just passing it like uh a kind of index you

passing it like uh a kind of index you are passing the keys. That's it. That's

are passing the keys. That's it. That's it. Make sense? Make sense? This way you

it. Make sense? Make sense? This way you can actually fetch the data which is

can actually fetch the data which is having a hierarchy of the dictionary.

having a hierarchy of the dictionary. You can actually fetch the data and

You can actually fetch the data and that's what we do in data engineering.

that's what we do in data engineering. Okay, good, good, good. What do we have

Okay, good, good, good. What do we have next? Um, okay. Okay. I already told

next? Um, okay. Okay. I already told this. Okay. Oh, that's it. Very good.

this. Okay. Oh, that's it. Very good. Now, let's

Now, let's see the very important, not so

see the very important, not so important, but yeah, it becomes very

important, but yeah, it becomes very important sometimes. So, let's talk

important sometimes. So, let's talk about sets. Now, what is a set? Let me

about sets. Now, what is a set? Let me just tell you, it is very interesting.

just tell you, it is very interesting. It is very interesting. Now let's talk

It is very interesting. Now let's talk about the sets. Sets welcome to the

about the sets. Sets welcome to the mathematics area of Python. Okay. So if

mathematics area of Python. Okay. So if you have studied mathematics in

you have studied mathematics in school and if not you would have bro

school and if not you would have bro because I think sets were there until

because I think sets were there until class 10th but again yeah I know like

class 10th but again yeah I know like people love mathematics by the way I

people love mathematics by the way I have done my bachelor's in mathematics.

have done my bachelor's in mathematics. Okay but yeah I don't know about sets

Okay but yeah I don't know about sets much because I last studied sets in

much because I last studied sets in class 10th only. I think class 11th as

class 10th only. I think class 11th as well. I don't know what I did in

well. I don't know what I did in bachelor's in mathematics. They were

bachelor's in mathematics. They were just teaching some theories and how to

just teaching some theories and how to prove one is greater than zero. I was

prove one is greater than zero. I was like what? I already know

like what? I already know this. So by the way data structure sets

this. So by the way data structure sets sets is really really handy but it can

sets is really really handy but it can sometimes

sometimes um make you confused. Why? Because of

um make you confused. Why? Because of its structure like physical structure.

its structure like physical structure. We already know lists are like this.

We already know lists are like this. Okay, dictionaries are like this. Sets

Okay, dictionaries are like this. Sets are also like this. What? How can it be

are also like this. What? How can it be like how can we store the data and how

like how can we store the data and how we will distinguish like it is a

we will distinguish like it is a dictionary or it is a set. So

dictionary or it is a set. So basically we store the data which do not

basically we store the data which do not have any kind of keys and we simply use

have any kind of keys and we simply use set for that. you will simply say an if

set for that. you will simply say an if we just want to save or store the data

we just want to save or store the data without any keys we can simply use list

without any keys we can simply use list right yes but if you just want to

right yes but if you just want to perform some mathematical operations

perform some mathematical operations what are the mathematical operations

what are the mathematical operations that we use in sets let me just give you

that we use in sets let me just give you some nostalgic heads so basically you

some nostalgic heads so basically you would seen that A equals 1 2 3 B = 4 5 6

would seen that A equals 1 2 3 B = 4 5 6 right if I want to apply a union B we

right if I want to apply a union B we can do that. If I want to apply A

can do that. If I want to apply A intersection B we can do that. So all

intersection B we can do that. So all these things are possible with the help

these things are possible with the help of

of sets. The most amazing thing is you do

sets. The most amazing thing is you do not need to worry about duplicates

not need to worry about duplicates within sets. It will automatically

within sets. It will automatically remove duplicates from your

remove duplicates from your set. Really?

set. Really? Yes.

Yes. Automatically. Oh. And you can even just

Automatically. Oh. And you can even just perform so many other things as well

perform so many other things as well that I will just show you right now.

that I will just show you right now. Okay. So if you are not good at

Okay. So if you are not good at mathematics do not worry. Now you know

mathematics do not worry. Now you know Python you can perform all those things

Python you can perform all those things things using sets. Let me just show you.

things using sets. Let me just show you. So let's clear this stuff and let's

So let's clear this stuff and let's create a set. I will simply say my set

create a set. I will simply say my set equals 1 2 3 4 5. Okay. And you will say

equals 1 2 3 4 5. Okay. And you will say this is not a dictionary. No. Are you

this is not a dictionary. No. Are you sure? Yes. Can we validate it? Yes, I

sure? Yes. Can we validate it? Yes, I will simply say

will simply say print type of my

print type of my set and I will simply get a set. See

set and I will simply get a set. See this is a set. Okay, very good. If I

this is a set. Okay, very good. If I want to print it, I will simply say

want to print it, I will simply say print my

print my set. Okay, if I add five five five55 so

set. Okay, if I add five five five55 so many times. If I just print it, I will

many times. If I just print it, I will simply see it only one time because it

simply see it only one time because it will automatically remove the

will automatically remove the duplicates. Wow, this is amazing. This

duplicates. Wow, this is amazing. This feature is not available in list. This

feature is not available in list. This is only available in set. Wow, this is

is only available in set. Wow, this is amazing. Let's say this is my set or

amazing. Let's say this is my set or let's call it as a. Okay, let's create

let's call it as a. Okay, let's create another set and let's call it as let's

another set and let's call it as let's say 10

say 10 11

11 2 5.

2 5. Okay, if I want to perform union, how I

Okay, if I want to perform union, how I can just do that? It's very simple. I'll

can just do that? It's very simple. I'll simply say perform print A dot union B.

simply say perform print A dot union B. And you will see

And you will see uh wait did I oh I didn't close the

uh wait did I oh I didn't close the set. Perfect. So now what is A union B?

set. Perfect. So now what is A union B? Obviously I'm not going to teach you

Obviously I'm not going to teach you mathematics. So in union we

mathematics. So in union we get all the nonre repeating or you can

get all the nonre repeating or you can say

say non-duplicates plus the l. So wait wait

non-duplicates plus the l. So wait wait wait anala teach some mathematics. So

wait anala teach some mathematics. So basically it will first of all fetch the

basically it will first of all fetch the a it will simply say 1 2 3 4 5 sorted.

a it will simply say 1 2 3 4 5 sorted. It will bring it. Okay perfect. Then it

It will bring it. Okay perfect. Then it will go to B and it will bring only

will go to B and it will bring only those elements which are not present in

those elements which are not present in A plus which are already present in A

A plus which are already present in A because it is already there. So it will

because it is already there. So it will simply grab 10 11 that's it and 1 2 3 4

simply grab 10 11 that's it and 1 2 3 4 5 is coming from A. So if you just take

5 is coming from A. So if you just take the V diagram of it let's say this is

the V diagram of it let's say this is your A. Okay let's say this is your

your A. Okay let's say this is your B. Make sense? So this is your A union B

B. Make sense? So this is your A union B the whole

the whole part see and this is common part will

part see and this is common part will appear only

appear only once make sense very good now let's try

once make sense very good now let's try to apply intersection now what is

to apply intersection now what is intersection let me just tell you first

intersection let me just tell you first of

of all intersection is only those elements

all intersection is only those elements which are common in both okay so only

which are common in both okay so only this area will appear in the result and

this area will appear in the result and what is that Or you can say what what

what is that Or you can say what what are those items which are common in both

are those items which are common in both 2 3 55. So we will simply see 235. I

2 3 55. So we will simply see 235. I will simply say

will simply say intersection and I will simply see 235.

intersection and I will simply see 235. Perfect.

Perfect. Now if I want to let's say remove the

Now if I want to let's say remove the set item how I can just do that. I will

set item how I can just do that. I will simply say a dot remove and whatever I

simply say a dot remove and whatever I want to remove let's say I want to

want to remove let's say I want to remove a dot remove two. Okay. If I

remove a dot remove two. Okay. If I simply say print a, you will not see two

simply say print a, you will not see two in that because we have removed it. Make

in that because we have removed it. Make sense? Similarly, you can add as well.

sense? Similarly, you can add as well. If you just want to let's say add um 20,

If you just want to let's say add um 20, it will simply add

it will simply add 20 at the end. H makes sense. Now is the

20 at the end. H makes sense. Now is the tricky question. Let's say you created a

tricky question. Let's say you created a set. Okay, you created let there's a

set. Okay, you created let there's a variable and this is the code written.

variable and this is the code written. What is it? Is it an empty dictionary or

What is it? Is it an empty dictionary or is it an empty

is it an empty set? Boom. Just tell me. So the answer

set? Boom. Just tell me. So the answer is it is an empty dictionary. I can even

is it is an empty dictionary. I can even show

you type of f. See so anal how we can create an empty

See so anal how we can create an empty set. For that you simply need to use set

set. For that you simply need to use set function. Then only you will get the

function. Then only you will get the empty set. See. Oh wow. This was

empty set. See. Oh wow. This was amazing. Yeah. Yeah. Yeah. Yeah. So this

amazing. Yeah. Yeah. Yeah. Yeah. So this was all about your sets. Now let's talk

was all about your sets. Now let's talk about one more data structure that we

about one more data structure that we have. It is called tpple. Let's talk

have. It is called tpple. Let's talk about Now let's talk about tpple. Tupel

about Now let's talk about tpple. Tupel is another very useful data structure

is another very useful data structure but not actually very useful because the

but not actually very useful because the thing is first of all let me just show

thing is first of all let me just show you the physical structure of it. It is

you the physical structure of it. It is like curly uh not curly round braces

like curly uh not curly round braces like one 2 3. Now it behaves exactly

like one 2 3. Now it behaves exactly same as a list and we data engineers

same as a list and we data engineers work more with list. So what we do what

work more with list. So what we do what do we do? We simply convert a tpple into

do we do? We simply convert a tpple into a list and we perform all the things.

a list and we perform all the things. Yeah, that's that's how we work. You

Yeah, that's that's how we work. You will say, hey, okay, we can just apply

will say, hey, okay, we can just apply all the things. What if we just want to

all the things. What if we just want to return the result in the form of duple?

return the result in the form of duple? Yeah, you can just again convert a list

Yeah, you can just again convert a list into a duple. Oh, this way the advantage

into a duple. Oh, this way the advantage of this is you will not feel confused

of this is you will not feel confused whenever you just want to apply some

whenever you just want to apply some things. Let's say I want to add the data

things. Let's say I want to add the data in the list. I will simply remember

in the list. I will simply remember append mode. I do not need to remember

append mode. I do not need to remember the method that we use in tpple, right?

the method that we use in tpple, right? I want to remove the data. I will simply

I want to remove the data. I will simply remember pop method. I do not need to

remember pop method. I do not need to remember delete method. So these things

remember delete method. So these things will make you let's say work with Python

will make you let's say work with Python with more ease because you do not need

with more ease because you do not need to mug up your mind between different

to mug up your mind between different different data structures. But yeah, you

different data structures. But yeah, you can easily convert your TPLE into list.

can easily convert your TPLE into list. And that's it. That's it. Now let's see

And that's it. That's it. Now let's see with the help of code as well so that

with the help of code as well so that you can actually understand. Let's see.

you can actually understand. Let's see. Boom. Let's create our first list. Oh,

Boom. Let's create our first list. Oh, not list tpple my two. I will simply say

not list tpple my two. I will simply say my two and I will simply say 1 2 3 4 5.

my two and I will simply say 1 2 3 4 5. Okay, let's print

it. So my tpple. So 1 2 3 4 5. Now let's say I want to add one data like add one

say I want to add one data like add one item and blah blah blah. I want to do

item and blah blah blah. I want to do all those stuff. So what I will do? We

all those stuff. So what I will do? We have methods in tpple. We have like

have methods in tpple. We have like delete method and so many methods. But

delete method and so many methods. But what I will do? So I will simply say my

what I will do? So I will simply say my top list tpple list equals list of my

top list tpple list equals list of my top. So this will simply convert this

top. So this will simply convert this into a list and then I can simply say my

into a list and then I can simply say my T

T list dot

list dot append. Okay let's say I want to add

append. Okay let's say I want to add six. Perfect. I can simply print it my T

six. Perfect. I can simply print it my T list. And then I want to convert my T

list. And then I want to convert my T list into a tpple. Right? I will simply

list into a tpple. Right? I will simply say my tpple or let's say my

say my tpple or let's say my top equals tpple

top equals tpple of my list. Make sense? And then print

of my list. Make sense? And then print this as

well my top. Let's run this code.

top. Let's run this code. Uh name tupless is not

Uh name tupless is not defined.

defined. Really? What's wrong? Oh, wait, wait,

Really? What's wrong? Oh, wait, wait, wait,

wait, wait. Tup list is not defined. Uh, top.

wait. Tup list is not defined. Uh, top. Oh, it's my it's my not

Oh, it's my it's my not list. Okay. My list is not defined. Did

list. Okay. My list is not defined. Did you mean my top list? Yeah. Yeah. Yeah.

you mean my top list? Yeah. Yeah. Yeah. I mean my top

I mean my top list.

list. Print. Perfect. So now you can see we

Print. Perfect. So now you can see we first of all printed the same tpple.

first of all printed the same tpple. Okay. Then we added the item with the

Okay. Then we added the item with the help of list and then we again convert

help of list and then we again convert it into tpple and we return the result.

it into tpple and we return the result. In most of the scenarios you would not

In most of the scenarios you would not be required to convert it back to a

be required to convert it back to a tuple. Trust me. But if you have to have

tuple. Trust me. But if you have to have to convert it you have the method ready

to convert it you have the method ready you can easily convert your tpple into a

you can easily convert your tpple into a like list into a tpple back. Okay. So

like list into a tpple back. Okay. So that's how you work with tpple. H. So we

that's how you work with tpple. H. So we have covered almost all the important

have covered almost all the important data structures that we have for data

data structures that we have for data engineering. list and dictionary are

engineering. list and dictionary are your top

your top priorities that you have to master. Now

priorities that you have to master. Now let's try to master something very

let's try to master something very important functions. Okay,

important functions. Okay, functions are like non-negotiables for

functions are like non-negotiables for anyone not even like for data engineers

anyone not even like for data engineers anyone. Let's try to understand like

anyone. Let's try to understand like what are functions? How we can just

what are functions? How we can just create functions? Let's do that. Talk

create functions? Let's do that. Talk about the functions. Basically what is a

about the functions. Basically what is a function? function basically in like

function? function basically in like let's say in short I would say functions

let's say in short I would say functions help

help you from rewriting the code again and

you from rewriting the code again and again okay let's understand it with an

again okay let's understand it with an example so let's say you have written 50

example so let's say you have written 50 lines of code

lines of code okay 50 lines of

code now within your program within your program you need to reuse these 50 lines

program you need to reuse these 50 lines of code again. Okay. Okay. Now what you

of code again. Okay. Okay. Now what you will do? You will simply copy and paste.

will do? You will simply copy and paste. Okay. And you will simply just add these

Okay. And you will simply just add these lines of code in your program. Okay. One

lines of code in your program. Okay. One time is good. Okay. Just do that. Let's

time is good. Okay. Just do that. Let's do this. Then let's say again you need

do this. Then let's say again you need to do that. Okay. Then again, then

to do that. Okay. Then again, then again, then

again, then again let's say you need to use these 50

again let's say you need to use these 50 lines of code 10 times in your code. So

lines of code 10 times in your code. So you are literally adding 500 lines of

you are literally adding 500 lines of code in your program. 500 lines of code.

code in your program. 500 lines of code. Wow. What if I say that you can reduce

Wow. What if I say that you can reduce these numbers from 500 to 55 or let's

these numbers from 500 to 55 or let's say

say 260. How is this possible? Basically, it

260. How is this possible? Basically, it is possible because these 50 lines of

is possible because these 50 lines of code will

be registered under a function and you can call this function directly using

can call this function directly using one line of code. And if you just want

one line of code. And if you just want to use this 50 lines of code 10 times,

to use this 50 lines of code 10 times, you will just make 10 calls and each

you will just make 10 calls and each call will hardly take only one line. So

call will hardly take only one line. So that's why you will end up having only

that's why you will end up having only 60 co 60 lines of code. Plus, it will

60 co 60 lines of code. Plus, it will promote readability.

promote readability. Okay. So, An Lamba, what if I want to

Okay. So, An Lamba, what if I want to make some changes in these lines? Then

make some changes in these lines? Then is it possible? Yes. Because you add

is it possible? Yes. Because you add something called as parameters in the

something called as parameters in the functions. Oh, that's the whole concept

functions. Oh, that's the whole concept of function. Instead of rewriting the

of function. Instead of rewriting the code again and again, it will simply ask

code again and again, it will simply ask you, hey, you can simply reuse the code

you, hey, you can simply reuse the code using a function. I know you are really

using a function. I know you are really excited to see this in Python. So let me

excited to see this in Python. So let me actually show you everything using the

actually show you everything using the code because you will understand better

code because you will understand better using the code. Let me

using the code. Let me just so here we are. So first of all let

just so here we are. So first of all let me just take an example. Let's say you

me just take an example. Let's say you have written a code let's say similar to

have written a code let's say similar to this x= to 10 and you are saying

if greater than [Music]

[Music] 10

10 else print

um I don't know okay so if I Just run this. Okay, I got I don't know. Let's

this. Okay, I got I don't know. Let's say you want to reuse this code in your

say you want to reuse this code in your program. You will simply copy and paste

program. You will simply copy and paste it. This time you will simply say 12 and

it. This time you will simply say 12 and you will simply run it. Perfect. Then

you will simply run it. Perfect. Then let's say third time. This time it is 15

let's say third time. This time it is 15 or let's say

or let's say 20. Okay. Again. Let's

say five. So why I am adding these lines of code

So why I am adding these lines of code again and again? Because you want to use

again and again? Because you want to use it. Yeah. But I do not want to use it

it. Yeah. But I do not want to use it like this. So that's where you can use a

like this. So that's where you can use a function. So what I will do, I will

function. So what I will do, I will simply copy this code. Okay. And I will

simply copy this code. Okay. And I will remove everything. I will create a

remove everything. I will create a function from scratch. How you can

function from scratch. How you can create a function? You will simply say

create a function? You will simply say def that is the syntax. Okay. Defen

def that is the syntax. Okay. Defen function name. My function is my

function name. My function is my function.

function. Perfect. Then you simply need to write

Perfect. Then you simply need to write your logic. Whatever you want to do, the

your logic. Whatever you want to do, the same stuff. Whatever you want to do,

same stuff. Whatever you want to do, simply write the logic and that's it.

simply write the logic and that's it. That's it. If I run this, it will simply

That's it. If I run this, it will simply create the function for me. If I want to

create the function for me. If I want to call this function, I will use something

call this function, I will use something like this. My function and then that's

like this. My function and then that's it. You will see the output. Now, x is

it. You will see the output. Now, x is not defined. Obviously, we need to first

not defined. Obviously, we need to first define the x because x is not there.

define the x because x is not there. x equals to let's say 10. Let's call

x equals to let's say 10. Let's call this. Perfect. We got the output. Let's

this. Perfect. We got the output. Let's say I want to call this function for

say I want to call this function for different value of x. What I can do? I

different value of x. What I can do? I can simply do like this x= to 11 and

can simply do like this x= to 11 and then my

then my function. Perfect. See, very good. If I

function. Perfect. See, very good. If I just want to make this call for a

just want to make this call for a different value of x, I can do the same

different value of x, I can do the same stuff x= to 12 and do this. It is nice

stuff x= to 12 and do this. It is nice but we can optimize this by adding a

but we can optimize this by adding a parameter. Okay, let me just remove

parameter. Okay, let me just remove everything. Let's say I want to run this

everything. Let's say I want to run this function for a different value of X

function for a different value of X every time. Okay, so what I will do, I

every time. Okay, so what I will do, I will even remove X from here. I will

will even remove X from here. I will simply create a parameter inside this

simply create a parameter inside this function and I will simply name it as

function and I will simply name it as P_X. That means parameter X and then I

P_X. That means parameter X and then I will simply use that parameter inside

will simply use that parameter inside this function as well. And now you will

this function as well. And now you will say hey An lamba that is fine but how we

say hey An lamba that is fine but how we can provide the value of this parameter.

can provide the value of this parameter. We will provide this value during

We will provide this value during calling the function. I will simply say

calling the function. I will simply say 20 and it's good. Wow. Let's say you

20 and it's good. Wow. Let's say you want to run this function for a

want to run this function for a different value. You will simply

different value. You will simply say my function

say my function 30. Okay. Makes sense. Make sense. Now

30. Okay. Makes sense. Make sense. Now in real life you always return something

in real life you always return something from a function. Okay we know that we

from a function. Okay we know that we are printing the values that is fine but

are printing the values that is fine but in most of the cases in the real world

in most of the cases in the real world as well you will return something from a

as well you will return something from a function. Let's say you want to return

function. Let's say you want to return px just to check like what is the value

px just to check like what is the value of it. You can simply run it. You will

of it. You can simply run it. You will simply say let me first remove this as

simply say let me first remove this as well. You will simply say hey an nothing

well. You will simply say hey an nothing is returned.

is returned. Yeah, there's a difference

Yeah, there's a difference between

between print and return. Okay, print will

print and return. Okay, print will simply display the output. But return

simply display the output. But return can be stored. Oh, we cannot store this

can be stored. Oh, we cannot store this statement greater than 10. We can store

statement greater than 10. We can store this return statement. Let's say you

this return statement. Let's say you want to store the output of this

want to store the output of this function, not output basically the

function, not output basically the return value of this function in a

return value of this function in a variable. I will simply say

return value equals to this and I can even print it. let's say returned value

even print it. let's say returned value or even I can use it let's say in my

or even I can use it let's say in my upcoming code

upcoming code right perfect that's how we store the

right perfect that's how we store the value that's why we always say return

value that's why we always say return command is even more important than your

command is even more important than your print command because in the real world

print command because in the real world you do not need to display anything

you do not need to display anything using functions you actually return

using functions you actually return something make sense this was very basic

something make sense this was very basic example let's level up okay how how how

example let's level up okay how how how let's add multiple parameters okay let's

let's add multiple parameters okay let's say

say Let's

Let's say you are using multiple parameters

say you are using multiple parameters for any reason. Okay. And you are even

for any reason. Okay. And you are even returning it. Let me remove if else

returning it. Let me remove if else because that concept is clear for you.

because that concept is clear for you. And now we are just focusing on

And now we are just focusing on something critical. So I will simply say

something critical. So I will simply say py and I will simply add another

py and I will simply add another parameter here as well. Make sense? Now

parameter here as well. Make sense? Now if I just make a call to this function,

if I just make a call to this function, it will throw me an error. Why? Because

it will throw me an error. Why? Because it will say bro your function needs two

it will say bro your function needs two parameters. You are passing only one. So

parameters. You are passing only one. So it is not fair. Pass the second one as

it is not fair. Pass the second one as well. I will simply say 30. Now it is

well. I will simply say 30. Now it is good. Very good. Now the thing is let's

good. Very good. Now the thing is let's use print. Okay. Just to see the

use print. Okay. Just to see the results.

So perfect. Very good. Now can we do the reverse of it? Let's say

reverse of it? Let's say um even before reversing it. Let's say

um even before reversing it. Let's say you do not want to pass this value 30.

you do not want to pass this value 30. You will only pass the value for

You will only pass the value for px. Can we do this? Yes. That's where

px. Can we do this? Yes. That's where the use of default values come into the

the use of default values come into the picture. You can actually decide the

picture. You can actually decide the default values of these parameters so

default values of these parameters so that even if your user is missing any

that even if your user is missing any value, your code will not fail. You can

value, your code will not fail. You can simply say 30. So you will simply see 20

simply say 30. So you will simply see 20 30. Why? Because it will use the default

30. Why? Because it will use the default value if it is not being passed from

value if it is not being passed from here. But you cannot do the reverse of

here. But you cannot do the reverse of it. That means you cannot do like this.

it. That means you cannot do like this. Let's say this is py or or wait what if

Let's say this is py or or wait what if you pass the value here if your variable

you pass the value here if your variable is already given it will simply override

is already given it will simply override it see this will take the priority this

it see this will take the priority this 30 will only be used if this value is

30 will only be used if this value is not passed okay I hope like it was

not passed okay I hope like it was understood but still I wanted to discuss

understood but still I wanted to discuss okay now let's do that particular

okay now let's do that particular scenario

scenario where you do not

where you do not have the third variable parameter and

have the third variable parameter and you are passing that variable, what will

you are passing that variable, what will happen in this case? It will simply

happen in this case? It will simply throw an error. But in some

throw an error. But in some scenarios, in some scenarios, your user

scenarios, in some scenarios, your user can pass multiple you can say inputs or

can pass multiple you can say inputs or if you're just using a function to get

if you're just using a function to get the data as an input. You can get like

the data as an input. You can get like so many values, right? So in that

so many values, right? So in that scenario, what you do? You simply make

scenario, what you do? You simply make use of something called as ax and then

use of something called as ax and then you define only one parameter. So what

you define only one parameter. So what it will do? It

it will do? It will take so many values. You can pass

will take so many values. You can pass so many values now. There's no limit

so many values now. There's no limit because asterisk will take care of it.

because asterisk will take care of it. Asterisk will convert all these values

Asterisk will convert all these values in a

in a tuple. Wow. And I can even show you bro.

tuple. Wow. And I can even show you bro. Let me just run this. See this is a

Let me just run this. See this is a tpple. You can even show

tpple. You can even show the you can

the you can say data type of it. I will simply say

say data type of it. I will simply say type of

type of px and you will see tpple. Wow. So now

px and you will see tpple. Wow. So now there's no need to worry. You can pass

there's no need to worry. You can pass one 2 100,000 so many

one 2 100,000 so many parameters. Okay. That makes sense. That

parameters. Okay. That makes sense. That makes sense.

makes sense. Now I want to talk about something more

Now I want to talk about something more critical. Let's level up a little bit

critical. Let's level up a little bit more. Let's say so here you are simply

more. Let's say so here you are simply passing the values right? You are not

passing the values right? You are not passing the keys. So you are not

passing the keys. So you are not actually worrying about the keys. What

actually worrying about the keys. What if you want to assign the keys as well?

if you want to assign the keys as well? Let's say x= 20, y = to 60, z= to 70 and

Let's say x= 20, y = to 60, z= to 70 and so on. And you want to use these keys as

so on. And you want to use these keys as well. In that scenario, in that

well. In that scenario, in that scenario, let's say you are passing your

scenario, let's say you are passing your function like this. X= to 20, Y= to 60,

function like this. X= to 20, Y= to 60, Z= to 70. Like this. Now what it will

Z= to 70. Like this. Now what it will do? It will not obviously take it Y. If

do? It will not obviously take it Y. If you just run this, it will simply say,

you just run this, it will simply say, hey, what is this X= to 20? I don't know

hey, what is this X= to 20? I don't know X. I don't know these keys. Then you

X. I don't know these keys. Then you simply add one more axis. What it will

simply add one more axis. What it will do? It will convert this into a

do? It will convert this into a dictionary. It will convert it like

dictionary. It will convert it like this.

this. X 20 then

X 20 then Y 60 and so on. Wow. Let me run this and

Y 60 and so on. Wow. Let me run this and you will see this is a dictionary and

you will see this is a dictionary and type is dictionary. So if you even want

type is dictionary. So if you even want to print let's say keys of it, you can

to print let's say keys of it, you can even use it. It's not just you just want

even use it. It's not just you just want to use values, you can even use keys.

to use values, you can even use keys. See keys.

Boom. This is really helpful. This is really helpful. And I hope it makes

really helpful. And I hope it makes sense to use these

sense to use these things. This is the best way to work

things. This is the best way to work with a function. Okay, make sense? Very

with a function. Okay, make sense? Very good. Now it's time to discuss something

good. Now it's time to discuss something more important and those are called

more important and those are called lambda functions. Basically, there's a

lambda functions. Basically, there's a big debate because some people do like

big debate because some people do like functions like normal functions like

functions like normal functions like this. Some like lambda functions. I

this. Some like lambda functions. I personally like these functions more. It

personally like these functions more. It promotes readability and it gives you

promotes readability and it gives you flexibility to write your complex logics

flexibility to write your complex logics as well. Lambda functions are like mini

as well. Lambda functions are like mini functions, lightweight functions that

functions, lightweight functions that you should use if you do not have much

you should use if you do not have much stuff to do. Let's say you are writing a

stuff to do. Let's say you are writing a function and your function is doing an

function and your function is doing an addition. Okay, this is your function.

addition. Okay, this is your function. It takes two parameters XY and just

It takes two parameters XY and just print.

print. Okay, it just print or let's say return

Okay, it just print or let's say return x + y or let's say

x + y or let's say return x + y. Simple. If you just call

return x + y. Simple. If you just call it, you will simply say addition 1020

it, you will simply say addition 1020 and this is return. So, we need to save

and this is return. So, we need to save it in a variable. So, I'll simply say

it in a variable. So, I'll simply say variable and print

variable. Okay, makes sense. Makes sense. Makes sense. Makes

sense. Makes sense. Makes sense. Okay, 30. Makes sense. So this is

sense. Okay, 30. Makes sense. So this is one way of doing it. What is the other

one way of doing it. What is the other way of doing it? You can even create

way of doing it? You can even create lambda function. Now this is really

lambda function. Now this is really important and sometime it becomes really

important and sometime it becomes really useful because if you are doing

useful because if you are doing something like this that we just did, it

something like this that we just did, it doesn't make any sense to just create a

doesn't make any sense to just create a function and then just use it for just

function and then just use it for just basic stuff and if you are not reusing

basic stuff and if you are not reusing your code much. So in that scenario you

your code much. So in that scenario you can simply create a lambda function.

can simply create a lambda function. Okay. So what that function will do that

Okay. So what that function will do that function will not get actually stored.

function will not get actually stored. Okay, it will simply perform the

Okay, it will simply perform the operation and that's it. So you're not

operation and that's it. So you're not actually registering that function like

actually registering that function like you can register but you can simply

you can register but you can simply write the lambda function as well. I

write the lambda function as well. I know it doesn't make any sense to talk

know it doesn't make any sense to talk like this. Let me just show you. So

like this. Let me just show you. So let's say you want to create function

let's say you want to create function called addition but this time you want

called addition but this time you want to use

to use lambda. Okay, what it will do? This is

lambda. Okay, what it will do? This is the function name. This is the function

the function name. This is the function that is lambda. Like that is you can say

that is lambda. Like that is you can say kind of structure syntax that we need to

kind of structure syntax that we need to follow lambda. Then we need to define

follow lambda. Then we need to define the parameter. Parameter is let's say x

the parameter. Parameter is let's say x or y. Two parameters. Okay. Then we add

or y. Two parameters. Okay. Then we add colon. Then what we need to return? We

colon. Then what we need to return? We need to return x + y. That's it. So this

need to return x + y. That's it. So this whole thing this whole thing is replaced

whole thing this whole thing is replaced with this. You do not need to write any

with this. You do not need to write any syntax. You need do not need to write

syntax. You need do not need to write any perform any indentation. No, just

any perform any indentation. No, just one line. Just one line. Let me just

one line. Just one line. Let me just uncomment it so you so that you can see.

uncomment it so you so that you can see. So this code is equivalent to this

So this code is equivalent to this one. Make sense? Addition addition you

one. Make sense? Addition addition you do not need to write df equals to

do not need to write df equals to instead of def you will write lambda.

instead of def you will write lambda. These are the parameters here and this

These are the parameters here and this is a returning value. That's it. That's

is a returning value. That's it. That's it. Now you can even use it same way.

it. Now you can even use it same way. You can simply say addition

You can simply say addition um we already have the calling

um we already have the calling statement. I will simply copy it from

here and let me uncomment it. Let's run this. You will simply get 30 perfect

this. You will simply get 30 perfect using this lambda function. So if you

using this lambda function. So if you are using something lightweight like

are using something lightweight like this, it makes sense to use just like

this, it makes sense to use just like one line of code. Okay, if you are doing

one line of code. Okay, if you are doing something heavy complex logic then

something heavy complex logic then obviously go with this traditional

obviously go with this traditional function. Okay, this is just for like

function. Okay, this is just for like lightweight functions. Make sense? So

lightweight functions. Make sense? So these are your functions. Now let's see

these are your functions. Now let's see what do we have in combination with

what do we have in combination with these functions. We have three popular

these functions. We have three popular kinds of operations that we perform with

kinds of operations that we perform with function. One is map, second is filter,

function. One is map, second is filter, third is reduce. Map, filter and reduce.

third is reduce. Map, filter and reduce. Let's uncover those topics. What are

Let's uncover those topics. What are map, filter and reduce? What are these

map, filter and reduce? What are these things? So basically these are the

things? So basically these are the functions or you can say these are the

functions or you can say these are the special you can say capabilities that we

special you can say capabilities that we get within Python. So what it what it

get within Python. So what it what it does? Let's say you created your

does? Let's say you created your function using DF or let's say lambda.

function using DF or let's say lambda. The choice is yours. Now you want to

The choice is yours. Now you want to perform that part. So let's say your

perform that part. So let's say your function is like relying on

function is like relying on just few parameters or you can say

just few parameters or you can say independent par parameters but you want

independent par parameters but you want to just perform that particular function

to just perform that particular function on an iterable. Let's say you have a

on an iterable. Let's say you have a list 1 2 3 4 5. You want to perform this

list 1 2 3 4 5. You want to perform this function on top of this list. That means

function on top of this list. That means on each element of the list. Let's say 1

on each element of the list. Let's say 1 2 3 4 5 and then you want to just create

2 3 4 5 and then you want to just create a new list based on

a new list based on this. Make sense? One one possible

this. Make sense? One one possible scenario can be is list comprehension

scenario can be is list comprehension that we can simply apply that logic

that we can simply apply that logic again and again. But if you have a

again and again. But if you have a function you can reuse that logic right

function you can reuse that logic right we can reuse that logic. Now you will

we can reuse that logic. Now you will simply say hey um why do we need to use

simply say hey um why do we need to use map filter reduce? We can simply create

map filter reduce? We can simply create a function for a list. Right. Exactly.

a function for a list. Right. Exactly. We can we can we can simply create a

We can we can we can simply create a function which will take a list. We can

function which will take a list. We can but the thing

but the thing is by that way we cannot handle the

is by that way we cannot handle the operation or you can say logic of

operation or you can say logic of function for individual values or a

function for individual values or a list. We have to create separate

list. We have to create separate functions. But by using map filter and

functions. But by using map filter and reduce we can actually apply the

reduce we can actually apply the functions that are handling the

functions that are handling the individual values and we can actually um

individual values and we can actually um perform that particular function on each

perform that particular function on each item of the iterable. Let's say this is

item of the iterable. Let's say this is a list which is the most common iterable

a list which is the most common iterable for data

for data engineers. Make sense? Let me show you

engineers. Make sense? Let me show you with the help of code and let's try to

with the help of code and let's try to first of all understand map. Okay let's

first of all understand map. Okay let's see. So let's say you have a list. You

see. So let's say you have a list. You have a list called my list. 1 2 3 4

have a list called my list. 1 2 3 4 5. Okay. Now you want to perform a

5. Okay. Now you want to perform a square of each

square of each particular number within this. Okay. If

particular number within this. Okay. If you just rewrite the code using

you just rewrite the code using function, you will simply say def. Okay.

function, you will simply say def. Okay. Let's say my

Let's say my function or you can say

square. Okay. Now you will simply take the parameter x okay and you will simply

the parameter x okay and you will simply say

say return return

return return um let's say because you know that this

um let's say because you know that this is a list so you will simply

is a list so you will simply perform list like this so you will

perform list like this so you will simply take the list and you can simply

simply take the list and you can simply create your own list let's say return

create your own list let's say return list okay return list and you are simply

list okay return list and you are simply saying that for

saying that for inpx

inpx return i istic

return i istic I make sense. Okay. And then you will

I make sense. Okay. And then you will simply say

print return list. Make sense? Now this function will help you not to

Now this function will help you not to write this code again and again. This

write this code again and again. This particular comprehension you can simply

particular comprehension you can simply save it in the function. Okay. Then you

save it in the function. Okay. Then you will simply say

will simply say um you will call this function my list.

um you will call this function my list. Okay. And then you will simply pass the

Okay. And then you will simply pass the list. Let's say my

list. Let's say my list. And that's it. Let's see the

list. And that's it. Let's see the output. Uh error list is not callable.

output. Uh error list is not callable. Wait, let me see what's

Wait, let me see what's wrong. Oh, this is square,

wrong. Oh, this is square, bro. So, uh real list is not defined.

bro. So, uh real list is not defined. So, this is the function square. This is

So, this is the function square. This is my

my list. Red

list. Red list. Oh, typo.

list. Oh, typo. Perfect. So it returned this 1 4 9 16

Perfect. So it returned this 1 4 9 16 25. Makes sense. But we have created

25. Makes sense. But we have created this function which is just accepting

this function which is just accepting list. What if I want to create a

list. What if I want to create a function which is called def

function which is called def squared def square that will take the

squared def square that will take the individual number and it will simply

individual number and it will simply return x uh

return x uh px let's say px into px

px let's say px into px basically square of

basically square of it

simple make sense So you want to create this function. What is the advantage of

this function. What is the advantage of this function? Because this way you can

this function? Because this way you can even pass an individual number and you

even pass an individual number and you can even pass a list. We cannot even

can even pass a list. We cannot even pass a list. You can using map method.

pass a list. You can using map method. So what we going to do? We will simply

So what we going to do? We will simply create this function and it is running

create this function and it is running fine. Code execution successful. Very

fine. Code execution successful. Very good. So now what we will do? We will

good. So now what we will do? We will simply say that

simply say that map. Okay. We simply need to write map

map. Okay. We simply need to write map and then the function. Function is

and then the function. Function is square. Square spelling is right. S Q U

square. Square spelling is right. S Q U A R E. Yep. Square. Then you need to

A R E. Yep. Square. Then you need to pass the iterable. Itable is my

pass the iterable. Itable is my list. Oh, okay. Simple. And I will

list. Oh, okay. Simple. And I will simply create a variable on top of it

simply create a variable on top of it called result. And I will just show you.

called result. And I will just show you. Obviously, nothing will be in the output

Obviously, nothing will be in the output because I know that this is actually

because I know that this is actually what this is doing. This is simply

what this is doing. This is simply mapping this function to each item of

mapping this function to each item of this particular list. And what it is

this particular list. And what it is doing? It is simply returning px into

doing? It is simply returning px into px. Now we need to store this result of

px. Now we need to store this result of each item into a list. That's why we'll

each item into a list. That's why we'll simply say

simply say list. We'll simply convert this output

list. We'll simply convert this output into a list. And

into a list. And that's you can just do right now. print

that's you can just do right now. print result and you should see it here.

result and you should see it here. Perfect. 1 4 9 1625. Very good. If you

Perfect. 1 4 9 1625. Very good. If you do not do this, if you do not do this,

do not do this, if you do not do this, you will actually see just map object.

you will actually see just map object. That means it is actually mapping this

That means it is actually mapping this function to each item 1 2 3 4 5 UR. But

function to each item 1 2 3 4 5 UR. But you need to convert that mapped object

you need to convert that mapped object into a specific kind of data structure.

into a specific kind of data structure. It can be either tpple. It can be uh

It can be either tpple. It can be uh either you can say list. So if you just

either you can say list. So if you just write in a

tpple and then if you just run it, you should see a tpple. If you just want to

should see a tpple. If you just want to convert it into a list, you can just

convert it into a list, you can just write list. Most probably you will just

write list. Most probably you will just convert it into a list. That's the whole

convert it into a list. That's the whole point of creating this function and

point of creating this function and taking just only one value instead of a

taking just only one value instead of a list. Then map this function to iterate

list. Then map this function to iterate it through each item of this particular

it through each item of this particular list. That's the whole concept of map.

list. That's the whole concept of map. Okay. Now what is the filter? What is

Okay. Now what is the filter? What is filter? Let's say in your particular

filter? Let's say in your particular code you are only returning this value

code you are only returning this value if

if uh

uh px mod

px mod 2 equals to equals to zero that

means if this number is even only then you are returning it. So basically you

you are returning it. So basically you are taking a number and then what you

are taking a number and then what you are doing you are simply returning only

are doing you are simply returning only and only if that particular condition is

and only if that particular condition is met. So in that scenario you use

met. So in that scenario you use something called as filter. Why? Let's

something called as filter. Why? Let's let's not use filter. Let's see what

let's not use filter. Let's see what will happen here. Okay. So it will

will happen here. Okay. So it will simply say none because this condition

simply say none because this condition is not met. Then four then none then 16

is not met. Then four then none then 16 then none.

then none. Filter helps us to remove those none

Filter helps us to remove those none none none none none. It will simply

none none none none. It will simply first of all it will do exactly the same

first of all it will do exactly the same stuff that map is doing. It will simply

stuff that map is doing. It will simply apply the filter or not filter like

apply the filter or not filter like apply the function on each item 1 2 3 4

apply the function on each item 1 2 3 4 5 check it and it will return only and

5 check it and it will return only and only if condition is met. Okay, that's

only if condition is met. Okay, that's the uh you can say use of map, right? It

the uh you can say use of map, right? It will simply apply it and if yes it will

will simply apply it and if yes it will get the result and it will just convert

get the result and it will just convert it into a list. But we are seeing none

it into a list. But we are seeing none none none that we should not see. That

none none that we should not see. That means we need to filter our list. Then

means we need to filter our list. Then we can simply use

we can simply use filter. When we use

filter. When we use filter it will not return none. It will

filter it will not return none. It will simply return two and four. That's it.

simply return two and four. That's it. Make sense? Uh I do not use filter much.

Make sense? Uh I do not use filter much. Okay. I just use map. Um sometimes I use

Okay. I just use map. Um sometimes I use filter but not very often. Yeah. Yeah.

filter but not very often. Yeah. Yeah. Yeah. Yeah. So two things are covered.

Yeah. Yeah. So two things are covered. Now what is this reduce? Now what is

Now what is this reduce? Now what is this reduce? Let's

this reduce? Let's say let's say in this your list. Okay

say let's say in this your list. Okay you are taking let's say two variables

you are taking let's say two variables like two two parameters px and py and

like two two parameters px and py and you are actually

you are actually returning px +

returning px + py. Okay. So you are actually turning

py. Okay. So you are actually turning this. Okay, let me perform this. Okay,

this. Okay, let me perform this. Okay, and let's first of all try with map so

and let's first of all try with map so that you can actually see. So let's try

that you can actually see. So let's try it with map. So what it will do? Error.

it with map. So what it will do? Error. Why? Because it needs to apply this

Why? Because it needs to apply this function. Okay, this square function on

function. Okay, this square function on top of this each item. Map performs the

top of this each item. Map performs the like uh runs the function on each item.

like uh runs the function on each item. Filter runs the function on each item

Filter runs the function on each item but reduce works something different.

but reduce works something different. What reduce will

What reduce will do? Reduce will first take the first two

do? Reduce will first take the first two elements of your list. It will simply

elements of your list. It will simply apply that particular function on those

apply that particular function on those two elements. Make sense? It will become

two elements. Make sense? It will become three. 1 + 2 equals to three. So it

three. 1 + 2 equals to three. So it reduce the list. Then it will say 3 + 3

reduce the list. Then it will say 3 + 3 it will become 6. Then it will say 6 + 4

it will become 6. Then it will say 6 + 4 it becomes 10. Then 10 + 5 it becomes

it becomes 10. Then 10 + 5 it becomes five. So it will keep on reducing the

five. So it will keep on reducing the list. Let me run this and you will see

list. Let me run this and you will see error. Wow. Reduce is not defined. Wait

error. Wow. Reduce is not defined. Wait wait wait wait. List and reduce. Oh

wait wait wait. List and reduce. Oh obviously because this is not a list. So

obviously because this is not a list. So let me run this. Error. Wait wait wait

let me run this. Error. Wait wait wait wait. Result equals

wait. Result equals reduce. I think there's a typo. Hold on.

reduce. I think there's a typo. Hold on. I think we first need to import this

I think we first need to import this function. I'm not sure. Let me just see

function. I'm not sure. Let me just see from funk tools. import

uh reduce. Let's see if it works. Yeah, it works. So, basically

works. Yeah, it works. So, basically this is not a built-in function. We need

this is not a built-in function. We need to import it. So, that's why map and

to import it. So, that's why map and your filter both are like inbuilt. But

your filter both are like inbuilt. But yeah for for reduce you need to just

yeah for for reduce you need to just reduce uh not reduce like pull it from

reduce uh not reduce like pull it from funk tools. Make sense? Make sense?

funk tools. Make sense? Make sense? Makes sense. Makes sense. So this is

Makes sense. Makes sense. So this is your reduce function. Reduce is a

your reduce function. Reduce is a function that I have used like so so so

function that I have used like so so so rarely. I do not like use reduce

rarely. I do not like use reduce function. But yeah map function is your

function. But yeah map function is your go-to function when you have an iterable

go-to function when you have an iterable when you just want to perform your

when you just want to perform your function on each item of the um you can

function on each item of the um you can say list. Your go-to function. Filter I

say list. Your go-to function. Filter I sometimes use because in most of the

sometimes use because in most of the cases I simply need to apply my function

cases I simply need to apply my function on each element of the list. Map is your

on each element of the list. Map is your function. Map you should just master

function. Map you should just master map. Filter is fine. Reduce is like very

map. Filter is fine. Reduce is like very rare scenario but you should know about

rare scenario but you should know about this. You should know because in some

this. You should know because in some scenarios you can just tackle with some

scenarios you can just tackle with some use cases where you need to use reduce.

use cases where you need to use reduce. Okay. So this is all about your

Okay. So this is all about your functions and using those special forces

functions and using those special forces of Python map filter and reduce. Make

of Python map filter and reduce. Make sense? Makes sense. Makes sense. Make

sense? Makes sense. Makes sense. Make sense. Make some noise in the comments

sense. Make some noise in the comments right now if you liked it. Let me see

right now if you liked it. Let me see what do I have more in the checklist.

what do I have more in the checklist. Okay. Done.

Okay. Done. Done. Files we are not covering because

Done. Files we are not covering because it's fine because it's not very much

it's fine because it's not very much important from data engineing point of

important from data engineing point of view. Uh then functions are already

view. Uh then functions are already done. Oh, let's cover this. Let's cover

done. Oh, let's cover this. Let's cover this.

this. So, copy list. Uh this is fine.

Okay, basically before like recording this video, I was literally planning

this video, I was literally planning like what I need to cover and what I not

like what I need to cover and what I not need to cover because there's like so

need to cover because there's like so many things. Now let's talk about

many things. Now let's talk about exceptional handling in Python and this

exceptional handling in Python and this is

is your non-negotiable because whenever

your non-negotiable because whenever you're writing your code let's say in

you're writing your code let's say in pispark anything you have to handle

pispark anything you have to handle exceptions okay or you can say you can

exceptions okay or you can say you can you have to handle those things. So it

you have to handle those things. So it is very much popular in other

is very much popular in other programming languages called try catch

programming languages called try catch method but in Python we call it as try

method but in Python we call it as try except method not try catch method and I

except method not try catch method and I also call it as like try accept method.

also call it as like try accept method. So basically what why do we need try

So basically what why do we need try except or basically what is like try

except or basically what is like try except method. It's very handy. Let me

except method. It's very handy. Let me just tell you what's that. So let's talk

just tell you what's that. So let's talk about exception handling. What is

about exception handling. What is exception handling? Let's say you are

exception handling? Let's say you are writing your code. Okay let's say this

writing your code. Okay let's say this is you and you are writing your code.

is you and you are writing your code. You are a pro developers and you do not

You are a pro developers and you do not get any errors in your code. You are a

get any errors in your code. You are a pro pro developer. Okay, let's say this

pro pro developer. Okay, let's say this is your code. This is one block of code.

is your code. This is one block of code. There's a second block of code. This is

There's a second block of code. This is third block of code and so on. Okay, but

third block of code and so on. Okay, but let's say by chance by chance I know

let's say by chance by chance I know this cannot happen with you, right? But

this cannot happen with you, right? But by chance this block of code actually

by chance this block of code actually failed. Oh, okay. By by chance. Okay. So

failed. Oh, okay. By by chance. Okay. So in that particular scenario, rest of the

in that particular scenario, rest of the blocks will not be running because it

blocks will not be running because it faced an error. But you want to avoid

faced an error. But you want to avoid it. Okay, you may just need to receive

it. Okay, you may just need to receive the logs regarding that error and you

the logs regarding that error and you just need to just continue with the rest

just need to just continue with the rest of the code. It can be your use case as

of the code. It can be your use case as well. So in that particular scenario you

well. So in that particular scenario you need to handle exceptions you need to

need to handle exceptions you need to handle errors and we use something

handle errors and we use something called as try except method which is

called as try except method which is similar to try catch

similar to try catch method. Make sense? I know not 100% but

method. Make sense? I know not 100% but once I show you in the code it will make

once I show you in the code it will make sense. Let me just show you. So let's

sense. Let me just show you. So let's say you are writing your code something

say you are writing your code something like this. Um let's say x= 10. Okay.

like this. Um let's say x= 10. Okay. If x greater than

If x greater than 10 then you simply need to

10 then you simply need to print greater than

print greater than 10. Okay? Otherwise you need to simply

say print blah

blah. Okay. You need to simply do this. When you just run this, it will work

When you just run this, it will work fine. Right? Let's

fine. Right? Let's say I did something like

say I did something like this. I will see the error. Ooh. And

this. I will see the error. Ooh. And rest of the code, let's say I have

rest of the code, let's say I have this. Let's say I have this hello

this. Let's say I have this hello world. This will not run. Why? Because

world. This will not run. Why? Because it will stop here. And it is saying,

it will stop here. And it is saying, hey, this is a string. How you can just

hey, this is a string. How you can just compare the string with arithmetic

compare the string with arithmetic operation? see string and 10 and this

operation? see string and 10 and this code is not working. I want to do

code is not working. I want to do something in my code so that okay even

something in my code so that okay even if I get the error it's fine it should

if I get the error it's fine it should just tell me what is the issue that's it

just tell me what is the issue that's it should not block my code to execute rest

should not block my code to execute rest of the code okay so for that what I will

of the code okay so for that what I will do I will

do I will simply use try and then I will simply

simply use try and then I will simply write my logic okay this is my logic

write my logic okay this is my logic this is try so what it will do it will

this is try so what it will do it will try to run this if it throws an error in

try to run this if it throws an error in this particular code

this particular code block then it will jump to the next

block then it will jump to the next thing which is

thing which is accept which is accept and whatever I

accept which is accept and whatever I write this in this let's say I want to

write this in this let's say I want to say hey you have an

say hey you have an error and that's it will not block this

error and that's it will not block this code it will simply check this if it is

code it will simply check this if it is running fine okay it will skip this it

running fine okay it will skip this it will directly run this If it throws an

will directly run this If it throws an error then it will run this one and it

error then it will run this one and it will run this one as well. Let's run

will run this one as well. Let's run this and let's see. See this time it

this and let's see. See this time it didn't fail. He said hey you have an

didn't fail. He said hey you have an error and then it ran rest of the

error and then it ran rest of the code.

code. Oh this is really

Oh this is really nice. There is an advanced version of

nice. There is an advanced version of this. Let's say you do not need to write

this. Let's say you do not need to write print. You simply need to write the

print. You simply need to write the error. Like what is the error? You can

error. Like what is the error? You can simply say except

simply say except exception as E. Basically E is the error

exception as E. Basically E is the error and we are using exception method. Okay,

and we are using exception method. Okay, you will simply say E. And now this time

you will simply say E. And now this time you will see the error as well. Greater

you will see the error as well. Greater than not supported between instances of

than not supported between instances of string and end. Wow. You can even save

string and end. Wow. You can even save this as your log so that you can check

this as your log so that you can check hey what's wrong.

hey what's wrong. This is the way to handle errors or you

This is the way to handle errors or you can say error handling or exception

can say error handling or exception handling. Make sense? Make sense? Makes

handling. Make sense? Make sense? Makes sense. Makes sense. Now let me introduce

sense. Makes sense. Now let me introduce you to the frings because now this is

you to the frings because now this is the best time and you have the real

the best time and you have the real world example in front of you. First of

world example in front of you. First of all, what are frings? Basically, I will

all, what are frings? Basically, I will simply comment it out and I will just

simply comment it out and I will just show you what are franks. So this is a

show you what are franks. So this is a special kind of string that we use. So

special kind of string that we use. So let's say you have something like this

let's say you have something like this my string

my string equals hello my name is an this is fine

equals hello my name is an this is fine this will simply say print my

this will simply say print my string

string okay this is fine what if I want to

okay this is fine what if I want to create a variable let's say name

create a variable let's say name variable and I want to store that

variable and I want to store that information in this and every time I

information in this and every time I want to use this

want to use this variable. This

variable. This variable within this particular

variable within this particular statement. Let's make it more dynamic.

statement. Let's make it more dynamic. How are

How are you? Make sense? Now I want to print

you? Make sense? Now I want to print this

this name at this

name at this location by using this variable. How we

location by using this variable. How we can do that? This is where fringing

can do that? This is where fringing comes handy. So what you can do here?

comes handy. So what you can do here? You can simply

You can simply say f in the beginning of the string.

say f in the beginning of the string. Okay. Then what you will do? You will

Okay. Then what you will do? You will simply put the variable name in the

simply put the variable name in the curly braces. I will simply say name and

curly braces. I will simply say name and then curly braces close. Let me just

then curly braces close. Let me just show you the magic.

show you the magic. See hello my name is an how are you? If

See hello my name is an how are you? If I just change the name let's say

love. Hello my name is love. How are you? See that's how it works. You can

you? See that's how it works. You can actually combine variables and string

actually combine variables and string within the

within the string. And why this is handy? Let's say

string. And why this is handy? Let's say this is your realtime scenario. And here

this is your realtime scenario. And here you just want to say

you just want to say print

print hey first of all f then

hey first of all f then hey that's your error or let's say you

hey that's your error or let's say you got this

got this error and then you are

error and then you are simply saving this in the variable make

simply saving this in the variable make sense very good now all good let's run

sense very good now all good let's run And you will see hey you got this error

And you will see hey you got this error then you have the error and then hello

then you have the error and then hello world make sense. So this is a variable

world make sense. So this is a variable e see this is a

e see this is a variable franks remember this and now

variable franks remember this and now you know error handling very well and in

you know error handling very well and in the try except method we have something

the try except method we have something called as finally as well. Now what is

called as finally as well. Now what is this finally? So this I just highlighted

this finally? So this I just highlighted this thing finally because this is

this thing finally because this is really really important. So let's say

really really important. So let's say you are building a solution like

you are building a solution like this. We know that we know that if my

this. We know that we know that if my this logic is correct, this will not

this logic is correct, this will not run. Makes sense because this is right.

run. Makes sense because this is right. If my this logic fails, this logic will

If my this logic fails, this logic will run. Makes

run. Makes sense. We have a third member of this

sense. We have a third member of this group which is called finally.

group which is called finally. Whatever you write within the finally,

Whatever you write within the finally, it will execute no matter if you get the

it will execute no matter if you get the error or not. Let me just show you. I

error or not. Let me just show you. I will simply say I will always run. I

will simply say I will always run. I will always run. So let's say you have

will always run. So let's say you have the error. Let's see what will happen.

the error. Let's see what will happen. It will simply say, hey, you have the

It will simply say, hey, you have the error. I will always run and hello

error. I will always run and hello world. That means this block ran after

world. That means this block ran after this one.

this one. Okay. Okay. Sorry, this one. This block

Okay. Okay. Sorry, this one. This block ran after this one. Make sense? If my

ran after this one. Make sense? If my value is correct, then also it will run.

value is correct, then also it will run. It will simply say blah blah. I will

It will simply say blah blah. I will always run hello world. What's the use

always run hello world. What's the use case of it? What's the use case of it?

case of it? What's the use case of it? It makes sure that your code is

It makes sure that your code is executing these stuff and it is working

executing these stuff and it is working fine and it is running this only and

fine and it is running this only and only after this or this only after try

only after this or this only after try or

or accept. Make sense? This is I know like

accept. Make sense? This is I know like will not be very much used but yeah you

will not be very much used but yeah you should know about this

and let me see what do we have. Oh this is really important. Okay

have. Oh this is really important. Okay let's talk about this. This is basically

let's talk about this. This is basically this will actually build a strong base

this will actually build a strong base of your understanding in functions. So

of your understanding in functions. So in functions I told you that it always

in functions I told you that it always it always returns only one time. It

it always returns only one time. It always returns only one time. It cannot

always returns only one time. It cannot return multiple values because once it

return multiple values because once it returns something it will take the exit.

returns something it will take the exit. Okay. Okay. Okay. Okay. Okay. So now

Okay. Okay. Okay. Okay. Okay. So now let's say let's build a function because

let's say let's build a function because I want to share this thing with you. I

I want to share this thing with you. I also like spent a lot of time when I was

also like spent a lot of time when I was just learning this. So what what

just learning this. So what what happened? Let's create a function. Okay.

happened? Let's create a function. Okay. Let's create a function. Let's create a

Let's create a function. Let's create a function like this. My function. And

function like this. My function. And this will actually clear a lot of things

this will actually clear a lot of things for you. Okay. Let's say this is a

for you. Okay. Let's say this is a simple function. And within this

simple function. And within this function you are applying try except

function you are applying try except method. Hm. Make sense? So you will

method. Hm. Make sense? So you will simply say or let's take an example.

simply say or let's take an example. Um let's let's let's just do like like

Um let's let's let's just do like like this as well. So I will simply say

this as well. So I will simply say uh parameter because it will be easier

uh parameter because it will be easier for you just to use it px otherwise you

for you just to use it px otherwise you would need to use input function and

would need to use input function and all. So px. So this is my function.

all. So px. So this is my function. Okay. So now what will happen? I will

Okay. So now what will happen? I will simply say

simply say try and I will simply write my logic

try and I will simply write my logic if let's say

if let's say px okay mod

px okay mod 2 let's say I'm checking if it is even

2 let's say I'm checking if it is even or not okay equals to equal to0 then

or not okay equals to equal to0 then return 1 that means true else

return 1 that means true else uh you can simply

uh you can simply say zero

say zero else or I'm just checking for if I'm not

else or I'm just checking for if I'm not even checking for anything. Okay. If it

even checking for anything. Okay. If it is even, then only return one.

is even, then only return one. Otherwise, do not do anything. And at

Otherwise, do not do anything. And at the same time, if I have any errors, I

the same time, if I have any errors, I will simply say

will simply say except and return

error. Make sense? Error. Same same stuff. Or let's

sense? Error. Same same stuff. Or let's say except

say except exception as E. Okay. Or return E. Make

exception as E. Okay. Or return E. Make sense? Very good. So then I will simply

sense? Very good. So then I will simply say

say finally.

finally. If let's let's take an example without

If let's let's take an example without finally. If I write

finally. If I write print hello world, will it work? Will it

print hello world, will it work? Will it work? Let me show you. First of all,

work? Let me show you. First of all, let's execute this code and let's call

let's execute this code and let's call this function. My

this function. My function. Let's say I'm giving four.

function. Let's say I'm giving four. Four is an even number. So it will

Four is an even number. So it will simply

simply say one, right? Let's run this. Wow.

say one, right? Let's run this. Wow. This is it. It simply completed this and

This is it. It simply completed this and it returned one. Okay. And we know that

it returned one. Okay. And we know that it is saved in this particular function.

it is saved in this particular function. It didn't go here because it didn't

It didn't go here because it didn't throw any error. But why this command

throw any error. But why this command didn't run? Because we got return

didn't run? Because we got return function. Return function like return

function. Return function like return command. The moment we see return

command. The moment we see return command or you can say Python sees the

command or you can say Python sees the return command, it will simply take the

return command, it will simply take the exit from that function. it will not

exit from that function. it will not even go on the below quotes. But if we

even go on the below quotes. But if we write print hello world

write print hello world before before it will work. See hello

before before it will work. See hello world it will work. But if I write print

world it will work. But if I write print hello world after this print hello world

hello world after this print hello world will not be executed. Why? Because this

will not be executed. Why? Because this will not even go beyond this because

will not even go beyond this because this is

this is strictly pausing it.

strictly pausing it. It will simply say hey take exit just go

It will simply say hey take exit just go away. But if we just want to simply

away. But if we just want to simply print something after the execution even

print something after the execution even if we get the return value this is where

if we get the return value this is where your finally keyword comes handy. I will

your finally keyword comes handy. I will simply say

simply say finally. Okay. And I will simply write

finally. Okay. And I will simply write this. Now I will see hello world two

this. Now I will see hello world two times. Perfect. One is obviously at the

times. Perfect. One is obviously at the beginning which is the respective of try

beginning which is the respective of try accept method. But after having the

accept method. But after having the return value still I'm having print.

return value still I'm having print. Why? Because this command will always

Why? Because this command will always run. Always run. This is true for

run. Always run. This is true for functions as well. Can you imagine? This

functions as well. Can you imagine? This is true for functions as

is true for functions as well.

well. H okay this makes sense. So this is like

H okay this makes sense. So this is like one thing that you need to master for

one thing that you need to master for functions. Let me just share the other

functions. Let me just share the other one as well which is called global

one as well which is called global variables. Okay let's talk about global

variables. Okay let's talk about global variables in function. So let's say you

variables in function. So let's say you have a variable called x= to 10. This is

have a variable called x= to 10. This is very popular man. X= let's say 100 X

very popular man. X= let's say 100 X equals to 100 if and you do not even

equals to 100 if and you do not even have any parameter okay this is a simple

have any parameter okay this is a simple function let's say you want to print X

function let's say you want to print X can you do

can you do that can you do that let me just run

that can you do that let me just run this obviously 100

this obviously 100 why because it is taking the global

why because it is taking the global variable here which is outside of this

variable here which is outside of this function okay what if I define something

function okay what if I define something called as this x= to 5 inside the

called as this x= to 5 inside the function what I will get obviously five

function what I will get obviously five because this time it will give the

because this time it will give the priority to its own x value instead of

priority to its own x value instead of global value of x instead of global

global value of x instead of global value of

x okay but if I want to use or print global value can I just do something

global value can I just do something like

like this no we cannot say global here in a

this no we cannot say global here in a print command. Okay, makes sense. Can I

print command. Okay, makes sense. Can I do something like this? Let's say this

do something like this? Let's say this is x= to 5. Then I say global

is x= to 5. Then I say global x. No. Name x is

x. No. Name x is assigned to before global

assigned to before global declaration. That means it already

declaration. That means it already defined x. Now you cannot do this. But

defined x. Now you cannot do this. But if you define it before x, you can

if you define it before x, you can perform

perform this. Why? because it first took the

this. Why? because it first took the value of x. Okay, then it override that

value of x. Okay, then it override that value with five and then it printed that

value with five and then it printed that value. Okay, even if I do not write

value. Okay, even if I do not write this, I will still get 100 because I am

this, I will still get 100 because I am getting the global variable and this is

getting the global variable and this is by default there. Even if you do not

by default there. Even if you do not write global word, it will simply by

write global word, it will simply by default take this value of x. But if you

default take this value of x. But if you have defined something with the same

have defined something with the same variable name inside your function, it

variable name inside your function, it will take the priority. That's the whole

will take the priority. That's the whole point of discussion right now. Make

point of discussion right now. Make sense? That's the difference between

sense? That's the difference between global and local variable. Local

global and local variable. Local variable always takes the priority if

variable always takes the priority if you are just defining it within the

you are just defining it within the function. Make sense? Make sense? Make

function. Make sense? Make sense? Make sense? Now let's see if anything is left

sense? Now let's see if anything is left with this topic because I want to cover

with this topic because I want to cover all the things. Oh, there's one more

all the things. Oh, there's one more thing. I think I just I I remember I

thing. I think I just I I remember I noted down. Um I think there was

noted down. Um I think there was something a little error. I just Yeah,

something a little error. I just Yeah, perfect. I I knew it because this was my

perfect. I I knew it because this was my favorite topic at that time as well. So

favorite topic at that time as well. So basically, let's say you are writing

basically, let's say you are writing your code. Okay, you are writing your

your code. Okay, you are writing your code. You are writing your code and you

code. You are writing your code and you got the value x= 100. You need to apply

got the value x= 100. You need to apply if condition. If x less than 100 you

if condition. If x less than 100 you need to throw an error even if you do

need to throw an error even if you do not have an error. What? What? Yes, you

not have an error. What? What? Yes, you need to build or you can say create your

need to build or you can say create your custom error. That's called user error.

custom error. That's called user error. From here you will do something like

From here you will do something like this.

this. Raise value

Raise value error. Something like this. I'm just

error. Something like this. I'm just explaining you stop. Okay. Raise value

explaining you stop. Okay. Raise value error. Obviously it will not work

error. Obviously it will not work because there's a syntax for it. You

because there's a syntax for it. You need to raise something called as value

need to raise something called as value error because you want to say hey

error because you want to say hey there's something called as like value

there's something called as like value error something like this. You can even

error something like this. You can even raise the value errors or you can say

raise the value errors or you can say errors on your own because your program

errors on your own because your program is designed in such a way that that

is designed in such a way that that cannot take value less than 100 cannot.

cannot take value less than 100 cannot. So in that scenario you have to raise

So in that scenario you have to raise custom

custom errors. Make sense? This is very popular

errors. Make sense? This is very popular by the way. So in order to do this what

by the way. So in order to do this what you can do you can simply type value

you can do you can simply type value error and just make your own error.

error and just make your own error. Let's say um value less than 100 is not

Let's say um value less than 100 is not allowed. This is your own error. Okay.

allowed. This is your own error. Okay. So you will see the error but context

So you will see the error but context will be this whatever you will write

will be this whatever you will write here. Okay. Let's run this. Okay. This

here. Okay. Let's run this. Okay. This is successful because x is not less than

is successful because x is not less than 100. Let's say 99. So this will throw an

100. Let's say 99. So this will throw an error that value less than 100 is not

error that value less than 100 is not allowed. This is a value error because

allowed. This is a value error because this is a kind of value because this is

this is a kind of value because this is something related to value error, right?

something related to value error, right? There are so many errors. You can even

There are so many errors. You can even Google

Google uh

uh raise error in Python. There are so

raise error in Python. There are so many raise error in Python. Python raise

many raise error in Python. Python raise an

an exception. So you can say raise

exception. So you can say raise exception. You can even raise exception.

exception. You can even raise exception. Sorry no numbers below zero. So this is

Sorry no numbers below zero. So this is so similar, right? So this will simply

so similar, right? So this will simply throw an exception. What is the

throw an exception. What is the difference between like exception value

difference between like exception value error? So the difference is here when

error? So the difference is here when you will be just seeing the type of

you will be just seeing the type of error, you will see it value error. If I

error, you will see it value error. If I write

write exception, you will see the exception

exception, you will see the exception error. See exception error. So it's up

error. See exception error. So it's up to you. You can just pick any error as

to you. You can just pick any error as per your obviously convenience. There is

per your obviously convenience. There is a type error as well like maybe someone

a type error as well like maybe someone just did a typo. So you can simply say

just did a typo. So you can simply say raise type error. So it will simply show

raise type error. So it will simply show them that this is a kind of error and

them that this is a kind of error and this is the error value. So that means

this is the error value. So that means this is not actually an error in Python

this is not actually an error in Python world but this is an error for your

world but this is an error for your program. So that means you forcefully

program. So that means you forcefully want to throw an error. That's where you

want to throw an error. That's where you use your like raise error. Okay, make

use your like raise error. Okay, make sense? Very good. Very good. Very good.

sense? Very good. Very good. Very good. Very good. I hope now it is pretty much

Very good. I hope now it is pretty much clear to you like what are the things

clear to you like what are the things and I think I have covered all the

and I think I have covered all the things that I wanted to cover. One thing

things that I wanted to cover. One thing is left and I want to cover that because

is left and I want to cover that because that is really important. Okay, like

that is really important. Okay, like these are like small small things

these are like small small things because Python is so so so wide. So

because Python is so so so wide. So let's cover that as well. What is that?

let's cover that as well. What is that? Basically let me clear everything. We

Basically let me clear everything. We going to learn something about enumerate

going to learn something about enumerate function. Enumerate function. What is

function. Enumerate function. What is enumerate function? So let's say you

enumerate function? So let's say you have a list called my list equals 1 2 or

have a list called my list equals 1 2 or let's say

let's say 100 200 300 400 500. Now you want to run

100 200 300 400 500. Now you want to run a loop for I in my list. Okay, you need

a loop for I in my list. Okay, you need to simply say print I. You will say

to simply say print I. You will say Anlama this is so simple. I know. Can

Anlama this is so simple. I know. Can you just print

you just print the position as well? Oh, whoa, whoa,

the position as well? Oh, whoa, whoa, whoa, wait, wait, wait, wait, wait. Can

whoa, wait, wait, wait, wait, wait. Can you repeat? Let's say you want to just

you repeat? Let's say you want to just simply print the value of the position.

simply print the value of the position. This is zero. This is one, this is two,

This is zero. This is one, this is two, this is three, this is four. This is

this is three, this is four. This is doable. This is not a big deal because

doable. This is not a big deal because we can simply run a loop for like length

we can simply run a loop for like length of this list and we can start the list

of this list and we can start the list from zero and we can simply get this.

from zero and we can simply get this. But let's say you want to do both. You

But let's say you want to do both. You want to get the position value as well

want to get the position value as well plus you want to get the list value as

plus you want to get the list value as well. Obviously it is also doable but we

well. Obviously it is also doable but we have a very powerful function for it.

have a very powerful function for it. It's called enumerate. I can write

It's called enumerate. I can write something like this

something like this enumerate. Okay. When I write enumerate

enumerate. Okay. When I write enumerate then I cannot run this because it will

then I cannot run this because it will simply throw an basically like okay it

simply throw an basically like okay it will work but it will not give me the

will work but it will not give me the desired result. So basically what

desired result. So basically what happens for this what it will do it will

happens for this what it will do it will simply store the tpple for each

simply store the tpple for each iteration 0 100 1 200 2 300 3 400 4 500

iteration 0 100 1 200 2 300 3 400 4 500 but in the real world how we use it I

but in the real world how we use it I will simply create two you can say

will simply create two you can say variables one is I second is let's say x

variables one is I second is let's say x i stands for the position x stand for

i stands for the position x stand for the value so I will simply say print i

the value so I will simply say print i if I just want position. If I want

if I just want position. If I want value, I can simply say X. So that's how

value, I can simply say X. So that's how we simply fetch the records. And

we simply fetch the records. And obviously in order to understand it, you

obviously in order to understand it, you can simply run print I just to see like

can simply run print I just to see like what it will hold. It will hold the

what it will hold. It will hold the position and the value itself. Enumerate

position and the value itself. Enumerate is very handy and you will see in your

is very handy and you will see in your real life as well. It is very

real life as well. It is very handy. Okay, makes sense. Makes sense.

handy. Okay, makes sense. Makes sense. Makes sense. Makes sense. Okay, now it's

Makes sense. Makes sense. Okay, now it's time to just unpack a gift for you.

time to just unpack a gift for you. What's that? You will feel really

What's that? You will feel really excited after knowing about this. Let me

excited after knowing about this. Let me just tell you what's

just tell you what's that. So now let's try to talk about oop

that. So now let's try to talk about oop that is objectoriented programming in

that is objectoriented programming in Python. And let me just tell you in

Python. And let me just tell you in every programming language oop is one of

every programming language oop is one of the hottest topics because whenever you

the hottest topics because whenever you are just scaling your program whenever

are just scaling your program whenever you're building a big

you're building a big application you cannot survive without

application you cannot survive without oop really or you can say your

oop really or you can say your application cannot survive without oop

application cannot survive without oop trust me the reason is let me just tell

trust me the reason is let me just tell you what is oop and before even

you what is oop and before even explaining oop I will just explain

explaining oop I will just explain through an example let's say you are

through an example let's say you are building an application for online store

building an application for online store you have so many functions you have

you have so many functions you have defined like so many functions because

defined like so many functions because obviously functions promote reusability

obviously functions promote reusability of code I would say even functions are

of code I would say even functions are not capable enough to structure your

not capable enough to structure your data let's say you have one function

data let's say you have one function okay the red set so red boxes are your

okay the red set so red boxes are your functions okay so let's say you have

functions okay so let's say you have this function this function this

this function this function this function this function this function

function this function this function this function this function this

this function this function this function this function this function

function this function this function this function this function this

this function this function this function this function

function this function this function. This function there are

this function. This function there are so many functions scattered in your

so many functions scattered in your program. Not just functions. Let's talk

program. Not just functions. Let's talk about variables. So many variables. So

about variables. So many variables. So many so many so many so many so many. So

many so many so many so many so many. So many

many variables. So many

variables. Now just try to scale this program. Forget about scaling, bro.

program. Forget about scaling, bro. Forget about scaling. Forget about

Forget about scaling. Forget about scaling. How does it looking? How does

scaling. How does it looking? How does it look like? How does it looking? How

it look like? How does it looking? How is it

is it looking? It's a mess. It's a mess. You

looking? It's a mess. It's a mess. You have so many functions. You have so many

have so many functions. You have so many variables. You do not even remember like

variables. You do not even remember like what function is for what purpose. Yes,

what function is for what purpose. Yes, you will provide very good naming

you will provide very good naming convention for all the functions. Still

convention for all the functions. Still you will not be able to handle that

you will not be able to handle that mess. You will not be able to handle

mess. You will not be able to handle that mess. So what we can do? Let's say

that mess. So what we can do? Let's say I figured out this function, this

I figured out this function, this function, this function, this function

function, this function, this function actually belong to a specific use case.

actually belong to a specific use case. If you are building an online

If you are building an online application for stores, let's say online

application for stores, let's say online retail store, this particular function,

retail store, this particular function, these particular functions are related

these particular functions are related to your customers are related to your

to your customers are related to your customers. So these four functions plus

customers. So these four functions plus these variables. So what you can do, you

these variables. So what you can do, you can actually create a

can actually create a bundle using these functions and using

bundle using these functions and using these variables and you can just

these variables and you can just organize these things together and you

organize these things together and you can actually create a template. You can

can actually create a template. You can actually create a bundle that you can

actually create a bundle that you can reuse it whenever you want. So that

reuse it whenever you want. So that means you can even reuse these

means you can even reuse these functions. You can even reuse this

functions. You can even reuse this variables plus with better

variables plus with better management better you can say uh

management better you can say uh scalability because it it it it will be

scalability because it it it it will be so easy for you to manage all these

so easy for you to manage all these things. So we just create bundles. Let's

things. So we just create bundles. Let's say this is bundle number one. Then you

say this is bundle number one. Then you simply created a next bundle for these

simply created a next bundle for these functions and all these variables belong

functions and all these variables belong to this. So this will be b bundle number

to this. So this will be b bundle number two. Let's say bundle number three. So

two. Let's say bundle number three. So this is our bundle number three. That's

this is our bundle number three. That's it. Now the whole mess is actually

it. Now the whole mess is actually grouped together to three bundles.

grouped together to three bundles. Bundle number one, which is this one.

Bundle number one, which is this one. Bundle number two, which is this one.

Bundle number two, which is this one. Bundle number three. Now let's say I

Bundle number three. Now let's say I want to add something in my customers

want to add something in my customers bundle. I can simply add a function in

bundle. I can simply add a function in this particular bundle. And I can simply

this particular bundle. And I can simply add a variable in this bundle. There's

add a variable in this bundle. There's no need to just find, hey, where's my

no need to just find, hey, where's my code? Where's this? Where's

code? Where's this? Where's that? So this is called

that? So this is called class. This is the concept of class

class. This is the concept of class where it combines your functions and it

where it combines your functions and it will be called as methods. Methods are

will be called as methods. Methods are your functions. But when it got

your functions. But when it got inherited, not inherited, we are not

inherited, not inherited, we are not talking about inheritance. Like normally

talking about inheritance. Like normally when it got embedded within the bundle,

when it got embedded within the bundle, it becomes methods.

it becomes methods. And these are your

And these are your variables. These are your

variables. These are your variables. So this is a concept of

variables. So this is a concept of class. Okay. Now we just talked about

class. Okay. Now we just talked about that we can even reuse these function

that we can even reuse these function and these

and these variables

variables using objects. So I can create object

using objects. So I can create object number one from this bundle. I can even

number one from this bundle. I can even create object number two from this

create object number two from this bundle. I can even create object number

bundle. I can even create object number three from this bundle and so on just to

three from this bundle and so on just to reuse these functions and variables

reuse these functions and variables again and

again and again. Oh, so that is the concept of

again. Oh, so that is the concept of class and an object. We first create a

class and an object. We first create a bundle, then we create objects. Same way

bundle, then we create objects. Same way you create a function and then you just

you create a function and then you just call it, right? And if you just want to

call it, right? And if you just want to save that particular output, you create

save that particular output, you create a variable. Same way here you will

a variable. Same way here you will create the class then you will create an

create the class then you will create an object instead of a variable you will

object instead of a variable you will create an object and you will reuse

create an object and you will reuse it. Make sense? That is the concept of

it. Make sense? That is the concept of objectoriented programming. That means

objectoriented programming. That means we focus on creating more and more

we focus on creating more and more objects. Make sense? This is the highle

objects. Make sense? This is the highle overview. Why do we need oop? Why do we

overview. Why do we need oop? Why do we need object- oriented

need object- oriented programming? Why do we need these

programming? Why do we need these things? Obviously there are like so many

things? Obviously there are like so many use cases. Reusability, polymorphism,

use cases. Reusability, polymorphism, inheritance, so many things but this is

inheritance, so many things but this is the fundamental. This is the

the fundamental. This is the fundamental make sense. Don't worry you

fundamental make sense. Don't worry you will learn everything in classes as

will learn everything in classes as well. So let's try to build a simple

well. So let's try to build a simple class and let's see what happens when we

class and let's see what happens when we just build a class. Okay, just be with

just build a class. Okay, just be with me. You will enjoy this oop session.

me. You will enjoy this oop session. Trust me, you will enjoy. You just just

Trust me, you will enjoy. You just just just be happy. Let's see what do we have

just be happy. Let's see what do we have in oop concepts. So let's try to build

in oop concepts. So let's try to build our first class. First class. First

our first class. First class. First class. Okay. Let me just close

class. Okay. Let me just close unnecessary tabs that are not required

unnecessary tabs that are not required now. So perfect. Let's create our class.

now. So perfect. Let's create our class. And trust me, class is very simple. It

And trust me, class is very simple. It looks like complex but it is very

looks like complex but it is very simple. Let's say we want to create a

simple. Let's say we want to create a class. And we just talked about classes.

class. And we just talked about classes. Class is just like a bundle. Let's say

Class is just like a bundle. Let's say within your company you have an

within your company you have an application for your whole organization

application for your whole organization and within that you want to bundle all

and within that you want to bundle all the functions and variables related to

the functions and variables related to employees. Make sense? What you will do?

employees. Make sense? What you will do? You will simply say class uh

You will simply say class uh employee. So you will simply create a

employee. So you will simply create a class called employee and how you create

class called employee and how you create that you simply write the keyword called

that you simply write the keyword called class and then the class

class and then the class name. Make sense? You will simply use

name. Make sense? You will simply use column and then just hit enter. This is

column and then just hit enter. This is the

the class. This is the class H. Okay. Okay.

class. This is the class H. Okay. Okay. Makes sense. Makes sense. Okay. Now, now

Makes sense. Makes sense. Okay. Now, now you will define the variables. Okay.

you will define the variables. Okay. Because you will simply group the

Because you will simply group the variables. I will simply say uh emp

variables. I will simply say uh emp name. Okay. EMP name. Let's say for now

name. Okay. EMP name. Let's say for now I'm just saying your name. Whatever. We

I'm just saying your name. Whatever. We can just pick any any any any loyal data

can just pick any any any any loyal data fam. So let's pick a random name.

fam. So let's pick a random name. Um Rahul Rahul is very popular name.

Um Rahul Rahul is very popular name. So okay let's pick this name. Now the

So okay let's pick this name. Now the company the company is obviously same.

company the company is obviously same. Let's say department. Okay department is

Let's say department. Okay department is let's say he works for IT. Okay do not

let's say he works for IT. Okay do not feel sad. We will just take your

feel sad. We will just take your examples as well. Okay makes sense.

examples as well. Okay makes sense. Okay. So employee name equals Rahul.

Okay. So employee name equals Rahul. employee department equals it. These are

employee department equals it. These are the variables. Now I want to create a

the variables. Now I want to create a function. Now you know how to create the

function. Now you know how to create the function. I will simply say df. I will

function. I will simply say df. I will say info which does nothing special. It

say info which does nothing special. It simply

simply returns the employee name and department

returns the employee name and department name. We will simply use fring. Now you

name. We will simply use fring. Now you know fring as well. I will simply say

know fring as well. I will simply say employee employee.

employee employee. employee emp

name. Okay. Works

for works for EMP department. Make sense? Whatever we will get in here.

sense? Whatever we will get in here. Whatever we will get in here. Can we

Whatever we will get in here. Can we just make it a little bit towards right?

just make it a little bit towards right? Can we? Can we? Can we? Can we?

Can we? Can we? Can we? Can we? Uh there should be a way. No h let me

Uh there should be a way. No h let me just decrease the size then. Okay, makes

just decrease the size then. Okay, makes sense. So this is the function okay that

sense. So this is the function okay that I created. Makes sense.

I created. Makes sense. Now this class is created obviously. But

Now this class is created obviously. But now when I will be running this, it will

now when I will be running this, it will throw an error. Why? Because you need to

throw an error. Why? Because you need to consider some things. Whenever you

consider some things. Whenever you create a function within the class, you

create a function within the class, you need to use a default parameter. Or you

need to use a default parameter. Or you can say mandatory parameter which is

can say mandatory parameter which is self. Self. Yes, self. We will just talk

self. Self. Yes, self. We will just talk about self as well as as well. Don't

about self as well as as well. Don't worry. So this is the thing that you

worry. So this is the thing that you have to use. Okay. Second thing. Second

have to use. Okay. Second thing. Second thing. This is the employee name. Okay.

thing. This is the employee name. Okay. And employee department. Obviously we

And employee department. Obviously we are

are using attributes. You will say no we are

using attributes. You will say no we are not using attributes. We are using

not using attributes. We are using variables. No. Whenever you are working

variables. No. Whenever you are working inside the class, your variables will be

inside the class, your variables will be called as

attributes. Okay? And your functions will be called as methods. So you need

will be called as methods. So you need to remember these things. Whenever I'm

to remember these things. Whenever I'm using words something called as methods

using words something called as methods and attributes, that means I'm referring

and attributes, that means I'm referring to function and variables. Make sense?

to function and variables. Make sense? Very good. These are some naming

Very good. These are some naming conventions that you need to use. This

conventions that you need to use. This is done. Let me just run this. Perfect.

is done. Let me just run this. Perfect. So this is done.

So this is done. Make sense? Makes sense. This is done.

Make sense? Makes sense. This is done. Like this is actually created. Okay. So

Like this is actually created. Okay. So now what we need to do? What we need to

now what we need to do? What we need to do? We will simply create an object. How

do? We will simply create an object. How we can just create object? Let's say

we can just create object? Let's say emp one or let's say emp1 is the object

emp one or let's say emp1 is the object of this particular class. Okay. I will

of this particular class. Okay. I will simply say

simply say employee. And that's it. That's it. I

employee. And that's it. That's it. I can simply run it. And this is all

can simply run it. And this is all obviously right. I will now access

obviously right. I will now access anything within this class. Let's say I

anything within this class. Let's say I want to access this variable or even if

want to access this variable or even if I want to access this variable or if I

I want to access this variable or if I just want to call this function, I can

just want to call this function, I can do anything using this

do anything using this template. Basically object of the

template. Basically object of the template because template is this one.

template because template is this one. This is the object. Okay. So now I can

This is the object. Okay. So now I can actually use anything. I will simply

actually use anything. I will simply write something like this.

write something like this. emp1 dot name and I can even print it. I

emp1 dot name and I can even print it. I will simply say print emp1.name name run

will simply say print emp1.name name run it error very good because I wanted to

it error very good because I wanted to see this it will simply say hey what are

see this it will simply say hey what are you doing man so here's the thing you

you doing man so here's the thing you need to use the same variable name okay

need to use the same variable name okay do not say like

do not say like name emp name very good it will simply

name emp name very good it will simply return Rahul makes sense I can even say

return Rahul makes sense I can even say emp

emp department okay I will simply see it

department okay I will simply see it very good if I just want to call the

very good if I just want to call the function I can do that. I will simply

function I can do that. I will simply say emp1 dot info and I will run this

say emp1 dot info and I will run this and it will

and it will work. No, it is saying hey emp name is

work. No, it is saying hey emp name is not

not defined. Here's the thing.

defined. Here's the thing. So whenever we are working with methods

So whenever we are working with methods what are methods functions we need to

what are methods functions we need to make sure that whatever we are using

make sure that whatever we are using here again I'm repeating we are using

here again I'm repeating we are using attributes what we are using attributes

attributes what we are using attributes what are attributes the variables that

what are attributes the variables that live inside the class very good so

live inside the class very good so whenever we want to use attributes we

whenever we want to use attributes we have to use a keyword called self we

have to use a keyword called self we have to write something like this 12 dot

have to write something like this 12 dot empame. Why? Because it tells that this

empame. Why? Because it tells that this particular employee name is coming from

particular employee name is coming from your

your class. It is not a normal variable or

class. It is not a normal variable or parameter of this function. No, it is

parameter of this function. No, it is coming from this class

coming from this class attributes. Make sense? Make sense? Make

attributes. Make sense? Make sense? Make sense? Very good. So I have to use

sense? Very good. So I have to use something like

something like this self dot and here as well self dot.

this self dot and here as well self dot. Okay I want to shift it but I cannot.

Okay I want to shift it but I cannot. Let's reduce the text size.

Let's reduce the text size. So

So yeah so this is the thing. Okay let's

yeah so this is the thing. Okay let's try to run now. It will simply say

try to run now. It will simply say employee Rahul works for it. Okay.

employee Rahul works for it. Okay. Employee Rahul works for it. Very good.

Employee Rahul works for it. Very good. Now what if I have what if I have a

Now what if I have what if I have a parameter here of the same name. Let's

parameter here of the same name. Let's say I have a parameter called employee

say I have a parameter called employee name and employee

name and employee department. Okay. Now you can use it

department. Okay. Now you can use it without self because you will pass these

without self because you will pass these parameters from here. You will simply

parameters from here. You will simply say let's

say let's say

say rohul or do not like use bad words love.

rohul or do not like use bad words love. Let let me use my word my my my name.

Let let me use my word my my my name. Okay. And you are passing let's say it.

Okay. And you are passing let's say it. Okay. If you just run this you will see

Okay. If you just run this you will see it will work. Why? Because this time

it will work. Why? Because this time this employee name is not this one. It

this employee name is not this one. It is coming from

is coming from here. That is why to distinguish between

here. That is why to distinguish between the

the parameters with the ones that are

parameters with the ones that are attributes we use self keyword. So even

attributes we use self keyword. So even if if I just take this variable and if I

if if I just take this variable and if I do not want to use that particular name

do not want to use that particular name I do not want to use love I can simply

I do not want to use love I can simply write here

write here self that's it and it will work and it

self that's it and it will work and it will simply say Rahul so we are saying

will simply say Rahul so we are saying that whenever I'm using self I'm using

that whenever I'm using self I'm using inner variables inner things and if I'm

inner variables inner things and if I'm just passing the normal parameters I'm

just passing the normal parameters I'm using the external

using the external ones make

ones make sense very good now you can ask me one

sense very good now you can ask me one thing if you haven't asked me this.

thing if you haven't asked me this. Okay, you will simply say an in this

Okay, you will simply say an in this parameter like in this list of

parameter like in this list of parameters we actually have three

parameters we actually have three parameters, right? Self, employee name

parameters, right? Self, employee name and employee department. But we are

and employee department. But we are passing only two or let's say even if we

passing only two or let's say even if we do not have these list, if we just have

do not have these list, if we just have self and if we just call this like

self and if we just call this like this, it still works. But actually you

this, it still works. But actually you are not passing any parameter. Why you

are not passing any parameter. Why you are not passing self parameter? I am

are not passing self parameter? I am passing the parameter but I'm not

passing the parameter but I'm not showing you an

showing you an Lamba do

Lamba do not do this. So the thing is actually I

not do this. So the thing is actually I am not passing the parameters. Python is

am not passing the parameters. Python is passing the parameters for me. So I

passing the parameters for me. So I created this object right and I am

created this object right and I am calling this function like this. But

calling this function like this. But actually behind the scenes what Python

actually behind the scenes what Python is doing? Python is making this function

is doing? Python is making this function call like this.

call like this. employee dot info then employee 1

employee dot info then employee 1 and then this will make the call. So if

and then this will make the call. So if I just run this you will see the same

I just run this you will see the same stuff. So this command is actually

stuff. So this command is actually equivalent to this one. But just to make

equivalent to this one. But just to make things easy because it doesn't make any

things easy because it doesn't make any sense to pass the object again and again

sense to pass the object again and again because this self keyword that means we

because this self keyword that means we are passing the object itself. You will

are passing the object itself. You will say what is the big deal? Why do we need

say what is the big deal? Why do we need to pass the object? You will get to know

to pass the object? You will get to know bro when I will just discuss the

bro when I will just discuss the constructors. Okay. So basically

constructors. Okay. So basically employee one is

employee one is different. Employee two will be

different. Employee two will be different. Employee three will be

different. Employee three will be different. employee four will be

different. employee four will be different. So that means every object

emp right. That means this function should behave different for different

should behave different for different objects. That is why we pass self as the

objects. That is why we pass self as the parameter. That means each object will

parameter. That means each object will act

act differently. Make sense? Make sense?

differently. Make sense? Make sense? That is why we pass self. Now we know

That is why we pass self. Now we know that we always need to pass the self

that we always need to pass the self command. So that is why we prefer using

command. So that is why we prefer using this one. Okay? Because this is handy

this one. Okay? Because this is handy and this is like quick. But actually

and this is like quick. But actually this command is doing like this. Class

this command is doing like this. Class name then function name and then passing

name then function name and then passing that particular object. So you should

that particular object. So you should know this right. Just take notes. Take

know this right. Just take notes. Take notes. Okay. Perfect. Now let's try to

notes. Okay. Perfect. Now let's try to understand the constructors. Okay. Now

understand the constructors. Okay. Now just tell me one thing. Just telling you

just tell me one thing. Just telling you one thing we are building this class,

one thing we are building this class, right? Let's say we have some fixed

right? Let's say we have some fixed attributes because these are the default

attributes because these are the default attributes of the employee class. So we

attributes of the employee class. So we know that all the employees will belong

know that all the employees will belong to the same company. Let's say company

to the same company. Let's say company name

name is company name is um

is company name is um XYZ. Okay. Let's say the company name is

XYZ. Okay. Let's say the company name is XYZ. This will be the constant. This

XYZ. This will be the constant. This will be constant thing. But now comes

will be constant thing. But now comes the dynamic thing. Let's say employee

the dynamic thing. Let's say employee name and employee department cannot be

name and employee department cannot be fixed because it will be different for

fixed because it will be different for each employee. So that's where we create

each employee. So that's where we create something called as constructor. What

something called as constructor. What constructor will do? Let me just show

constructor will do? Let me just show you. So in order to define the

you. So in order to define the constructor, we simply write this

def_init then simply braces for the function and then we simply write self.

function and then we simply write self. That's it.

That's it. That's it.

That's it. Now,

Now, whatever variables or you can say

whatever variables or you can say attributes you want to create

attributes you want to create dynamically, you will simply define

dynamically, you will simply define inside this. That means let's say you

inside this. That means let's say you want to define um employee name. You

want to define um employee name. You will simply write it here. Employee

will simply write it here. Employee name. Let's say you want to define um

name. Let's say you want to define um employee department. You will simply say

employee department. You will simply say employee department. Make sense? Now

employee department. Make sense? Now this function this function this is

this function this function this is called constructor by the way whenever

called constructor by the way whenever you will be calling this function like

you will be calling this function like calling this object let's say you are

calling this object let's say you are creating this object it will

creating this object it will automatically call this function let me

automatically call this function let me repeat let's say I'm writing it here

repeat let's say I'm writing it here pass okay and I'm not taking any kind

pass okay and I'm not taking any kind of parameters when we write pass means

of parameters when we write pass means um we just need to define the function

um we just need to define the function but we do not need to do anything

but we do not need to do anything otherwise it will throw error. So pass

otherwise it will throw error. So pass is very handy in that case. Okay, so

is very handy in that case. Okay, so this is fine. So what it actually did

this is fine. So what it actually did behind the scenes, let me show you. Let

behind the scenes, let me show you. Let me show you. Let's not use pass this

me show you. Let's not use pass this time. Let me just write print hello

time. Let me just write print hello baby. Let's run this. What? What? Why?

baby. Let's run this. What? What? Why? Why? Why are we seeing hello baby? Why?

Why? Why are we seeing hello baby? Why? Because I simply created this object. I

Because I simply created this object. I didn't call this function. I didn't

didn't call this function. I didn't write it like this. employee one then

write it like this. employee one then dot

dot init then like this I didn't do that why

init then like this I didn't do that why it simply return this function or

it simply return this function or basically why it executed this function

basically why it executed this function this is the power of constructor it will

this is the power of constructor it will every time the moment you create the

every time the moment you create the object it will simply run this function

object it will simply run this function which is def init like init cell or it

which is def init like init cell or it will simply you can say take this object

will simply you can say take this object as the parameter and run this. Wow, we

as the parameter and run this. Wow, we take the advantage of this opportunity.

take the advantage of this opportunity. What we do now? We know that we need to

What we do now? We know that we need to simply create two more parameters. It

simply create two more parameters. It says employee name equals let's say your

says employee name equals let's say your name. Let's take a girl's name this

name. Let's take a girl's name this time. Otherwise, you will say, "Hey,

time. Otherwise, you will say, "Hey, where's

so I don't know girl's name. Let's say Priya. Let's say okay I do not

Let's say Priya. Let's say okay I do not know any Priya just a hypothetical word.

know any Priya just a hypothetical word. Okay.

Okay. Employee department. Now you will say I

Employee department. Now you will say I want to hardcode it. Okay like not

want to hardcode it. Okay like not hardcode I want to define these

hardcode I want to define these variables but I want these two variables

variables but I want these two variables should come from a different object.

should come from a different object. That means employee one will have its

That means employee one will have its own employee name and department

own employee name and department employee two will have its own employee

employee two will have its own employee three will have its own. So I want these

three will have its own. So I want these names these attributes coming from

names these attributes coming from different objects. So what we can do

different objects. So what we can do obviously we

obviously we cannot we cannot create like this

cannot we cannot create like this because otherwise it will simply be same

because otherwise it will simply be same for every object. What we will do we

for every object. What we will do we will simply move these from here and I

will simply move these from here and I will put it under here. Make sense? Make

will put it under here. Make sense? Make sense? If not it will make sense very

sense? If not it will make sense very soon. Wait. Okay. And what I will do I

soon. Wait. Okay. And what I will do I will get these parameters from here.

will get these parameters from here. Employee

Employee name. Okay. And then employee

name. Okay. And then employee department. And this name will be what?

department. And this name will be what? It will become self dot employee

It will become self dot employee name. Okay. And it will become self dot

name. Okay. And it will become self dot employee department. So now what we

employee department. So now what we going to do like what what's what's

going to do like what what's what's happening here basically oh sorry uh not

happening here basically oh sorry uh not here

self self dot employee name and self dot this so what is happening here let me

this so what is happening here let me just tell you we know that when we'll be

just tell you we know that when we'll be creating this object this function will

creating this object this function will be triggered automatically so now it's

be triggered automatically so now it's our duty or you can say it's now

our duty or you can say it's now mandatory thing to pass these these two

mandatory thing to pass these these two parameters from the class. So this time

parameters from the class. So this time I will simply say let's say Priya and

I will simply say let's say Priya and then it so what it will do it will

then it so what it will do it will simply trigger this function like this

simply trigger this function like this one in it through this particular class

one in it through this particular class and these parameters Priya and it will

and these parameters Priya and it will go here. Okay. Then what we will do? We

go here. Okay. Then what we will do? We will simply define the class attribute.

will simply define the class attribute. Self dot employee name will become

Self dot employee name will become equals to this. And self dot employee

equals to this. And self dot employee department will be equals to

department will be equals to this.

this. H makes sense. Makes sense because if

H makes sense. Makes sense because if you remember this is the same stuff,

you remember this is the same stuff, right? Whatever we write here, it

right? Whatever we write here, it becomes self dot something. Because

becomes self dot something. Because whenever I want to use this variable at

whenever I want to use this variable at the end of the day, I will be using use

the end of the day, I will be using use I will be using it with the help of self

I will be using it with the help of self keyword. Right? So what we did we simply

keyword. Right? So what we did we simply defined self dot employee name equals to

defined self dot employee name equals to this word and self domply employee uh

this word and self domply employee uh department will become equals to this

department will become equals to this word. Make sense? Let me just run this

word. Make sense? Let me just run this then it will make sense. Okay. Perfect.

then it will make sense. Okay. Perfect. So now this is created. I will simply

So now this is created. I will simply call the function employee

call the function employee 1.info and I should

1.info and I should see perfect employee Priya works for it.

see perfect employee Priya works for it. So now you know what happened. We

So now you know what happened. We created dynamic attributes which are

created dynamic attributes which are coming from the

coming from the object H. So basically there are two

object H. So basically there are two types of attributes class attributes and

types of attributes class attributes and instance attributes. This is a class

instance attributes. This is a class attribute which is constant. These are

attribute which is constant. These are instance attributes which are subject to

instance attributes which are subject to the

the objects. Make sense? So again let me

objects. Make sense? So again let me just tell you the flow. This will

just tell you the flow. This will trigger this function in it. And now

trigger this function in it. And now this function has parameters. That means

this function has parameters. That means we have to define the parameters. Okay.

we have to define the parameters. Okay. So we defined it with prian. Now we

So we defined it with prian. Now we defined self dot employment name and

defined self dot employment name and self dot

self dot department using these two parameters

department using these two parameters that we got from the object. Now we can

that we got from the object. Now we can use these variables anywhere inside this

use these variables anywhere inside this class because now these are class

class because now these are class attributes. Now these are class

attributes. Now these are class attributes. Okay. Let's say I'm creating

attributes. Okay. Let's say I'm creating employee 2. Employee 2

employee 2. Employee 2 equals employee let's say

priu. Priyanchu he works for let's say HR. So now employee 1.info will return

HR. So now employee 1.info will return different results. Employee 2.info info

different results. Employee 2.info info will return different results and we

will return different results and we will see it here. See employee Priya

will see it here. See employee Priya works for IT. Employee Priyanka works

works for IT. Employee Priyanka works for HR. This is your basic example of a

for HR. This is your basic example of a class. This is the

class. This is the example. I hope it makes sense. I hope

example. I hope it makes sense. I hope now you have built a strong base with

now you have built a strong base with class like what is a class and what

class like what is a class and what things we need to just focus on and how

things we need to just focus on and how we just talk about classes. I know I

we just talk about classes. I know I know it looks really easy now because I

know it looks really easy now because I know how to just make you aware the

know how to just make you aware the things there's a flow that we need to

things there's a flow that we need to follow. Okay, make sense. So let me just

follow. Okay, make sense. So let me just see what we have discussed. Okay,

see what we have discussed. Okay, constructors are done because I do not

constructors are done because I do not want to compromise with this section.

want to compromise with this section. Classes are must and I have to cover all

Classes are must and I have to cover all the topics. Okay, very good.

the topics. Okay, very good. Now let's also talk about something.

Now let's also talk about something. Let's say you want to change

Let's say you want to change the value which is class class attribute

the value which is class class attribute for a kind of object. Can you do that?

for a kind of object. Can you do that? Yes. Let's say employee 2. Okay.

Yes. Let's say employee 2. Okay. Employee 2 actually works for a

Employee 2 actually works for a different company. Let's say so it will

different company. Let's say so it will simply say employee

simply say employee 2 dot company

2 dot company name company name equals

name company name equals ABC. So

ABC. So now

now if employee 2 says dot info we should

if employee 2 says dot info we should see something called as obviously it is

see something called as obviously it is not used anywhere. So that's why we are

not used anywhere. So that's why we are not seeing but you can actually see it

not seeing but you can actually see it using this as well.

using this as well. print emp2 dot company

print emp2 dot company name make sense it will return ABC

name make sense it will return ABC perfect now it is no more it is no more

perfect now it is no more it is no more xyz for employee two for employee two

xyz for employee two for employee two let me just minimize the screen yeah now

let me just minimize the screen yeah now it is no more employee two like no more

it is no more employee two like no more xyz for employee two now it is ABC and

xyz for employee two now it is ABC and it is evident print we can even print

it is evident print we can even print it. So we can even change these values

it. So we can even change these values as well using the objects because this

as well using the objects because this is just a template right this is just a

is just a template right this is just a template we can change it we can change

template we can change it we can change it but ideally we do not change the

it but ideally we do not change the values like this because what will

values like this because what will happen with this so let's

happen with this so let's say now a quick question can be before

say now a quick question can be before discussing the next thing um what will

discussing the next thing um what will be the value for employee one will that

be the value for employee one will that be changed as well

be changed as well no let's see employee 1 dot company

no let's see employee 1 dot company name let's see it's still XYZ so it is

name let's see it's still XYZ so it is just changed for employee 2 not for

just changed for employee 2 not for employee one that's the power of

employee one that's the power of objectoriented programming it is not

objectoriented programming it is not being changed for anything else you will

being changed for anything else you will say what if what if we want to change

say what if what if we want to change company name let's say you will say

company name let's say you will say hypothetical situation we want to change

hypothetical situation we want to change company name for all the objects you

company name for all the objects you will simply say one one option is like

will simply say one one option is like simply you can do it here which is not

simply you can do it here which is not recommended. Okay, this time you will

recommended. Okay, this time you will see ABC this is not recommended. There

see ABC this is not recommended. There are other ways as well how you can

are other ways as well how you can simply change the class attributes for

simply change the class attributes for the you can say all the objects you can

the you can say all the objects you can do that we will just discuss that as

do that we will just discuss that as well don't worry I know when you just

well don't worry I know when you just learn object-oriented programming you

learn object-oriented programming you get a lot of doubts but you need to hold

get a lot of doubts but you need to hold your emotions because everything will be

your emotions because everything will be discussed slowly slowly slowly okay okay

discussed slowly slowly slowly okay okay very good so now let's talk about how we

very good so now let's talk about how we can just change the class attribute or

can just change the class attribute or you can say class variable Because you

you can say class variable Because you know because so far you would have the

know because so far you would have the understanding that that you cannot

understanding that that you cannot change the default or you can say class

change the default or you can say class variable using object because that is

variable using object because that is specific to object only but even if you

specific to object only but even if you just want to change it obviously you

just want to change it obviously you should not change it from here like ABC

should not change it from here like ABC no that's not a good choice or you can

no that's not a good choice or you can say recommended approach so how we can

say recommended approach so how we can just do that so basically for that what

just do that so basically for that what we do we simply use the class name let's

we do we simply use the class name let's say employee so employee is class name

say employee so employee is class name we will simply say employee dot company

we will simply say employee dot company name

name equals let's say ABC okay now you can do

equals let's say ABC okay now you can do that and let me simply run it and now

that and let me simply run it and now you can even use

you can even use it let's say you want to create employee

it let's say you want to create employee one that is E1 or let's say oh employee

one that is E1 or let's say oh employee 1 is already there so employee 1 dot um

1 is already there so employee 1 dot um info so now it will simply give me okay

info so now it will simply give me okay it let's add one more thing here let's

it let's add one more thing here let's add works for department in company name

add works for department in company name self

okay perfect let's see uh what's wrong I forgot to close it

uh what's wrong I forgot to close it okay perfect so it is saying employee

okay perfect so it is saying employee Priya works for IT in

Priya works for IT in ABC make sense in or add whatever you

ABC make sense in or add whatever you want to say. So it is saying in ABC. So

want to say. So it is saying in ABC. So actual value was XYZ but we change this

actual value was XYZ but we change this value.

value. Wow.

Wow. Wow. So

Wow. So basically we also do not prefer this

basically we also do not prefer this way. This was just a de demonstration so

way. This was just a de demonstration so that you would understand how we can

that you would understand how we can actually change the value. We cannot use

actually change the value. We cannot use objects. We have to use employee name

objects. We have to use employee name that is class name. But this is also not

that is class name. But this is also not recommended because you cannot keep a

recommended because you cannot keep a track of it, right? Because this is just

track of it, right? Because this is just a piece of code which is referred

a piece of code which is referred outside the class. You should always

outside the class. You should always manage these changes through inside the

manage these changes through inside the class. Really? Yes. Always you should

class. Really? Yes. Always you should always do this. So how how we can just

always do this. So how how we can just do that?

do that? Basically there are so many ways to do

Basically there are so many ways to do that. So let's say you can create a

that. So let's say you can create a different function. Let's

different function. Let's say and we will just talk about that as

say and we will just talk about that as well in the getters and setters but

well in the getters and setters but ideally let me just give you a hint so

ideally let me just give you a hint so that you will hold your excitement. We

that you will hold your excitement. We can simply create a function okay let's

can simply create a function okay let's say changes and you can

say changes and you can actually change the values and you can

actually change the values and you can take the parameter let's say new

take the parameter let's say new company okay and then you can simply say

company okay and then you can simply say employee which is the class name okay

employee which is the class name okay then company

then company name okay

name okay equals new company make

equals new company make sense make sense make sense makes sense

sense make sense make sense makes sense makes sense if you just try to do do

makes sense if you just try to do do this if you just try to do this let's

this if you just try to do this let's try to run this and you will see like

try to run this and you will see like what will happen so let's say you are

what will happen so let's say you are running this

running this particular function okay you are running

particular function okay you are running this particular function so I can simply

this particular function so I can simply say um

say um emp1 dot changes and then I'm simply

emp1 dot changes and then I'm simply saying new company let's say company

saying new company let's say company name is new company okay and then we are

name is new company okay and then we are simply trying to see employee one not

simply trying to see employee one not employee one let's say employee two

employee one let's say employee two because it will be changed for everyone,

because it will be changed for everyone, right? Employee

right? Employee 2.info. Let's see what happened. So, it

2.info. Let's see what happened. So, it has successfully changed this thing.

has successfully changed this thing. Why? Because we have a dedicated

Why? Because we have a dedicated function called changes which can

function called changes which can actually

actually change which can actually change

change which can actually change the class variable or you can say class

the class variable or you can say class attributes. This is a better way of

attributes. This is a better way of doing it. Instead of just changing it

doing it. Instead of just changing it from outside the class, you should

from outside the class, you should always change it within the class. Look

always change it within the class. Look like from inside the class using

like from inside the class using obviously the function like this DF

obviously the function like this DF changes. Now obviously we should not

changes. Now obviously we should not allow to use this function to anyone

allow to use this function to anyone because any object can change anything.

because any object can change anything. Obviously that's a different story.

Obviously that's a different story. We'll just talk about that as well. But

We'll just talk about that as well. But I'm just showing you that this is

I'm just showing you that this is possible and this is the way that we

possible and this is the way that we should make the changes instead of from

should make the changes instead of from outside the

outside the class. Make sense? Make sense? Makes

class. Make sense? Make sense? Makes sense. Very good. Let's try to

sense. Very good. Let's try to understand, static

understand, static method, class method and instance

method, class method and instance methods. So

methods. So basically we already know that these are

basically we already know that these are all methods, right? These are all

all methods, right? These are all methods. Method method method. So

methods. Method method method. So basically these methods have a kind of

basically these methods have a kind of different different categories. So far

different different categories. So far we were only working with instance

we were only working with instance methods. Okay, these were instance

methods. Okay, these were instance methods which are specific to an

methods which are specific to an instance, right? Employee one will

instance, right? Employee one will behave differently like these methods

behave differently like these methods will behave differently for employee

will behave differently for employee one, same for employee two and so on. So

one, same for employee two and so on. So these are your employee like of the

these are your employee like of the employee class. These are

employee class. These are your instance methods. Okay, we have two

your instance methods. Okay, we have two more methods. We have something called

more methods. We have something called as let's say static methods. First of

as let's say static methods. First of all, let's talk about this. What are

all, let's talk about this. What are static methods? Okay, so we have

static methods? Okay, so we have something called as static methods and

something called as static methods and then we have class methods. We'll just

then we have class methods. We'll just talk about after that. So static

talk about after that. So static methods, these methods are you can say

methods, these methods are you can say junk methods. Why? Why junk? because

junk methods. Why? Why junk? because they are not directly related to your

they are not directly related to your class. They are not directly related to

class. They are not directly related to the logic but they are still there

the logic but they are still there because they just need to be shifted

because they just need to be shifted when you are just let's say migrating

when you are just let's say migrating your code or you just want to perform

your code or you just want to perform something within this class. For

something within this class. For example, let's say you have a function

example, let's say you have a function called addition. Okay, addition or you

called addition. Okay, addition or you can say a kind

can say a kind of yeah

of yeah addition. Okay, now you will simply get

addition. Okay, now you will simply get two parameters. Let's say x and

two parameters. Let's say x and y. That's it. And you will simply return

y. That's it. And you will simply return or print let's

or print let's say x + y. That's it. You will say an

say x + y. That's it. You will say an lamba anala just just put um self. You

lamba anala just just put um self. You forgot to add self. No. When you just

forgot to add self. No. When you just create static

create static method, you do not need any kind of self

method, you do not need any kind of self method because it is not related to any

method because it is not related to any object. It is not related to any kind of

object. It is not related to any kind of you can say these attributes, these

you can say these attributes, these class attributes, instance attributes,

class attributes, instance attributes, nothing. These are like not related to

nothing. These are like not related to these things. So why do we use that?

these things. So why do we use that? Let's say within your class you just

Let's say within your class you just want to keep this function to just

want to keep this function to just perform some basic stuff which are

perform some basic stuff which are irrelevant or indirectly linked to other

irrelevant or indirectly linked to other things within the same class. So let's

things within the same class. So let's say I have this employee one. Okay, I

say I have this employee one. Okay, I have created this object. I just want to

have created this object. I just want to perform um basic mathematics of

perform um basic mathematics of addition. I will simply say emp1 dot

addition. I will simply say emp1 dot addition and I will simply get one and

addition and I will simply get one and two. Okay, one and two. Let me comment

two. Okay, one and two. Let me comment it out other things and let's see what

it out other things and let's see what it will return. it will return very

it will return. it will return very good. So by the way this error

good. So by the way this error was intentional. So this by the way if

was intentional. So this by the way if you're just working with classes for

you're just working with classes for let's say if it is your first time you

let's say if it is your first time you will actually see this error a lot. It

will actually see this error a lot. It will simply say employee. Okay takes two

will simply say employee. Okay takes two positional arguments but three were

positional arguments but three were given. You will simply say hey I have

given. You will simply say hey I have just given two parameters who gave

just given two parameters who gave three. Remember whenever you make the

three. Remember whenever you make the call like this? Whenever you make the

call like this? Whenever you make the call like this it will automatically

call like this it will automatically pass the employee one as well. remember

pass the employee one as well. remember because behind the scenes it is running

because behind the scenes it is running something like

something like this

this employee dot

employee dot addition then 1 comma

addition then 1 comma 2 and before 1 comma 2 you can simply

2 and before 1 comma 2 you can simply add emp1 as well but I'm writing it here

add emp1 as well but I'm writing it here okay so in total you are passing three

okay so in total you are passing three parameters so what's the solution of it

parameters so what's the solution of it what's the solution of it so the

what's the solution of it so the solution

solution is we need to tell Python that this is

is we need to tell Python that this is not your regular instance method. This

not your regular instance method. This is a static method. You simply need to

is a static method. You simply need to write

write static method. Now you can simply try

static method. Now you can simply try running this because otherwise it will

running this because otherwise it will treat it as like your normal method

treat it as like your normal method which is your instance method. So we

which is your instance method. So we need to tell hey this is a static

need to tell hey this is a static method.

method. Okay. Wow this was amazing. So it is

Okay. Wow this was amazing. So it is just a kind of you can say function

just a kind of you can say function which we need to just use within the

which we need to just use within the class. That's it. It is not directly

class. That's it. It is not directly linked to your attributes or anything.

linked to your attributes or anything. Make sense? Very good. Now let's try to

Make sense? Very good. Now let's try to discuss what are class methods. What are

discuss what are class methods. What are class

class methods? Class methods are originally

methods? Class methods are originally used to interact with your class

used to interact with your class attributes. Let's say you have your

attributes. Let's say you have your class attribute here company name. So

class attribute here company name. So class methods should be used to interact

class methods should be used to interact directly to your class attributes. You

directly to your class attributes. You will simply say an we are already

will simply say an we are already communicating it here. But let's say you

communicating it here. But let's say you have 100 functions inside this class.

have 100 functions inside this class. Can you just understand like will this

Can you just understand like will this function be directly linked to a class

function be directly linked to a class variable or let's say sorry class

variable or let's say sorry class method? Can you just predict that? No.

method? Can you just predict that? No. So that is why we have a special

So that is why we have a special decorator. It's

decorator. It's called class method. When we write class

called class method. When we write class method now we know that hey this

method now we know that hey this function is specifically built to

function is specifically built to interact with

interact with the class attributes make sense using

the class attributes make sense using this using this you get the special

this using this you get the special power what's that you can actually

power what's that you can actually change the value same way so you now do

change the value same way so you now do not need to write this thing okay

not need to write this thing okay because it is let me just create a new

because it is let me just create a new one so that you can actually compare it

one so that you can actually compare it so this particular function if you just

so this particular function if you just want to achieve the same results using

want to achieve the same results using class method. You will build like this

class method. You will build like this class

class method. Okay. Then you will simply

method. Okay. Then you will simply create a function. It's called let's say

create a function. It's called let's say changes in class. Okay. I will simply

changes in class. Okay. I will simply say self. Then I will simply say new

say self. Then I will simply say new company. Okay. Now I will simply say

company. Okay. Now I will simply say self dot company

self dot company name equals new

name equals new company. Because this is a class method,

company. Because this is a class method, it understands that this self keyword is

it understands that this self keyword is not for the object. This is for the

not for the object. This is for the class itself. This is for the class

class itself. This is for the class itself. Let me just run this. So

itself. Let me just run this. So everything is fine because there's no

everything is fine because there's no error. But you will say an we are still

error. But you will say an we are still feeling that we can feel confused

feeling that we can feel confused because self keyword we use for objects.

because self keyword we use for objects. Yes. Um if we will be using it with

Yes. Um if we will be using it with class it can become confusing and we

class it can become confusing and we know that we have a decorator called

know that we have a decorator called class method but still it can be

class method but still it can be confusing. Exactly. That is why whenever

confusing. Exactly. That is why whenever you define a class method you have the

you define a class method you have the liberty to change this name. You can

liberty to change this name. You can give any name and as per the industry we

give any name and as per the industry we give name called cls class that means we

give name called cls class that means we are referring to the class attributes

are referring to the class attributes this is a like industry standard we use

this is a like industry standard we use cls you can just use anything you can

cls you can just use anything you can use like let's

use like let's say anything let's say protein let's say

say anything let's say protein let's say anything okay you can just put

anything okay you can just put anything so it's up to you even if you

anything so it's up to you even if you use self it will work but just for the

use self it will work but just for the readability and as per the industry

readability and as per the industry standards it will work. Let me just show

standards it will work. Let me just show you. Let's say I want to make this call

you. Let's say I want to make this call with any object I will simply

with any object I will simply say

say changes in class. I'll simply say new

changes in class. I'll simply say new new

new company. Okay. And then I will simply

company. Okay. And then I will simply say emp1

dot print of emp1 dot company name okay let's

name okay let's see new new company see so it is just a

see new new company see so it is just a naming convention but you should always

naming convention but you should always use cls because it will be easy to

use cls because it will be easy to interpret okay this is for cls class now

interpret okay this is for cls class now the same stuff can be achieved using

the same stuff can be achieved using this function as well but it is not

this function as well but it is not recommended Ed because it is not good

recommended Ed because it is not good when you have so many functions. Okay,

when you have so many functions. Okay, it is literally doesn't make any sense.

it is literally doesn't make any sense. That's why we have decorators. We should

That's why we have decorators. We should always use decorators. Plus, it promotes

always use decorators. Plus, it promotes you can say standard approach. Why?

you can say standard approach. Why? Because see all the other functions are

Because see all the other functions are similar like company name dot company

similar like company name dot company name blah blah blah. Here it is using

name blah blah blah. Here it is using the class name. So it it doesn't make

the class name. So it it doesn't make any sense. So that is why instead of

any sense. So that is why instead of using this one, you can use this. Again,

using this one, you can use this. Again, it is just a programming. It's up to

it is just a programming. It's up to developer what code they want to just

developer what code they want to just prefer. Okay. So it's up to you. So it

prefer. Okay. So it's up to you. So it is the same thing. I can simply write

alternative alternative to class method. I know it

alternative to class method. I know it is not visible so can't help. So so so

is not visible so can't help. So so so make sense. Let me just use white light.

make sense. Let me just use white light. Oh wow. Wow. Good

Oh wow. Wow. Good morning. Let's use this one. This is

morning. Let's use this one. This is also good. Okay. Perfect. So as you can

also good. Okay. Perfect. So as you can see now comments now you can see the

see now comments now you can see the comments. I know developers like this

comments. I know developers like this thing this thing. Wow. Yellow color

thing this thing. Wow. Yellow color white color. Okay. But this is also

white color. Okay. But this is also nice. This is also nice. Okay. Perfect.

nice. This is also nice. Okay. Perfect. So this was all about your instance

So this was all about your instance methods class methods and static

methods class methods and static methods. I hope now it is very much

methods. I hope now it is very much clear. I hope. Now let's see what do we

clear. I hope. Now let's see what do we have next. Let's talk about getters and

have next. Let's talk about getters and setters. So basically as the name

setters. So basically as the name suggest getters and setters getter

suggest getters and setters getter function or you can say getter method is

function or you can say getter method is used to return the values basically to

used to return the values basically to get the values get the

get the values get the values whereas on the other hand setter

values whereas on the other hand setter is used to set the values to set the

is used to set the values to set the values basically to let's say um set the

values basically to let's say um set the um

um instance attributes

instance attributes So this behaves exactly similar but

So this behaves exactly similar but syntax is a little bit complex but the

syntax is a little bit complex but the concept is very easy. So first of all

concept is very easy. So first of all we'll try to get like have the concepts

we'll try to get like have the concepts clear in our mind. Once the concepts are

clear in our mind. Once the concepts are clear then we will just switch to

clear then we will just switch to getters and setters because getters and

getters and setters because getters and setters can be achieved through your

setters can be achieved through your normal functions normal methods as well.

normal functions normal methods as well. But once you grab the concept getters

But once you grab the concept getters and setters are like your go-to buddy

and setters are like your go-to buddy for all those things. So let me first

for all those things. So let me first you make you understand like what are

you make you understand like what are the getters and setters concepts and

the getters and setters concepts and then we will simply try to shift our

then we will simply try to shift our code to getters and setters. Let me just

code to getters and setters. Let me just so first of all let me just turn off the

so first of all let me just turn off the lights. Woohoo. Perfect. So basically

lights. Woohoo. Perfect. So basically let's say let's say let me first first

let's say let's say let me first first of all remove this class method. We do

of all remove this class method. We do not need it. Or maybe let's keep it. No

not need it. Or maybe let's keep it. No worries. So let's say we are trying to

worries. So let's say we are trying to create one method which is called show

create one method which is called show me. Okay. Show

me. Okay. Show me. Make sense? And obviously we need to

me. Make sense? And obviously we need to use self because it's just an uh just an

use self because it's just an uh just an instance method. Okay. Within this it

instance method. Okay. Within this it will simply show us all the details. All

will simply show us all the details. All the details. Okay. Or I think we already

the details. Okay. Or I think we already have a function which is similar to show

have a function which is similar to show me because it is just showing the

me because it is just showing the information. Let's use this one. Let's

information. Let's use this one. Let's use this

use this one. Okay. Perfect. So we are using this

one. Okay. Perfect. So we are using this info function and let me just cut and

info function and let me just cut and paste at the top so that you can

paste at the top so that you can actually focus on this.

actually focus on this. Okay, perfect. Uh perfect. So basically

Okay, perfect. Uh perfect. So basically what this function is doing this

what this function is doing this function is returning all the things

function is returning all the things employee name, employee department and

employee name, employee department and company name. Make sense? That's what a

company name. Make sense? That's what a getter function does. Makes sense. Now

getter function does. Makes sense. Now let's say I want to change the value for

let's say I want to change the value for this particular object or basically

this particular object or basically object is employee one. Let's say the

object is employee one. Let's say the values before

values before were Priya and ID. Okay. So I can simply

were Priya and ID. Okay. So I can simply say employee 1 dot info and I should see

say employee 1 dot info and I should see those stuff. Okay. Perfect. Now let's

those stuff. Okay. Perfect. Now let's say I want to change the value. How I

say I want to change the value. How I can just do that? I can even use like

can just do that? I can even use like this. If you think you can use this,

this. If you think you can use this, let's say employee 1 dot

let's say employee 1 dot empame equals let's say Priya, she needs

empame equals let's say Priya, she needs to add one more a. Okay. And employee 1

to add one more a. Okay. And employee 1 dot employee department equals let's say

dot employee department equals let's say HR let's say now if I just call this

HR let's say now if I just call this function what will

function what will happen? Let's see what will happen. It

happen? Let's see what will happen. It will work. Okay. So this is the basic

will work. Okay. So this is the basic way to update

way to update the instance attributes. Makes sense?

the instance attributes. Makes sense? But we just talked about that we should

But we just talked about that we should not do this from outside the class. We

not do this from outside the class. We should have a function for it. So what

should have a function for it. So what we will do now? We will simply create a

we will do now? We will simply create a function

function called

called def change info. Okay. And within this

def change info. Okay. And within this we'll simply get employee name or

we'll simply get employee name or basically new employee

basically new employee name. Okay. And then new employee

name. Okay. And then new employee department. Make sense? Within this what

department. Make sense? Within this what we will do? We'll simply say self dot

we will do? We'll simply say self dot employee name equals new employee name.

employee name equals new employee name. self dot employee

department equals new employee department make sense. So if we just run

department make sense. So if we just run this what will happen? We can even

this what will happen? We can even change our info from this function

change our info from this function because we will simply call this

because we will simply call this function and this will simply change

function and this will simply change employee name and employee department

employee name and employee department for that particular instance which is

for that particular instance which is employee one. Let's do this. I will

employee one. Let's do this. I will simply say employee.info. Then I will

simply say employee.info. Then I will call this function employee 1 dot change

call this function employee 1 dot change info. I will simply

info. I will simply say priya and HR. So we should see this

say priya and HR. So we should see this difference. Perfect. It worked. It

difference. Perfect. It worked. It worked very well. So this function is

worked very well. So this function is called getter and I'm just talking about

called getter and I'm just talking about the concept. Okay. This is your getter

the concept. Okay. This is your getter and this is your setter. If you just

and this is your setter. If you just want to use traditional approach like

want to use traditional approach like achieving the same results without using

achieving the same results without using getter and setter. Okay. So this is your

getter and setter. Okay. So this is your getter. This is your setter. Now if you

getter. This is your setter. Now if you just want to use getter and setter

just want to use getter and setter method the way that we use within a

method the way that we use within a class let me just tell you now this is

class let me just tell you now this is really gamechanging. Let me just comment

really gamechanging. Let me just comment it out. So we know that this is our

it out. So we know that this is our getter function. Make sense? This will

getter function. Make sense? This will be our getter function. We will simply

be our getter function. We will simply add a decorator here. We will simply say

add a decorator here. We will simply say property. That means this is our

property. That means this is our getter. Make sense? This is our getter

getter. Make sense? This is our getter function. Now we need to create a setter

function. Now we need to create a setter function. Setter function is very

function. Setter function is very special. How? In order to create setter

special. How? In order to create setter function, you simply need to write at

function, you simply need to write at the rate info that is the same name.

the rate info that is the same name. Okay. info dot setter

Okay. info dot setter because because this is the setter for

because because this is the setter for this particular function of getter.

this particular function of getter. Okay, info dot setter and then you

Okay, info dot setter and then you simply need to have the parameters

simply need to have the parameters self, employee name that is new employee

self, employee name that is new employee name and new employee department. Make

name and new employee department. Make sense? Very good. Now within this you

sense? Very good. Now within this you will create another function with the

will create another function with the same name info. Oh wow this is amazing.

same name info. Oh wow this is amazing. Yes. So basically these things will go

Yes. So basically these things will go here. Okay. These things will go

here. Okay. These things will go here. Perfect. So this way you will

here. Perfect. So this way you will create the same function with the same

create the same function with the same name and this will be your setter. This

name and this will be your setter. This will be your getter. Don't worry you

will be your getter. Don't worry you will not be confused while calling it.

will not be confused while calling it. Don't worry. I will just show you how to

Don't worry. I will just show you how to call these functions. So basically this

call these functions. So basically this will perform the same stuff like self

will perform the same stuff like self dot something like we are doing here. I

dot something like we are doing here. I can simply copy and paste

can simply copy and paste it. Perfect. So what it will do? It will

it. Perfect. So what it will do? It will simply make the changes in my

simply make the changes in my particular attributes. Make sense? Okay.

particular attributes. Make sense? Okay. This is my setup. So now in order

This is my setup. So now in order to use this there's a different way.

to use this there's a different way. First of all, let's make sure like

First of all, let's make sure like everything is fine. Let's run this.

everything is fine. Let's run this. Okay, error. Where's the error?

Okay, error. Where's the error? Unexpected indent. Oh man, this

Unexpected indent. Oh man, this indentation. Um. Oh, we may need to use

indentation. Um. Oh, we may need to use this. Noops. Wait, wait, wait. Uh, this.

this. Noops. Wait, wait, wait. Uh, this. Oh,

Oh, no. What's the What's the What's the

no. What's the What's the What's the Wait, am I using the same name? info.

Wait, am I using the same name? info. Info. Okay. Dot setter. Yes. Oh, silly

Info. Okay. Dot setter. Yes. Oh, silly mistake. You do not need to indent your

mistake. You do not need to indent your function within the setter. I was like,

function within the setter. I was like, what's wrong with this syntax? So, let's

what's wrong with this syntax? So, let's see if it is fine. Yeah, it is fine.

see if it is fine. Yeah, it is fine. Now, you will say this function is also

Now, you will say this function is also info. This function is also info. How we

info. This function is also info. How we will call these functions? There's a

will call these functions? There's a special trick to call these functions.

special trick to call these functions. Now, this time if you want to call this

Now, this time if you want to call this function, obviously you will first of

function, obviously you will first of all create the object. Now you will not

all create the object. Now you will not call this functions like this like this.

call this functions like this like this. No, you will simply say

No, you will simply say print employee 1.info. You will treat

print employee 1.info. You will treat this function as your attribute. See

this function as your attribute. See perfect. You will treat this function as

perfect. You will treat this function as your

your attribute. Now if you just want to call

attribute. Now if you just want to call this function now, so you will do

this function now, so you will do something like this. employee

something like this. employee 1 dot info equals to because you have

1 dot info equals to because you have two parameters so you simply need to

two parameters so you simply need to provide two parameters you will simply

provide two parameters you will simply say simply pass a list and we will

say simply pass a list and we will simply say priya and then HR now this

simply say priya and then HR now this list will go here in this particular

list will go here in this particular parameter so I have removed this

parameter so I have removed this parameter with the earlier parameters

parameter with the earlier parameters earlier parameters were looking like

earlier parameters were looking like this new employee new employee name and

this new employee new employee name and new employee department. So the thing is

new employee department. So the thing is we cannot pass like

we cannot pass like multiple parameters. We should always

multiple parameters. We should always pass like one parameter. So we will

pass like one parameter. So we will simply pass only one. I'll simply say

simply pass only one. I'll simply say new employee details. Make sense? So

new employee details. Make sense? So this will be a list. We will play smart.

this will be a list. We will play smart. What we will do? We will simply say new

What we will do? We will simply say new employee

employee name equals new employee

name equals new employee details of zero index because we know

details of zero index because we know there are like two entities within that.

there are like two entities within that. That's why fundamentals help you a lot

That's why fundamentals help you a lot to debug things. Employee name or let's

to debug things. Employee name or let's say employee department equals new

say employee department equals new employee

employee details of one index. That makes sense.

details of one index. That makes sense. That's sorted. Now we can simply say

That's sorted. Now we can simply say employee 1 dot

employee 1 dot um

um info and we can simply say

print. Makes sense. Let's see what do we get. Okay, perfect. Priya works for HR

get. Okay, perfect. Priya works for HR in XYZ. Perfect. So this is the

in XYZ. Perfect. So this is the setter. This is the

setter. This is the setter and this is the

setter and this is the getter. This is the getter. Make sense?

getter. This is the getter. Make sense? Setter and getter I hope are now clear.

Setter and getter I hope are now clear. So we simply first of all created our

So we simply first of all created our normal function which is getter. We

normal function which is getter. We created property. We added property

created property. We added property decorator on top of it. That will be

decorator on top of it. That will be acted as a getter. Then we simply used

acted as a getter. Then we simply used this function. Okay. Add the rate info

this function. Okay. Add the rate info setter. Then we created the same

setter. Then we created the same function of same name but obviously we

function of same name but obviously we are using a different code. We are just

are using a different code. We are just updating the values that is self dot

updating the values that is self dot employee name equals to this and this.

employee name equals to this and this. That's it. And how we can just call it?

That's it. And how we can just call it? We need to call it like a

We need to call it like a um attribute. And we need to call the

um attribute. And we need to call the setter like an attribute as well.

setter like an attribute as well. Simple. That's the concept of your like

Simple. That's the concept of your like getters and setters in Python. Make

getters and setters in Python. Make sense? Very good. Let's see what do we

sense? Very good. Let's see what do we have next. Let's talk about inheritance.

have next. Let's talk about inheritance. I know this is the most scared area and

I know this is the most scared area and trust me, trust me in just few minutes

trust me, trust me in just few minutes you will master it. Inheritance. So

you will master it. Inheritance. So basically why do we need inheritance and

basically why do we need inheritance and what does it mean actually? So let's say

what does it mean actually? So let's say inheritance is just like a kind of

inheritance is just like a kind of biological term in which we say there

biological term in which we say there will be a parent then there will be a

will be a parent then there will be a child let's say then its child then its

child let's say then its child then its child same concept is applied here as

child same concept is applied here as well in the python inheritance. So what

well in the python inheritance. So what will happen? Let's say you have a class.

will happen? Let's say you have a class. Okay, you have a class. You have a class

Okay, you have a class. You have a class called employ. Um company. Let's start

called employ. Um company. Let's start from here. Company.

from here. Company. Okay.

Okay. Then you have a class called employee,

Then you have a class called employee, right?

right? Then let's say you have a

Then let's say you have a class

called let's say hobbies. Hobbies let's say. So we know that we already have a

say. So we know that we already have a kind of inheritance. We have a kind of

kind of inheritance. We have a kind of hierarchy. Class company is the parent

hierarchy. Class company is the parent class. Right?

class. Right? And if we are creating a new class

And if we are creating a new class called

called employee, obviously we would need all

employee, obviously we would need all the functions, all the variables that

the functions, all the variables that would be there in this

would be there in this class. Make sense? Because obviously it

class. Make sense? Because obviously it is linked to employee as

is linked to employee as well. Then we do not need to recreate

well. Then we do not need to recreate all the functions that means all the

all the functions that means all the methods. We do not need to recreate all

methods. We do not need to recreate all the attributes. What we will simply do?

the attributes. What we will simply do? We will simply inherit this class while

We will simply inherit this class while creating the employee class. Within just

creating the employee class. Within just click, you will actually import

click, you will actually import everything from the class

everything from the class company. Make sense? This is the concept

company. Make sense? This is the concept of

of inheritance. Then let's say you are

inheritance. Then let's say you are creating a new class called hobbies.

creating a new class called hobbies. Obviously, obviously if you are just

Obviously, obviously if you are just trying to create a hobbies class, you

trying to create a hobbies class, you would just need to get all the

would just need to get all the information of the employees because

information of the employees because hobbies will belong to the employees.

hobbies will belong to the employees. Makes sense?

Makes sense? Then instead of creating all the

Then instead of creating all the methods, all the attributes, you will

methods, all the attributes, you will simply

simply import or if I just talk with technical

import or if I just talk with technical terms, you will simply inherit the class

terms, you will simply inherit the class employee. We have so many levels

employee. We have so many levels actually. We have single level. Okay. We

actually. We have single level. Okay. We have

have multi-level. we have multiple

multi-level. we have multiple level. So these are three

level. So these are three major inheritance levels that we're

major inheritance levels that we're going to talk today. Let's actually get

going to talk today. Let's actually get started with the single level

started with the single level inheritance and let's see how it

inheritance and let's see how it behaves. And for this inheritance topic,

behaves. And for this inheritance topic, I was first thinking to just touch up

I was first thinking to just touch up from the you can say top. Okay, but then

from the you can say top. Okay, but then I thought like let's actually dive

I thought like let's actually dive deeper inside this topic because this is

deeper inside this topic because this is really really helpful and let me just

really really helpful and let me just show you how you can just work with

show you how you can just work with inheritance. So let's start fresh. Let's

inheritance. So let's start fresh. Let's remove all the things. Let's say we are

remove all the things. Let's say we are first of all creating a class called

first of all creating a class called company.

company. Okay, perfect. Within this we will

Okay, perfect. Within this we will simply create a

simply create a constructor or let's not start with

constructor or let's not start with constructor. Let me just first show you

constructor. Let me just first show you the concept then you'll simply dive

the concept then you'll simply dive deeper with complex scenarios. So let's

deeper with complex scenarios. So let's say you have just a simple function

say you have just a simple function called

called company info.

company info. Okay, which simply turns company name

is now let's say XYZ. Okay, that's it. This is the class.

XYZ. Okay, that's it. This is the class. Then you created a new class called

Then you created a new class called employee. And within this you have a

employee. And within this you have a function called employee

function called employee info. Okay. Within

info. Okay. Within this you are simply saying employee

this you are simply saying employee name is

name is um let's say

um let's say um anything. Let's say Priya. Who is

um anything. Let's say Priya. Who is Priya man? Just say Rahul.

Priya man? Just say Rahul. So this is the second class.

So this is the second class. Now I want to also call this function

Now I want to also call this function from this class. So instead of let's say

from this class. So instead of let's say copy pasting it here and recreating all

copy pasting it here and recreating all the functions, I will simply say inherit

the functions, I will simply say inherit company class while creating the

company class while creating the employee class. That's it. Now what will

employee class. That's it. Now what will happen if I

happen if I create employee one object just for this

create employee one object just for this class? just for this class. Okay, I will

class? just for this class. Okay, I will simply say employee that's it. If I say

simply say employee that's it. If I say employee 1 dot employee info, you will

employee 1 dot employee info, you will say that makes sense because we know

say that makes sense because we know that we can just access that particular

that we can just access that particular function. Okay. Um what's wrong? Wait.

function. Okay. Um what's wrong? Wait. Oh,

self. Okay. Self. Let's run this. Perfect. Employee name is Rahul.

Perfect. Employee name is Rahul. This is like very basic stuff. Can I run

This is like very basic stuff. Can I run this function as well? Because there's a

this function as well? Because there's a separate class and there's no object for

separate class and there's no object for this class. Yes, you can do that.

this class. Yes, you can do that. Really?

Really? Yes, you can do that. Perfect. How it

Yes, you can do that. Perfect. How it was possible? How? Because you inherited

was possible? How? Because you inherited this class. You inherited this class.

this class. You inherited this class. That means all these functions are

That means all these functions are accessible from this class as well.

accessible from this class as well. This is your single level

This is your single level inheritance. Single

inheritance. Single level. Okay. Let's now make it complex

level. Okay. Let's now make it complex because now you understood the concept.

because now you understood the concept. Let's make it complex. So the thing

Let's make it complex. So the thing is this is very simple. If you just want

is this is very simple. If you just want to understand the concept but actually

to understand the concept but actually in the real

in the real world you will have constructors as

world you will have constructors as well. And when we have constructors it

well. And when we have constructors it becomes hard to work with inheritance.

becomes hard to work with inheritance. Let's say you have a constructor

Let's say you have a constructor called

called DF in it and then self obviously then

DF in it and then self obviously then company name. Okay, very good. And you

company name. Okay, very good. And you will simply say self dot company name

will simply say self dot company name equals company name. Make

equals company name. Make sense? Same thing here as well. You

sense? Same thing here as well. You have constructor here as well. You will

have constructor here as well. You will say what's the big deal? What wh why it

say what's the big deal? What wh why it is a big deal? I will just tell you wait

is a big deal? I will just tell you wait here it will be employee

here it will be employee name

okay employee name perfect makes sense now tell me one

name perfect makes sense now tell me one thing will it work it work will it work

thing will it work it work will it work no

no why because the answer is simple let's

why because the answer is simple let's say let's make this you can is a

say let's make this you can is a function a little bit

function a little bit complex. I am inheriting company class

complex. I am inheriting company class and there's a reason behind it. So if I

and there's a reason behind it. So if I want to use functions or you can say

want to use functions or you can say even the attributes. So let's first of

even the attributes. So let's first of all make it dynamic. We will simply

all make it dynamic. We will simply say f and

say f and then self dot company name. Right?

then self dot company name. Right? Okay, makes sense. This is perfect.

Okay, makes sense. This is perfect. Similarly, here as well, employee name

is self dot employee name. Okay, perfect.

perfect. So now what we need to do, what we need

So now what we need to do, what we need to do, you'll simply say, okay, this

to do, you'll simply say, okay, this should be fine. This should be fine. And

should be fine. This should be fine. And actually truly speaking when I will just

actually truly speaking when I will just try to run this, let's say I'm trying to

try to run this, let's say I'm trying to access

access um this function employee

um this function employee info. Okay, if I just try to run this, I

info. Okay, if I just try to run this, I will see the error. By the way, this is

will see the error. By the way, this is just due to the missing curly braces.

just due to the missing curly braces. And let's see if everything is fine.

And let's see if everything is fine. Okay. Oh, just indentation issue. Okay,

Okay. Oh, just indentation issue. Okay, perfect. I think rest of the stuffs are

perfect. I think rest of the stuffs are fine. Okay. And obviously we need to

fine. Okay. And obviously we need to assign the employee name because we are

assign the employee name because we are just creating this. Let's say

just creating this. Let's say Rahul let's say. Okay. Let's try to run

Rahul let's say. Okay. Let's try to run this. We simply got employee name is

this. We simply got employee name is Rahul. This was expected. But now if you

Rahul. This was expected. But now if you will try to run this function which is

will try to run this function which is company info, you cannot. Why? I will

company info, you cannot. Why? I will just tell you.

just tell you. It will simply say we do not have any

It will simply say we do not have any parameter assigned to it because when we

parameter assigned to it because when we created this class, yes, we inherited

created this class, yes, we inherited it. But we didn't mention its

it. But we didn't mention its attributes. That is why if we just want

attributes. That is why if we just want to explain classes

to explain classes without attributes and without uh you

without attributes and without uh you can say constructor, it is very easy.

can say constructor, it is very easy. But when we just want to define it with

But when we just want to define it with attributes and constructors, it is a

attributes and constructors, it is a task and I have taken the task. So it is

task and I have taken the task. So it is very easy. So basically the stuff is now

very easy. So basically the stuff is now you need to take care of the other

you need to take care of the other parameters as well. That means of your

parameters as well. That means of your parent class that means you will simply

parent class that means you will simply define it here company name. Let's say

define it here company name. Let's say company

company name. Okay. And here you will define the

name. Okay. And here you will define the self dot company name as well. Yes, you

self dot company name as well. Yes, you have to you have to make sense. Now you

have to you have to make sense. Now you will simply pass the company as well

will simply pass the company as well which is let's say

which is let's say um

um XYZ or let's say yeah

XYZ or let's say yeah XYZ. So did you get my point? Even if we

XYZ. So did you get my point? Even if we do not

do not have

have the employee name required but if we are

the employee name required but if we are inheriting the parent class if we have

inheriting the parent class if we have company name there we have to include it

company name there we have to include it in our constructor otherwise we cannot

in our constructor otherwise we cannot use their attributes. Does that make any

use their attributes. Does that make any sense? If you're inheriting it you have

sense? If you're inheriting it you have to provide the attributes right? So you

to provide the attributes right? So you have to do it. Very good. Very good. So

have to do it. Very good. Very good. So now if you just try to run this you will

now if you just try to run this you will simply see company name is XYZ

simply see company name is XYZ perfect an

perfect an Lamba we have a question simply ask is

Lamba we have a question simply ask is there any way to add this particular

there any way to add this particular function within

function within your class yes we have a function for it

your class yes we have a function for it so what's the way of doing it it's very

so what's the way of doing it it's very simple so what you will do you will

simple so what you will do you will create a normal regular function or you

create a normal regular function or you can say regular uh method you will

can say regular uh method you will simply say DF um company info. Okay. DF

simply say DF um company info. Okay. DF company info. Same name. Yes, you can

company info. Same name. Yes, you can keep the same name. And I will just show

keep the same name. And I will just show you the flow as well how it behaves. You

you the flow as well how it behaves. You will simply say self. And within this

will simply say self. And within this what you will do? You will simply call

what you will do? You will simply call the function which is this one. You can

the function which is this one. You can call the function or let's say let's

call the function or let's say let's start with the different name because

start with the different name because you will feel confused. Let's say

you will feel confused. Let's say company info child. That means it is

company info child. That means it is running from the child class or you can

running from the child class or you can say children classes. Okay. Then I will

say children classes. Okay. Then I will simply say I want to call this function.

simply say I want to call this function. Whenever I want to run this function, I

Whenever I want to run this function, I want to call this function. So how I can

want to call this function. So how I can just call this function? I will simply

just call this function? I will simply write

write um class name I guess. Yeah.

um class name I guess. Yeah. Company company dot company info. That

Company company dot company info. That means

means the function. Make sense? Make sense? So

the function. Make sense? Make sense? So now you are simply calling this function

now you are simply calling this function and there's no parameter required. So

and there's no parameter required. So you will simply run this. Now I can

you will simply run this. Now I can access this. I will simply say company

access this. I will simply say company info

info child. So what will happen? It will

child. So what will happen? It will simply give me this. And in order to

simply give me this. And in order to distinguish it, I will do one more

distinguish it, I will do one more thing. I will simply say

thing. I will simply say print this is

print this is running

running from employee. Okay. Let me run this. Oh

from employee. Okay. Let me run this. Oh wow. Error. What's wrong? What's wrong?

wow. Error. What's wrong? What's wrong? What's wrong? Um, company not

What's wrong? Um, company not encompassing one required position

encompassing one required position information. Oh, makes sense. So,

information. Oh, makes sense. So, basically it has the self, right? It has

basically it has the self, right? It has the self. So, you have to just provide

the self. So, you have to just provide the

the self. Perfect. This is running from

self. Perfect. This is running from employee and we are getting company name

employee and we are getting company name is XYZ. Wow. That means we have

is XYZ. Wow. That means we have literally called the parent function.

literally called the parent function. the function from the parent class into

the function from the parent class into the child class using this approach.

the child class using this approach. It's called company dot company info

It's called company dot company info that means employee that means basically

that means employee that means basically the class dot method simple and then

the class dot method simple and then self. You can even use something called

self. You can even use something called as super keyword. I do not recommend it.

as super keyword. I do not recommend it. Okay, you can use it if you want. Why

Okay, you can use it if you want. Why don't you recommend it? And what is this

don't you recommend it? And what is this function? Basically this particular

function? Basically this particular command is equivalent to this one. Super

command is equivalent to this one. Super keyword super

keyword super dot company

info. Okay, let me just comment it out and let me just run

and let me just run this. See same results. So what is a

this. See same results. So what is a super function? Super function means you

super function? Super function means you are actually accessing the function from

are actually accessing the function from the parent class which is just one level

the parent class which is just one level up. Which is just one level up. This is

up. Which is just one level up. This is handy when you are using single level

handy when you are using single level inheritance. This is a mess when you use

inheritance. This is a mess when you use multi-level inheritance. So why you want

multi-level inheritance. So why you want to add a mess? It is fine. You should

to add a mess? It is fine. You should know about it. But I would recommend you

know about it. But I would recommend you to stick to this approach. Which

to stick to this approach. Which one? The above one. Why? Because it will

one? The above one. Why? Because it will remain the same in multi-level in

remain the same in multi-level in multiple and in your single level as

multiple and in your single level as well. So just to make things clear, you

well. So just to make things clear, you should stick to this one. But yes, you

should stick to this one. But yes, you should know about super keyword as well.

should know about super keyword as well. Makes sense. I hope now it makes sense.

Makes sense. I hope now it makes sense. Now one real time approach. Let's say in

Now one real time approach. Let's say in this particular def

this particular def constructor I have so many attributes

constructor I have so many attributes and I do not want to pass those

and I do not want to pass those attributes because it is a

attributes because it is a task. It is literally a task. I do not

task. It is literally a task. I do not want to write self dot self dot self dot

want to write self dot self dot self dot self dot self dot I cannot let's imagine

self dot self dot I cannot let's imagine I have 100 u attributes so you can use

I have 100 u attributes so you can use this function here as well so what you

this function here as well so what you will do um we know that we have to use

will do um we know that we have to use this because this is the children or you

this because this is the children or you can say child class employee name but

can say child class employee name but for the other thing you can replace this

for the other thing you can replace this with like this company dot

with like this company dot init and then you simply can pass all

init and then you simply can pass all the variables let's say self then

the variables let's say self then obviously it needs company name right

obviously it needs company name right you will simply say company name that's

you will simply say company name that's it and from where it is getting company

it and from where it is getting company name it is getting company name from

name it is getting company name from here okay it is getting company name

here okay it is getting company name from here it will simply pick the

from here it will simply pick the company

company name oh so we can just comment it out

name oh so we can just comment it out then yes you can comment it out let's

then yes you can comment it out let's run

run this perfect it is running fine so this

this perfect it is running fine so this is another way of doing it. So that

is another way of doing it. So that means you are receiving company name.

means you are receiving company name. Okay. And within this you are passing

Okay. And within this you are passing this particular function, this

this particular function, this particular parameter here. And this way

particular parameter here. And this way you do not need to write self dot self

you do not need to write self dot self dot self dot because let's say I have

dot self dot because let's say I have one more

um attribute let's say country. Okay. And this is country name

country. Okay. And this is country name or let's say just country. Okay. So this

or let's say just country. Okay. So this is

country. Obviously I will receive the country from the object. Let's

country from the object. Let's say US let's say. So here I will simply

say US let's say. So here I will simply pass the country as well. And I need to

pass the country as well. And I need to include country in my constructor as

include country in my constructor as well. See that's how the chain works.

well. See that's how the chain works. You will see. And obviously we are not

You will see. And obviously we are not using country. So let's use it here.

using country. So let's use it here. Um company info company name is

Um company info company name is this in let's say country self dot

this in let's say country self dot country make

country make sense I hope so perfect in US very good

sense I hope so perfect in US very good this is the complex real world scenario

this is the complex real world scenario of inheritance this is the real

of inheritance this is the real inheritance okay make sense so this was

inheritance okay make sense so this was your single level inheritance Let's say

your single level inheritance Let's say you want to create multiple inheritance.

you want to create multiple inheritance. Before discussing about multi-level, we

Before discussing about multi-level, we will just talk about

will just talk about multiple multiple inheritance. So let's

multiple multiple inheritance. So let's say you have one more class. Okay, you

say you have one more class. Okay, you have one more class and this class name

have one more class and this class name is basically uh multiple inheritance

is basically uh multiple inheritance like this. Let's say you have one parent

like this. Let's say you have one parent class. It's called company.

class. It's called company. Okay. Then you have another

Okay. Then you have another um you can say parent class. And what

um you can say parent class. And what can be the parent

can be the parent class? Uh let's say department. Yep.

class? Uh let's say department. Yep. Department. No, department is not a good

Department. No, department is not a good example.

example. [Music]

[Music] Um let's say we

Um let's say we have

have class equals to region. Let's

class equals to region. Let's say region or let's say country. Let's

say region or let's say country. Let's create a separate one for country. Okay,

create a separate one for country. Okay, we have country. So the this is my

we have country. So the this is my parent class one. This is my parent

parent class one. This is my parent class two. Now I am creating my child

class two. Now I am creating my child class which is called employee. Now

class which is called employee. Now within this class I need

within this class I need to add this as my

to add this as my parent

parent and this as my parent as well. So now

and this as my parent as well. So now there are two parents. Make sense? There

there are two parents. Make sense? There are two parents. And this is very

are two parents. And this is very simple. This is very simple because now

simple. This is very simple because now you have a strong base ready. You can

you have a strong base ready. You can just use anything. So now let's say you

just use anything. So now let's say you have a class called country.

Okay. And let's remove country from here just to make it simple. Okay. Perfect.

just to make it simple. Okay. Perfect. Perfect.

Perfect. And perfect. And let's remove country

And perfect. And let's remove country from here because we'll be using it with

from here because we'll be using it with the different parent. Perfect. And

the different parent. Perfect. And there's no need to pass it here.

there's no need to pass it here. Perfect. And let me just check like

Perfect. And let me just check like everything is running fine because we

everything is running fine because we removed some stuff. Oops. Something is

removed some stuff. Oops. Something is missing.

missing. Um. Oh yeah, we need to remove it from

Um. Oh yeah, we need to remove it from here as well. Perfect. Now I think it

here as well. Perfect. Now I think it should be good. Perfect. Yes. Now let's

should be good. Perfect. Yes. Now let's create a new class. It's called

create a new class. It's called country, right?

country, right? So we will have a

So we will have a constructor df in it and then self and

constructor df in it and then self and this will be let's say country name or

this will be let's say country name or let's say just country or let's say

let's say just country or let's say country name. I will simply say self

country name. I will simply say self dot country

dot country name equals to country name. Okay, this

name equals to country name. Okay, this is simple. This is simple stuff. And

is simple. This is simple stuff. And within this we have def country info.

within this we have def country info. Okay, makes sense. I'll simply say self

Okay, makes sense. I'll simply say self and I will simply

print country name is self dot country name. Make sense? Very good.

dot country name. Make sense? Very good. So this is my second class. Now I want

So this is my second class. Now I want to include this class as well in my

to include this class as well in my employee class. Very simple. You simply

employee class. Very simple. You simply need to write country. That's it. This

need to write country. That's it. This is an edited. Wow. But just to check

is an edited. Wow. But just to check your fundamentals, what do we need to do

your fundamentals, what do we need to do next? What we need to include the

next? What we need to include the attributes of this class as well in

attributes of this class as well in order to use it. In order to use it,

order to use it. In order to use it, very good. And how we can do that? We

very good. And how we can do that? We will simply say, and what is a better

will simply say, and what is a better way of doing it? Basically, what's the

way of doing it? Basically, what's the better of way of doing it?

better of way of doing it? uh the better way of doing it

uh the better way of doing it is using this method company do this. So

is using this method company do this. So this way first of all we need to get the

this way first of all we need to get the value from the user for the country I

value from the user for the country I will simply say country name. Okay then

will simply say country name. Okay then I will call the second parent

I will call the second parent class it the name is country I guess.

class it the name is country I guess. Yeah, country

Yeah, country dot init and then self and country name.

dot init and then self and country name. Now you should actually feel why super

Now you should actually feel why super keyword is not actually handy. If I

keyword is not actually handy. If I would use super keyword here, it would

would use super keyword here, it would be confused. Should I just make a call

be confused. Should I just make a call on this one or this one? Ideally, it is

on this one or this one? Ideally, it is not confused. It will always give

not confused. It will always give priority to the first added parent. But

priority to the first added parent. But it doesn't make any sense. It creates

it doesn't make any sense. It creates confusion when you read code, right? So

confusion when you read code, right? So this is the best way to use

this is the best way to use the class name whenever you want to just

the class name whenever you want to just make a call. Okay, very good. So this is

make a call. Okay, very good. So this is also done. This will bring all the

also done. This will bring all the attribute. This will bring all the

attribute. This will bring all the attributes. Let's say we want to create

attributes. Let's say we want to create a nice info function. Let's recreate

a nice info function. Let's recreate this

this function. Let's create it like this def

function. Let's create it like this def full info. Okay, this is very special

full info. Okay, this is very special because what we will do? We will simply

because what we will do? We will simply say the

employee and then employee name which is self dot

Okay. Employee name lives

name lives in self dot country name.

in self dot country name. Oh, so we are actually

Oh, so we are actually accessing this keyword this basically

accessing this keyword this basically attribute as well. And how? Because now

attribute as well. And how? Because now this attribute is the part of this class

this attribute is the part of this class employee as well because this is

employee as well because this is inherited using the parent class. Plus

inherited using the parent class. Plus we have also assigned the attribute

we have also assigned the attribute within this class as well. So that we

within this class as well. So that we can actually inherit and use all the

can actually inherit and use all the things. Very good. Now you are getting

things. Very good. Now you are getting all the things. Very good. lives in

all the things. Very good. lives in country

country and works

and works for self dot company name. Company name

for self dot company name. Company name or com com name I guess com name. Yeah,

or com com name I guess com name. Yeah, com

com name. Makes sense. Very good.

name. Makes sense. Very good. Now let's maybe you can say add another

Now let's maybe you can say add another function here. Okay, let me say country

function here. Okay, let me say country dot country info. Let's call this

dot country info. Let's call this function as

function as well. Perfect. Our class is ready.

well. Perfect. Our class is ready. Multiple classes ready. Just to show

Multiple classes ready. Just to show you, this is our parent class one. This

you, this is our parent class one. This is our parent class two.

is our parent class two. Okay. This is parent

Okay. This is parent one. This

one. This is parent two. And this is our child

is parent two. And this is our child class which is inheriting both the

class which is inheriting both the class. Make sense? Very good. Let's

class. Make sense? Very good. Let's actually try to run it. Okay. Okay. And

actually try to run it. Okay. Okay. And obviously we need to just give us as

obviously we need to just give us as well here. And first of all we simply

well here. And first of all we simply run this just to see the errors.

run this just to see the errors. Um it is saying self dot country name

Um it is saying self dot country name equals to country name. Where? Where?

equals to country name. Where? Where? Where? Where? Oh we added a space. No

Where? Where? Oh we added a space. No worries. Perfect. This code is fine.

worries. Perfect. This code is fine. This code is fine. Let's try

This code is fine. Let's try to run this. I want to run emp1 dot full

to run this. I want to run emp1 dot full info. Okay, let's see.

info. Okay, let's see. Wow, very good. Very very very good. Now

Wow, very good. Very very very good. Now I want to run

I want to run empfo child. Basically not company info.

empfo child. Basically not company info. This is like your all info. Let's say

This is like your all info. Let's say all info.

all info. Okay. All info child because this is

Okay. All info child because this is running from the child. Very good. So,

running from the child. Very good. So, so, so good. This is your multiple

so, so good. This is your multiple inheritance. Bang on. Very good. Now,

inheritance. Bang on. Very good. Now, finally, let's talk about multilevel

finally, let's talk about multilevel inheritance. So, basically, it should be

inheritance. So, basically, it should be clear to you, I think, because you are

clear to you, I think, because you are already wellversed with inheritance. So,

already wellversed with inheritance. So, let's say this is your company class.

let's say this is your company class. Okay, this is your company class and

Okay, this is your company class and then you have a class called department

then you have a class called department because within company we have

because within company we have departments. Okay, so this will simply

departments. Okay, so this will simply inherit this company class as well here

inherit this company class as well here like this. Then you have an employee

like this. Then you have an employee class. Let's say an employee class. So

class. Let's say an employee class. So here this time you will simply

here this time you will simply Oops. Oh man. Oh man. Let me just

Oops. Oh man. Oh man. Let me just redraw. Hm. So basically let's say this

redraw. Hm. So basically let's say this is your employee class uh sorry company

is your employee class uh sorry company class.

class. Okay very good. Then you have department

Okay very good. Then you have department class

class with company class inherited. So far

with company class inherited. So far this is just single level. Now it

this is just single level. Now it becomes multi-level

becomes multi-level because it will

because it will simply be inherited by employee as well.

simply be inherited by employee as well. Now when employee will inherit this

Now when employee will inherit this department class, it will automatically

department class, it will automatically inherit this company class as well. Wow,

inherit this company class as well. Wow, this is multi-level. This is

this is multi-level. This is multi-level. And don't worry, this is

multi-level. And don't worry, this is also very simple. Very simple. Let me

also very simple. Very simple. Let me just try to explain you how it will work

just try to explain you how it will work and how you need to work with uh

and how you need to work with uh decorators, not decorators, basically

decorators, not decorators, basically constructors because that is the most

constructors because that is the most crucial thing. So let's say this is our

crucial thing. So let's say this is our company class. This is fine. Okay. And

company class. This is fine. Okay. And for now just forget about this employee

for now just forget about this employee class. Let's first create the department

class. Let's first create the department class

class department. Okay. And within this we

department. Okay. And within this we have

df init in it and let's say

it and let's say self and department name.

self and department name. Okay. Very good. I will simply say cell

Okay. Very good. I will simply say cell dot department name

dot department name equals department

equals department name. Make

name. Make sense? Okay, very good. This is the

sense? Okay, very good. This is the simple thing. And let's create a normal

simple thing. And let's create a normal function for company

function for company name. Uh not company, department

name. Uh not company, department info. Department info. Okay, very good.

info. Department info. Okay, very good. self it will simply say

self it will simply say print the

print the department

department info

info is let's say department name self dot

is let's say department name self dot department

name okay very good make sense will it work the answer is no why because we are

work the answer is no why because we are not inheriting all the things from here

not inheriting all the things from here that means if I inher inherited this

that means if I inher inherited this department class. I will not be able to

department class. I will not be able to access company class because I'm not

access company class because I'm not inheriting all the things within this

inheriting all the things within this department class. So it's my duty to

department class. So it's my duty to inherit all the things that is company

inherit all the things that is company name. Okay. And now I need to call this

name. Okay. And now I need to call this company function as well. So company

company function as well. So company dot init. Okay. And within the self then

dot init. Okay. And within the self then company name. Make sense? Now I'm good.

company name. Make sense? Now I'm good. Now I'm good. I can even show you let's

Now I'm good. I can even show you let's say department name or let's say oh yeah

say department name or let's say oh yeah this is very good. Let's let's try this.

this is very good. Let's let's try this. This is very good. Let's say I'm

This is very good. Let's say I'm creating a function called info. Okay

creating a function called info. Okay department info. Okay department info.

department info. Okay department info. So it will simply say department is this

So it will simply say department is this one

uh com name I guess uh self.com self do comn

self.com self do comn name perfect so this is my function and

name perfect so this is my function and it is already using this value because

it is already using this value because of inheritance now we will simply

of inheritance now we will simply inherit

inherit Perfect. This is done. Now I will simply

Perfect. This is done. Now I will simply use employee class and I will inherit

use employee class and I will inherit department.

department. Wow. I will simply inherit department.

Wow. I will simply inherit department. Very good. This time this time what I

Very good. This time this time what I need to do here I will simply say

need to do here I will simply say employee name. Obviously for employee I

employee name. Obviously for employee I will simply say department

will simply say department name.

name. Okay. And then I will simply say company

Okay. And then I will simply say company name or you can say com name. Make

name or you can say com name. Make sense? So this is fine. Self dot this.

sense? So this is fine. Self dot this. Now what this is the trickiest part. Now

Now what this is the trickiest part. Now I simply need to call this function

I simply need to call this function only. That's it. Why? Because this will

only. That's it. Why? Because this will automatically call this function. See it

automatically call this function. See it is already inherited. It is already

is already inherited. It is already inherited.

inherited. But but you need to make sure that you

But but you need to make sure that you provide all the parameters here. Make

provide all the parameters here. Make sense? So I will simply say

sense? So I will simply say department dot

department dot init

init okay self and department name is your

okay self and department name is your department

department name and then company name is

name and then company name is your company name. You can even write

your company name. You can even write something like this. Okay. So this will

something like this. Okay. So this will pass this will go to this will go to

pass this will go to this will go to here automatically. Okay. Then once it

here automatically. Okay. Then once it is done that means we have access to all

is done that means we have access to all the parameters. Let's create something

the parameters. Let's create something called like this which is

info. Okay. And we need to write it like this. Indentation is important. Very

this. Indentation is important. Very good. This is my all

good. This is my all info. Now let's see if we are able to

info. Now let's see if we are able to pull this information. Okay. And we'll

pull this information. Okay. And we'll simply

simply say

employee name is self dot emp name. This will be fun.

is self dot emp name. This will be fun. Let's test it. Let's let me remove all

Let's test it. Let's let me remove all the other code.

the other code. Okay, let me remove all the other

Okay, let me remove all the other code. So now now is the thing. Let's

code. So now now is the thing. Let's test it. Let's say this is my object.

test it. Let's say this is my object. Okay, this is my object. Rahul

Okay, this is my object. Rahul department is let's say HR and the

department is let's say HR and the country um not country uh company

country um not country uh company company is let's say ABC okay let's see

company is let's say ABC okay let's see if we have any errors no errors wow I

if we have any errors no errors wow I will simply say emp1 dot all

will simply say emp1 dot all info let's see what happens perfect man

info let's see what happens perfect man perfect department is HR ABC Rahul let

perfect department is HR ABC Rahul let me try to call department info let's see

me try to call department info let's see What

happens? Very good. So what will happen here? It will simply call department

here? It will simply call department info. Okay. Here it will simply call

info. Okay. Here it will simply call department info. And obviously this

department info. And obviously this object is for employee class. See this

object is for employee class. See this object is for employee class. But this

object is for employee class. But this function is inherited because we

function is inherited because we inherited department class. Makes sense.

inherited department class. Makes sense. and all the parameters that it needs

and all the parameters that it needs such as department name, com name, we

such as department name, com name, we already inherited it here as well. See,

already inherited it here as well. See, now is the fun part. Can we call this

now is the fun part. Can we call this function company info? Yes, let's test

function company info? Yes, let's test it. Okay, let's call this

function. Perfect. Yes, we can do that because this particular

because this particular object, let's this particular object is

object, let's this particular object is of this class. We are calling this

of this class. We are calling this function because this function is part

function because this function is part of this department class and this

of this department class and this department class in is inherited here

department class in is inherited here and

and whatever attributes it needs like com

whatever attributes it needs like com name we are already passing it in the

name we are already passing it in the department name. That's why it is

department name. That's why it is important to pass all the attributes

important to pass all the attributes every time. Every time. Every time.

every time. Every time. Every time. Every time. Wow. Let me just show you

Every time. Wow. Let me just show you something else. Let's say there's a

something else. Let's say there's a scenario where we have the function with

scenario where we have the function with same name in all the classes parent to

same name in all the classes parent to children whatever. So in this particular

children whatever. So in this particular scenario let me just show you what will

scenario let me just show you what will happen. Let's say we have a function

happen. Let's say we have a function called def um show

called def um show me. Okay. And this does nothing. This

me. Okay. And this does nothing. This will simply

will simply say I am grandfather. Okay. Because this

say I am grandfather. Okay. Because this is like child's father's father. So G

is like child's father's father. So G grandfather

grandfather okay it has same function it's called

okay it has same function it's called show me which same name okay same name

show me which same name okay same name it will simply

it will simply say I am

say I am father okay and here as well it will be

father okay and here as well it will be having a function called show me it will

having a function called show me it will simply

say I am a pro okay now Now if I call this function

this function emp1 dot show me which function will be

emp1 dot show me which function will be called just tell me in the comments

called just tell me in the comments right now with a heart with a lovely

right now with a heart with a lovely heart. So it will simply call this

heart. So it will simply call this function. You can see it. See why?

function. You can see it. See why? Because it takes the priority over its

Because it takes the priority over its inherited classes.

inherited classes. Okay, this makes sense because this is a

Okay, this makes sense because this is a local function and obviously local

local function and obviously local things get priority. Let's say I don't

things get priority. Let's say I don't even have any function like this. Now I

even have any function like this. Now I have the same function in the department

have the same function in the department and in the show me as well. Now what

and in the show me as well. Now what will happen?

will happen? Okay, it will simply say I am a father.

Okay, it will simply say I am a father. Okay, why? Because the second parent

Okay, why? Because the second parent will take the priority. Okay. Now if we

will take the priority. Okay. Now if we do not have a function here as well then

do not have a function here as well then only it will say I'm grandfather. Okay.

only it will say I'm grandfather. Okay. Make sense? Very good. So this is your

Make sense? Very good. So this is your multi-level

multi-level inheritance. I hope now you know all the

inheritance. I hope now you know all the things in inheritance. I hope that this

things in inheritance. I hope that this session was really really helpful for

session was really really helpful for inheritance especially because I

inheritance especially because I genuinely written so many things that I

genuinely written so many things that I will explain this I will explain that.

will explain this I will explain that. Let me just check that I covered all the

Let me just check that I covered all the things because I want you to know all

things because I want you to know all the things and just to mention all the

the things and just to mention all the things like let's say super keyword

things like let's say super keyword those functions calling and all the

those functions calling and all the things and I hope we did it very well.

things and I hope we did it very well. Wow. Wow. Wow. Wow. Multi level is also

Wow. Wow. Wow. Wow. Multi level is also done. Okay. Makes sense. Okay. Now we

done. Okay. Makes sense. Okay. Now we can say that yeah it was a good one

can say that yeah it was a good one because this is really important this

because this is really important this particular session like inheritance is

particular session like inheritance is really really important. Make sense?

really really important. Make sense? Okay. Now we going to cover something

Okay. Now we going to cover something called as multi-threading. What is

called as multi-threading. What is multi-threading?

multi-threading? Multi-threading is the most powerful

Multi-threading is the most powerful thing that you can learn right now

thing that you can learn right now because this goes really really well

because this goes really really well with data engineering development and

with data engineering development and you will get to know why it is so much

you will get to know why it is so much powerful because I will just show you

powerful because I will just show you the examples as well. Okay, let's master

the examples as well. Okay, let's master multi-threading and after

multi-threading and after multi-threading we going to cover some

multi-threading we going to cover some amazing modules in Python such as

amazing modules in Python such as request method to work with APIs. We

request method to work with APIs. We also going to work like we we will see a

also going to work like we we will see a lot of stuff like small small stuff that

lot of stuff like small small stuff that are like really really handy. Let me

are like really really handy. Let me just show you. Let's talk about

just show you. Let's talk about multi-threading. What is

multi-threading. What is multi-threading? What is

multi-threading? What is multi-threading? Basically, let's say

multi-threading? Basically, let's say you have your program. Let's say you

you have your program. Let's say you have a function. Okay, you have a

have a function. Okay, you have a function. Okay, now you want to run this

function. Okay, now you want to run this function multiple times. Let's say you

function multiple times. Let's say you want to run your function 10 times. You

want to run your function 10 times. You will simply say, hey, now I'm a pro. I

will simply say, hey, now I'm a pro. I know how to use loop. So I can simply

know how to use loop. So I can simply use a loop for loop and I can simply run

use a loop for loop and I can simply run this

this function through a loop. Yes, you are

function through a loop. Yes, you are right. But the issue is that loop will

right. But the issue is that loop will run in sequence. That means that loop

run in sequence. That means that loop will first complete your first iteration

will first complete your first iteration then it will go to the second then it

then it will go to the second then it will go to the third then it will go to

will go to the third then it will go to the fourth then so on till 10th. Yeah.

the fourth then so on till 10th. Yeah. So what's wrong with this? Nothing is

So what's wrong with this? Nothing is wrong in this. But what if you want to

wrong in this. But what if you want to process all the 10 iterations

process all the 10 iterations together parallelly? Yes, parallelly.

together parallelly? Yes, parallelly. What if you want to do something like

What if you want to do something like this? That's where multi-threading comes

this? That's where multi-threading comes into the picture. It actually creates

multi-threads so that you can process your data

your data simultaneously. So you can actually run

simultaneously. So you can actually run your data or let's say um let's not talk

your data or let's say um let's not talk about data like normally you can just

about data like normally you can just run your program parallelly. You do not

run your program parallelly. You do not need to wait for the previous one to

need to wait for the previous one to complete and then start the second one.

complete and then start the second one. This is the power of

This is the power of multi-threading. A good example in data

multi-threading. A good example in data engineing domain let's say you are just

engineing domain let's say you are just writing your spark application. Okay.

writing your spark application. Okay. Now you want to let's say you are just

Now you want to let's say you are just building a datab bricks notebook. Okay.

building a datab bricks notebook. Okay. in which you're writing your pispar

in which you're writing your pispar code, you want to perform the same

code, you want to perform the same things, all the same things for

things, all the same things for different different tables, all the same

different different tables, all the same things. So if you just want to let's say

things. So if you just want to let's say run it through loop. So first your first

run it through loop. So first your first data will be loaded then second then

data will be loaded then second then third then fourth let's say you have 100

third then fourth let's say you have 100 tables you'll be just waiting for your

tables you'll be just waiting for your all the 99 tables to be completed to

all the 99 tables to be completed to just complete the last one. What if I

just complete the last one. What if I say just run all the applications

say just run all the applications together? So just imagine the

together? So just imagine the speed almost 100 times faster right

speed almost 100 times faster right that's where multi-threading comes into

that's where multi-threading comes into the picture and it becomes really really

the picture and it becomes really really handy for data engineers. So now it's

handy for data engineers. So now it's time to look at the code so that you can

time to look at the code so that you can actually understand what we are going to

actually understand what we are going to do. So let me clear all these

do. So let me clear all these inheritance and all. Okay let's talk

inheritance and all. Okay let's talk about multi-threading. Okay makes sense.

about multi-threading. Okay makes sense. So basically let's create a function and

So basically let's create a function and even before creating a function we need

even before creating a function we need to import some modules just to show you

to import some modules just to show you the results. So I will simply import

the results. So I will simply import times. I will import um

uh random and then I need to import from

random and then I need to import from futures dotconcurrent I

guess. import thread pool

exeutor. Okay let's run this. Let's see if all the modules are right. No named

if all the modules are right. No named No module named called futures. Maybe

No module named called futures. Maybe from

from future. No module named called future.

future. No module named called future. Wow. So I think let me just see what is

Wow. So I think let me just see what is the exact module

name concurrent. Futures not future.concurrent. Okay. From

concurrent.futures import threadpool executor. Make sense? Now we are good to

executor. Make sense? Now we are good to go. Let's say first of all I will just

go. Let's say first of all I will just show you the traditional approach that

show you the traditional approach that you do without thread pool executor or

you do without thread pool executor or let's say without multi-threading.

let's say without multi-threading. Threadpool exeutor is the module that is

Threadpool exeutor is the module that is the best if you just want to perform

the best if you just want to perform multi-threading. Okay, there are many

multi-threading. Okay, there are many but this is the best one. So let's say

but this is the best one. So let's say you have a function df my function.

you have a function df my function. Okay. Then within this function

Okay. Then within this function obviously takes a parameter let's say

obviously takes a parameter let's say px.

px. Okay. Px. Okay. What it does? It will

Okay. Px. Okay. What it does? It will basically print

basically print um I am px just to see like what value

um I am px just to see like what value it is getting. Okay. I am

it is getting. Okay. I am px I

px I took how many seconds? I will just talk

took how many seconds? I will just talk about this. So basically we going to use

about this. So basically we going to use something called as time function

something called as time function because we will be using something

because we will be using something called as time dots

called as time dots sleep okay because we this function is

sleep okay because we this function is so quick that it will not actually show

so quick that it will not actually show you the difference. So that you can

you the difference. So that you can actually see the difference we will

actually see the difference we will simply use time dots sleep method and

simply use time dots sleep method and what we can just use in sleep method you

what we can just use in sleep method you can simply say 2 seconds 4 seconds 3

can simply say 2 seconds 4 seconds 3 seconds. So this is a very good module

seconds. So this is a very good module that you can just discover. You can

that you can just discover. You can simply say time module or let's say time

simply say time module or let's say time dot

sleep time do sleep method and in which you can simply say time dots sleep if

you can simply say time dots sleep if you just want your system or let's say

you just want your system or let's say program to sleep for 6 seconds you can

program to sleep for 6 seconds you can simply say time do sleep 6 that's it so

simply say time do sleep 6 that's it so now I don't want to give the fixed value

now I don't want to give the fixed value no I want to give random value I will

no I want to give random value I will simply say random

simply say random dotrandant and I will simply pick random

dotrandant and I will simply pick random value between 1 to 10. Okay, this is the

value between 1 to 10. Okay, this is the function that we use to provide random

function that we use to provide random value. Make sense? Very good. This is

value. Make sense? Very good. This is the function. That's it. If I want to

the function. That's it. If I want to run this function, okay, I will simply

run this function, okay, I will simply call

call it my function. Okay, and then I will

it my function. Okay, and then I will simply say let's say um 101. Okay, what

simply say let's say um 101. Okay, what it will do? It will throw an error. Uh

it will do? It will throw an error. Uh oh, it's

oh, it's rand. I just did a typo. So IM101 I

rand. I just did a typo. So IM101 I took I need to just write this as well.

took I need to just write this as well. I will simply make a variable called

I will simply make a variable called weight. I

weight. I took weight

seconds. Make sense? So why it is taking now long? Because it is performing sleep

now long? Because it is performing sleep operation. Okay. Let me just run for one

operation. Okay. Let me just run for one more time.

Okay. So what is happening here? It is simply performing some sleep. But if I

simply performing some sleep. But if I just want to get the value of sleep, if

just want to get the value of sleep, if I just want to see like how long it

I just want to see like how long it took, I need to just use something else

took, I need to just use something else so that I can show you how long it is

so that I can show you how long it is taking. So for that what you can do, you

taking. So for that what you can do, you can simply I will first store this value

can simply I will first store this value in the variable. Okay, like this.

in the variable. Okay, like this. Okay, then I will pass this value here

Okay, then I will pass this value here which is

which is weight because this way I can even store

weight because this way I can even store this value here. Let me just run this so

this value here. Let me just run this so you will actually see how long it is

you will actually see how long it is taking to sleep. So this time it is it

taking to sleep. So this time it is it took 5 seconds.

took 5 seconds. Okay, let me run it again. So this time

Okay, let me run it again. So this time it took 2 seconds. So basically what is

it took 2 seconds. So basically what is the purpose of this? Let's say you are

the purpose of this? Let's say you are processing your data. Okay, sometimes

processing your data. Okay, sometimes your data can take 5 seconds.

your data can take 5 seconds. Second table is taking 2 seconds. Third

Second table is taking 2 seconds. Third table is taking 10 seconds. Fourth table

table is taking 10 seconds. Fourth table is taking let's say 6 seconds. So this

is taking let's say 6 seconds. So this way every table's data size will be

way every table's data size will be different. Right? So I am just creating

different. Right? So I am just creating that environment so that you can

that environment so that you can actually feel that you are processing

actually feel that you are processing the data. Okay, make sense? Very good.

the data. Okay, make sense? Very good. Now let me just give you the table

Now let me just give you the table names. Okay, let's create a list. I will

names. Okay, let's create a list. I will simply say tables and let's create let's

simply say tables and let's create let's say

say orders

orders products okay

products okay customers then um let's say uh reviews

customers then um let's say uh reviews and then one more let's say

and then one more let's say cancellations or cancels okay make sense

cancellations or cancels okay make sense now if I want to process my data without

now if I want to process my data without multi-threading what I will do I will

multi-threading what I will do I will simply say for i in tables

simply say for i in tables Okay.

Okay. Then simply

Then simply oops. What is

oops. What is this? Yeah. So simply pass this

this? Yeah. So simply pass this particular parameter through loop.

particular parameter through loop. Through loop. So now what will happen?

Through loop. So now what will happen? Let me just show you what will happen.

Let me just show you what will happen. This time we need to simply run this

This time we need to simply run this function through a loop. Okay. So how we

function through a loop. Okay. So how we can just do that? Obviously first we

can just do that? Obviously first we need to define this function outside the

need to define this function outside the loop like this. Okay, like this. And

loop like this. Okay, like this. And simply we'll call this function one by

simply we'll call this function one by one. Okay, we'll simply say uh my

one. Okay, we'll simply say uh my function

function and one time it will take orders then

and one time it will take orders then products then customers then reviews can

products then customers then reviews can then cancels. Make sure that you are

then cancels. Make sure that you are having that wipe that in the real world

having that wipe that in the real world you will be having hundreds of tables.

you will be having hundreds of tables. Okay, very good. Now let's run this. Now

Okay, very good. Now let's run this. Now let's see what will happen. We do not

let's see what will happen. We do not know which table will process first.

know which table will process first. Okay, obviously it will be orders. But

Okay, obviously it will be orders. But yeah, I'm just telling you. So px is not

yeah, I'm just telling you. So px is not defined. Obviously this is not px. This

defined. Obviously this is not px. This is

is I. Okay, so now we are not using

I. Okay, so now we are not using multi-threading. What it will do? It

multi-threading. What it will do? It will simply first of all process orders.

will simply first of all process orders. It can take any much time. Then

It can take any much time. Then products, then customers. Oh sorry,

products, then customers. Oh sorry, orders, products, customers, reviews,

orders, products, customers, reviews, cancels. Let's run this. And it depends

cancels. Let's run this. And it depends upon the data size. Okay. Orders table

upon the data size. Okay. Orders table took 3 seconds. Now let's next table

took 3 seconds. Now let's next table took 3 seconds. Wow. Next table it

took 3 seconds. Wow. Next table it took it

took it took 8 seconds. Wow. Next

took 8 seconds. Wow. Next table it

took quick. It took 10 seconds. Wo. Now the

quick. It took 10 seconds. Wo. Now the last table

last table cancels

took 8 seconds. Perfect. So did you see what is the issue? Let's say I have

what is the issue? Let's say I have hundreds of tables. I need to wait for

hundreds of tables. I need to wait for first table to to complete then second

first table to to complete then second then third then fourth. I do not want to

then third then fourth. I do not want to do that. I cannot do that. It is not

do that. I cannot do that. It is not ideal. So instead what I want to do I

ideal. So instead what I want to do I want to process all the tables together

want to process all the tables together in parallel. Now what I will do this is

in parallel. Now what I will do this is my function. Okay this will be remaining

my function. Okay this will be remaining the same. This will remain the same. I

the same. This will remain the same. I will remove this loop because I do not

will remove this loop because I do not need loop. Loops are slow. We will use

need loop. Loops are slow. We will use multi-threading. How we can just use

multi-threading. How we can just use multi- threading? So we will use

multi- threading? So we will use something called as

something called as with thread pool executor. Okay. with

with thread pool executor. Okay. with thread pool executor. Now you need to

thread pool executor. Now you need to say maximum

say maximum executors. Let me just see the syntax so

executors. Let me just see the syntax so that I do not make any mistake. Um yeah

that I do not make any mistake. Um yeah so max

so max workers now this is critical max workers

workers now this is critical max workers you need to pick as per the length of

you need to pick as per the length of this particular list. Okay you can

this particular list. Okay you can simply say length of tables. Why?

simply say length of tables. Why? Because you

Because you need all the workers to working on the

need all the workers to working on the individual item, right? So this will

individual item, right? So this will basically create the workers for you. It

basically create the workers for you. It will create workers. How many workers do

will create workers. How many workers do you need? Simple. The number of tables

you need? Simple. The number of tables that you have so that you can

that you have so that you can individually individually run that and

individually individually run that and all will be running parallelly. Okay. So

all will be running parallelly. Okay. So max workers as this and then you can

max workers as this and then you can simply let me check the braces. Max

simply let me check the braces. Max workers this uh this as

workers this uh this as executor as executor if I am right. Yeah

executor as executor if I am right. Yeah perfect. So now you have created the

perfect. So now you have created the executors equals to five because we have

executors equals to five because we have five tables. If you have 100 it will it

five tables. If you have 100 it will it will create 100. Now what we need to do

will create 100. Now what we need to do we will simply create futures. We will

we will simply create futures. We will simply create futures.

simply create futures. futures equals executor dot map dot map

futures equals executor dot map dot map it will simply

it will simply create future for each exeutor and it

create future for each exeutor and it will simply map it map on what first we

will simply map it map on what first we need to define the function what it

need to define the function what it needs to perform it needs to perform my

needs to perform it needs to perform my function and what is the list or array

function and what is the list or array on which it needs to perform the

on which it needs to perform the iteration it needs to perform the

iteration it needs to perform the iteration on tables that's it. That's

iteration on tables that's it. That's it. The moment you run this, you will

it. The moment you run this, you will actually

actually see it is running. Okay, I am customers.

see it is running. Okay, I am customers. I took 1 seconds. Now everything is

I took 1 seconds. Now everything is running parallelly. Okay, I am products.

running parallelly. Okay, I am products. See orders and cancels took same time.

See orders and cancels took same time. So it just ran instantly. So can you see

So it just ran instantly. So can you see that it actually ran parallelly? It

that it actually ran parallelly? It actually ran parallelly because these

actually ran parallelly because these two things actually appeared

two things actually appeared immediately. That means it didn't wait

immediately. That means it didn't wait for it to complete. It didn't wait for

for it to complete. It didn't wait for it to complete. It immediately brought

it to complete. It immediately brought it. It immediately brought it. Make

it. It immediately brought it. Make sense? And even if you do not trust me,

sense? And even if you do not trust me, let me just put um let me just comment

let me just put um let me just comment it out and let me just put let's say 3

it out and let me just put let's say 3 seconds. You will see that all the

seconds. You will see that all the things will be done immediately at once.

things will be done immediately at once. See done. And obviously in order to see

See done. And obviously in order to see this I can simply say

this I can simply say uh time dot

uh time dot sleep three

sleep three and I

and I took let's say weight equals yeah let me

took let's say weight equals yeah let me put here weight equals to three perfect

put here weight equals to three perfect let me just show

you see it ran parallelly it didn't wait for

see it ran parallelly it didn't wait for it to complete then this then this then

it to complete then this then this then this then this all took 3 seconds and

this then this all took 3 seconds and together boom this is the power of

together boom this is the power of thread pool executor there is another

thread pool executor there is another way to run this okay just to make you

way to run this okay just to make you aware there's another way to run this

aware there's another way to run this what we can do we can even run a loop

what we can do we can even run a loop you will say hey why we are running a

you will say hey why we are running a loop basically you are not actually

loop basically you are not actually running a loop to run the things in

running a loop to run the things in series you are running the loop in

series you are running the loop in parallel so when you say for i in

parallel so when you say for i in um first you will simply say

futures not futures basically simply write for I in tables make sense then

write for I in tables make sense then you will simply use something called as

you will simply use something called as future equals executor dot

future equals executor dot subummit now what you need to submit

subummit now what you need to submit obviously the function the function name

obviously the function the function name is my function and what's the value you

is my function and what's the value you are submitting you are submitting I that

are submitting you are submitting I that means only one table. So basically what

means only one table. So basically what this loop will do just try to understand

this loop will do just try to understand this loop will submit first of all this

this loop will submit first of all this value which is which is orders but it

value which is which is orders but it will not wait for it to complete it will

will not wait for it to complete it will immediately go to products it will

immediately go to products it will simply pass this it will not wait for it

simply pass this it will not wait for it to complete it will simply give

to complete it will simply give customers then reviews then cancels. So

customers then reviews then cancels. So it is not your traditional loop for

it is not your traditional loop for loop. It will simply use a loop to give

loop. It will simply use a loop to give the value to this I only once it has

the value to this I only once it has given the value done. Second value done.

given the value done. Second value done. Third value done. Fourth value done.

Third value done. Fourth value done. Fifth value

Fifth value done. Make sense? Make sense? So this is

done. Make sense? Make sense? So this is like this is again like subjective to

like this is again like subjective to developers. I personally use map method

developers. I personally use map method because I like that some developers use

because I like that some developers use submit method. So it's up to you if you

submit method. So it's up to you if you just want to use submit method. Submit

just want to use submit method. Submit method is used to create future

method is used to create future individually. But map method will create

individually. But map method will create all the futures simultaneously like in

all the futures simultaneously like in parallel. Okay, this will also give you

parallel. Okay, this will also give you the same results. Let me just run this.

the same results. Let me just run this. Uh my function is not defined. Oh my

Uh my function is not defined. Oh my funk not

funk not function. So it will give you same

function. So it will give you same results which is boom 3 seconds. So this

results which is boom 3 seconds. So this is the another way to do that. This

is the another way to do that. This doesn't mean that okay it will first run

doesn't mean that okay it will first run the loop so that means it will first

the loop so that means it will first create the future and then it will wait

create the future and then it will wait for it to get completed. No it's its

for it to get completed. No it's its only task is to assign this variable I

only task is to assign this variable I once it is done it is done. Let me just

once it is done it is done. Let me just show you graphically. So what will

show you graphically. So what will happen? Um first of all it will get the

happen? Um first of all it will get the future equals to orders. So it will

future equals to orders. So it will simply provide

simply provide orders. Okay done. It will be released.

orders. Okay done. It will be released. It will be released for processing

It will be released for processing immediately. It will give

immediately. It will give products. It provided that that value it

products. It provided that that value it will be released into a thread. That

will be released into a thread. That means similar to all the values. So it

means similar to all the values. So it will be released like one by one one by

will be released like one by one one by one by one by one. It do not need to

one by one by one. It do not need to wait to get it completed. Make sense?

wait to get it completed. Make sense? This is your multi-threading. I know it

This is your multi-threading. I know it is a little complex but just try to

is a little complex but just try to rewatch this part because this is

rewatch this part because this is something new. It is not complex. This

something new. It is not complex. This is something new. when I was learning

is something new. when I was learning about this, this was new. I tried it. I

about this, this was new. I tried it. I just played with it and literally you

just played with it and literally you will fall in love with this as a data

will fall in love with this as a data engineer. Okay, so just focus on these

engineer. Okay, so just focus on these things. These are really really

things. These are really really important. And now let's actually master

important. And now let's actually master some of the modules that we have

some of the modules that we have something called as request module

something called as request module because being a data engineer you will

because being a data engineer you will be making a lot of API calls. So let me

be making a lot of API calls. So let me just give you a strong understanding of

just give you a strong understanding of request module within Python. Let me

request module within Python. Let me just tell you. So let's try to master

just tell you. So let's try to master request module. basically not master we

request module. basically not master we will just see a glimpse of it because

will just see a glimpse of it because request module is basically used to make

request module is basically used to make some API calls from Python if you do not

some API calls from Python if you do not know about API API stands for

know about API API stands for application programming interface that

application programming interface that means let's say you are a user okay and

means let's say you are a user okay and you are working as a data engineer

you are working as a data engineer obviously

obviously okay and your organization's data okay

okay and your organization's data okay is sitting on a third party

is sitting on a third party application

application okay now in In order to fetch this data,

okay now in In order to fetch this data, we will work with

we will work with API. We will work with API. So whatever

API. We will work with API. So whatever data we want, we will simply send the

data we want, we will simply send the request to this API. This API will go,

request to this API. This API will go, let's say these are your databases.

let's say these are your databases. Let's say these are your databases

Let's say these are your databases within the application. Okay. So this

within the application. Okay. So this API will go to the application. Okay. It

API will go to the application. Okay. It will send the request with all the

will send the request with all the details, credentials, uh sensitive

details, credentials, uh sensitive information, ID, password, everything.

information, ID, password, everything. Then it will simply bring back the data

Then it will simply bring back the data and you will receive the data back in

and you will receive the data back in the form of a response. That is the

the form of a response. That is the highle architecture of request module

highle architecture of request module that we get. Basically, we simply use

that we get. Basically, we simply use this API. API is the middleman between

this API. API is the middleman between you and the application from where

you and the application from where you're trying to fetch the data. Make

you're trying to fetch the data. Make sense? So we simply say hey API just go

sense? So we simply say hey API just go there and bring the data for us. It goes

there and bring the data for us. It goes there. It simply shares all the

there. It simply shares all the information with the application that

information with the application that you are the guy. These are your

you are the guy. These are your credentials. Can I take the data?

credentials. Can I take the data? Application will say yeah you can. Then

Application will say yeah you can. Then it will simply bring the data and it

it will simply bring the data and it will deliver the data to you. So that

will deliver the data to you. So that you cannot directly connect to the

you cannot directly connect to the application. You do it via API. You do

application. You do it via API. You do it via API. So request module is used

it via API. So request module is used for that particular purpose. Let's try

for that particular purpose. Let's try to make some API calls to the u publicly

to make some API calls to the u publicly available API endpoints. And let me just

available API endpoints. And let me just show you how you can just work with

show you how you can just work with APIs. Just a highle understanding

APIs. Just a highle understanding because it is totally a different

because it is totally a different concept when you work with APIs. In web

concept when you work with APIs. In web development, in app development, web

development, in app development, web development, you work more with APIs.

development, you work more with APIs. But being a data engineer, you should

But being a data engineer, you should know the some basic stuff of it. Okay,

know the some basic stuff of it. Okay, let me just show you because every API

let me just show you because every API is unique. It totally depends upon the

is unique. It totally depends upon the application developer or you can say the

application developer or you can say the team who has designed the API. So every

team who has designed the API. So every time you need to follow different

time you need to follow different different rules. So that is why it is

different rules. So that is why it is not a kind of generic rules for you as a

not a kind of generic rules for you as a data engineer. Every time you need to go

data engineer. Every time you need to go through the documentation that

through the documentation that application developers provide. Okay.

application developers provide. Okay. But let me show you how you can just

But let me show you how you can just perform some um you can say API calls,

perform some um you can say API calls, get API calls to simply fetch the data.

get API calls to simply fetch the data. Let me show you. So we going to use this

Let me show you. So we going to use this publicly available API and you can even

publicly available API and you can even just copy paste it. Let me just show

just copy paste it. Let me just show you. So it is saying like this. Okay.

you. So it is saying like this. Okay. And you can simply type it. It's not a

And you can simply type it. It's not a big URL. Okay. So let me just try to get

big URL. Okay. So let me just try to get this data. So basically this is a

this data. So basically this is a response when I hit this endpoint. So I

response when I hit this endpoint. So I need to get this data which is like user

need to get this data which is like user ID, ID, title and body. Okay, make

ID, ID, title and body. Okay, make sense? So obviously we can just use API

sense? So obviously we can just use API module which is request method. I will

module which is request method. I will simply import it. The thing is uh

simply import it. The thing is uh request module is not supportable by all

request module is not supportable by all the online compiler. So I'm not sure it

the online compiler. So I'm not sure it will work or not but we can simply test

will work or not but we can simply test it. We can simply run it. See no named

it. We can simply run it. See no named module request because sometime they

module request because sometime they have not updated the compilers. No

have not updated the compilers. No worries we can simply go to a different

worries we can simply go to a different compiler. I can simply say online python

compiler. I can simply say online python compiler and let's try this GDB one.

compiler and let's try this GDB one. Okay this GDB one. Okay makes sense. So

Okay this GDB one. Okay makes sense. So we can use this compiler for API calls.

we can use this compiler for API calls. No worries. I will simply say import

No worries. I will simply say import requests

requests requests. Okay, let me just run this

requests. Okay, let me just run this just to make sure it is running fine.

just to make sure it is running fine. Oh, it is running fine. Very good. We

Oh, it is running fine. Very good. We can use this. So now what we will do? We

can use this. So now what we will do? We will simply first of all fetch the URL.

will simply first of all fetch the URL. URL is this one. Okay, let me just copy

URL is this one. Okay, let me just copy and paste it. And here I will simply use

and paste it. And here I will simply use response equals

requests dot get requests dot get. So get method is the method that we use to

get method is the method that we use to fetch the data. Then I will simply pass

fetch the data. Then I will simply pass the URL. That's it. Let me just run

the URL. That's it. Let me just run this. Perfect. So we can easily make

this. Perfect. So we can easily make this API call to this particular URL.

this API call to this particular URL. Okay. Now we have some status codes

Okay. Now we have some status codes available in API. The success status

available in API. The success status code is popularly known as 200. If we

code is popularly known as 200. If we have any error we see 404. So similarly

have any error we see 404. So similarly we have so many status codes. Let's see

we have so many status codes. Let's see the status code for this one. I will

the status code for this one. I will simply say

simply say print response dot

status. Okay. We do not have any

Okay. We do not have any status. Response is not defined. Res

status. Response is not defined. Res response

response response response response

response response response response response object has no object

response response object has no object status. Maybe it will be having status

status. Maybe it will be having status code. Yep. Let's see. Okay, perfect. It

code. Yep. Let's see. Okay, perfect. It has status code 200. That means it is

has status code 200. That means it is successfully able to connect to that

successfully able to connect to that particular endpoint. Very good. That's

particular endpoint. Very good. That's what we want. Now I will just show you

what we want. Now I will just show you the data. What response did we get? We

the data. What response did we get? We resp we get response

resp we get response as print

as print response. So this is the response. This

response. So this is the response. This is the response. You will say there's

is the response. You will say there's nothing inside it. Yes, we will not get

nothing inside it. Yes, we will not get the data directly in response. Just to

the data directly in response. Just to convert or you can say just to fetch the

convert or you can say just to fetch the data from this response. We use

data from this response. We use something called as data variable equals

something called as data variable equals response dot JSON. If the result is in

response dot JSON. If the result is in the JSON format and we can see that it

the JSON format and we can see that it is in the JSON format, most of the API

is in the JSON format, most of the API calls will return the response in JSON

calls will return the response in JSON format. Now I can simply print this

format. Now I can simply print this data. Wow, this is the data that we got.

data. Wow, this is the data that we got. User ID, ID, title and everything. This

User ID, ID, title and everything. This is the way to make API calls to the API

is the way to make API calls to the API endpoint or basically to any URL using

endpoint or basically to any URL using requests.get get

requests.get get method. It is very handy. You can even

method. It is very handy. You can even work with status code. You can even work

work with status code. You can even work with data. You can even fetch directly

with data. You can even fetch directly the data. Once you have the data, you

the data. Once you have the data, you can even write the data as

can even write the data as well. You can even write the

well. You can even write the data. Make sense? Makes sense. Makes

data. Make sense? Makes sense. Makes sense. Okay. Very very very good. So

sense. Okay. Very very very good. So this was all about your request method.

this was all about your request method. Now I'm so sure that you are so so so

Now I'm so sure that you are so so so experienced and you have gained amazing

experienced and you have gained amazing skills in

skills in Python. Yes, there are so many other

Python. Yes, there are so many other things as well in Python that you can

things as well in Python that you can explore. Yes, there are so many modules

explore. Yes, there are so many modules in Python that that you can explore.

in Python that that you can explore. Yes, there are a lot of stuff because

Yes, there are a lot of stuff because Python is widely used. But I can say

Python is widely used. But I can say once you have completed this video, once

once you have completed this video, once you have completed all the areas that I

you have completed all the areas that I have mentioned in this video, you are

have mentioned in this video, you are wellversed with Python now you can

wellversed with Python now you can understand any new concept plus you can

understand any new concept plus you can even go deeper inside any existing

even go deeper inside any existing concept. Make sense? You can master any

concept. Make sense? You can master any module now because you have built a

module now because you have built a strong

strong base. Make sense? You are not a Python

base. Make sense? You are not a Python developer. You are not a web developer.

developer. You are not a web developer. You are a data engineer. You need to use

You are a data engineer. You need to use Python. Make sense? You need to

Python. Make sense? You need to selectively use modules. You need to

selectively use modules. You need to selectively combine your data with the

selectively combine your data with the modules. That's

modules. That's it. But yes, some things are common in

it. But yes, some things are common in all the things that are like classes,

all the things that are like classes, inheritance, um you can say functions,

inheritance, um you can say functions, all those things, multi-threading. Now

all those things, multi-threading. Now you are wellvered with all those things.

you are wellvered with all those things. Make

Make sense? So we

sense? So we have a very good module which is OS

have a very good module which is OS module. By the way, OS module will only

module. By the way, OS module will only be working with your local machine

be working with your local machine because obviously you need to just work

because obviously you need to just work with files. But we do not work much with

with files. But we do not work much with OS module as a data engineer. We work

OS module as a data engineer. We work with some alternatives such as DB utils

with some alternatives such as DB utils which is datab bricks utilities,

which is datab bricks utilities, notebook utils that are developed by

notebook utils that are developed by Azure notebook utils. But yes, you

Azure notebook utils. But yes, you should have some basic understanding of

should have some basic understanding of the OS module. Basically, let me just

the OS module. Basically, let me just talk a little bit about OS module. Okay,

talk a little bit about OS module. Okay, let's go here. I love this UI truly

let's go here. I love this UI truly speaking. Okay, let me just talk about

speaking. Okay, let me just talk about OS module a little bit and then I will

OS module a little bit and then I will just provide you some resources that you

just provide you some resources that you can explore because there's not any kind

can explore because there's not any kind of logic behind it. It's very simple. So

of logic behind it. It's very simple. So basically we can simply say import OS.

basically we can simply say import OS. Okay, let me simply run

Okay, let me simply run it. A module you have imported isn't

it. A module you have imported isn't available at the moment obviously

available at the moment obviously because this is just a online compiler

because this is just a online compiler you need like real machine, real

you need like real machine, real folders, real storage. Okay. But still I

folders, real storage. Okay. But still I will try my best to explain you some

will try my best to explain you some basic stuff that you can then you can

basic stuff that you can then you can just refer the documentation that I will

just refer the documentation that I will just show you. Basically OS module

just show you. Basically OS module stands for like operating system module

stands for like operating system module in which you can actually perform a lot

in which you can actually perform a lot of stuff. For example, you want to

of stuff. For example, you want to create a folder. You want to create a

create a folder. You want to create a folder. You can write things similar

folder. You can write things similar like OS dot make directories and then

like OS dot make directories and then you can simply provide the path any

you can simply provide the path any path. Okay. path of your local machine

path. Okay. path of your local machine like local C users your name and then

like local C users your name and then folder let's say you want to create um

folder let's say you want to create um or let's say remove the folders you can

or let's say remove the folders you can do that you can simply say rm diir s

do that you can simply say rm diir s there are like so many modules I will

there are like so many modules I will just show you there are so many

just show you there are so many functions then let's say you want to

functions then let's say you want to dynamically fetch the location or

dynamically fetch the location or basically absolute path of the python

basically absolute path of the python file that you are running you can simply

file that you are running you can simply perform something like this

perform something like this os.pathabs path and you can simply write

os.pathabs path and you can simply write something like

something like this.

this. Oops like this. So it will give you the

Oops like this. So it will give you the absolute path. Basically this module is

absolute path. Basically this module is used when you are making some file

used when you are making some file management but I know we data engineers

management but I know we data engineers work directly with the cloud storage

work directly with the cloud storage Azure AWS GCP that's why we use cloud

Azure AWS GCP that's why we use cloud utilities but yes you should also know

utilities but yes you should also know about operating system of Python as well

about operating system of Python as well because both are interlin if you

because both are interlin if you understand DB utils it will be a piece

understand DB utils it will be a piece of cake for you if you know OS DB utils

of cake for you if you know OS DB utils will be a piece of cake for you now it's

will be a piece of cake for you now it's the best time to just show you the OS

the best time to just show you the OS module. So it you can you can simply say

module. So it you can you can simply say Python OS

Python OS module. Okay. And let's try to see like

module. Okay. And let's try to see like Python OS module. So you can see there

Python OS module. So you can see there are so many functions and you can even

are so many functions and you can even go through this documentation. Okay. You

go through this documentation. Okay. You can see there are so many stuff OS

can see there are so many stuff OS objects OS things. You can even just

objects OS things. You can even just refer official documentation as well.

refer official documentation as well. So it is nothing but just a file

So it is nothing but just a file management. That's it. That's it. See it

management. That's it. That's it. See it has like so many classes fs.path so many

has like so many classes fs.path so many stuff. Get environment all these things.

stuff. Get environment all these things. If you have like environment variables.

If you have like environment variables. So these things are like much more used

So these things are like much more used at the time of

at the time of deployment. Okay. Make

deployment. Okay. Make sense? Makes sense. But still I will

sense? Makes sense. But still I will recommend you to just go through these

recommend you to just go through these documentation examples. See this is

documentation examples. See this is simply saying os.get cwd. This is

simply saying os.get cwd. This is basically the current working directory.

basically the current working directory. You will simply get like this. So this

You will simply get like this. So this is a very good example. Let me just give

is a very good example. Let me just give you a quick overview. Let's say you just

you a quick overview. Let's say you just want to get the current working

want to get the current working directory of your file. You will simply

directory of your file. You will simply run like this and you will get the

run like this and you will get the output like this. Wow. Let's say you

output like this. Wow. Let's say you want to

want to uh create the folder. So you can simply

uh create the folder. So you can simply use os.make directories. I just showed

use os.make directories. I just showed you. Okay. So you can simply create

you. Okay. So you can simply create directory like this. And this is the

directory like this. And this is the code for you. Nothing. You just need to

code for you. Nothing. You just need to define the parameters, paths. That's it.

define the parameters, paths. That's it. That's it. Then let's say you want to

That's it. Then let's say you want to list all the files and directories

list all the files and directories within the folder you are working with.

within the folder you are working with. You can simply say something called as

You can simply say something called as os.list directory. What it will do? It

os.list directory. What it will do? It will simply give all the folders all the

will simply give all the folders all the things within the folder. It is just a

things within the folder. It is just a file management thing that you can do as

file management thing that you can do as a data engineer. Make sense? So you can

a data engineer. Make sense? So you can simply go through the documentation.

simply go through the documentation. These are important. Yes, not very

These are important. Yes, not very important because you can get started

important because you can get started with these modules directly on the cloud

with these modules directly on the cloud as well. Okay. So, it's up to you how

as well. Okay. So, it's up to you how you want to get started. But I would

you want to get started. But I would recommend you to get started with this.

recommend you to get started with this. That is all about your Python for data

That is all about your Python for data engineering master class. I hope I

engineering master class. I hope I covered all those things which are very

covered all those things which are very very important because I wanted to make

very important because I wanted to make sure that I will cover all the

sure that I will cover all the non-negotiables.

non-negotiables. I know there are much more important

I know there are much more important stuff as well but these are your

stuff as well but these are your non-negotiables. That was the agenda of

non-negotiables. That was the agenda of this video as well so that you will

this video as well so that you will cover all the important stuff for data

cover all the important stuff for data engineers. Make sure that you are

engineers. Make sure that you are covering all the things with deep

covering all the things with deep knowledge. Okay, I hope you like this

knowledge. Okay, I hope you like this video. I hope you loved this video. On

video. I hope you loved this video. On my channel you have everything that you

my channel you have everything that you need to become a data engineer. So just

need to become a data engineer. So just go on my channel. Okay, just watch any

go on my channel. Okay, just watch any video because every video is covered

video because every video is covered from scratch. Just master any technology

from scratch. Just master any technology and you will become an efficient data

and you will become an efficient data engineer. Trust me. Okay. So just click

engineer. Trust me. Okay. So just click on the video that is appearing on the

on the video that is appearing on the screen and I will see you

Click on any text or timestamp to jump to that moment in the video

Most transcripts ready in under 5 seconds

One-Click Copy125+ LanguagesSearch ContentJump to Timestamps

Paste YouTube URL

Enter any YouTube video link to get the full transcript

Most transcripts ready in under 5 seconds

Get Our Chrome Extension

Get transcripts instantly without leaving YouTube. Install our Chrome extension for one-click access to any video's transcript directly on the watch page.

Add to Chrome — Free

Works with YouTube, Coursera, Udemy and more educational platforms

Get Instant Transcripts: Just Edit the Domain in Your Address Bar!

YouTube

←

→

↻

https://www.youtube.com/watch?v=UF8uR6Z6KLc

YoutubeToText

←

→

↻

https://youtubetotext.net/watch?v=UF8uR6Z6KLc

YouTube TranscriptPreparing your results…

YouTube Transcript:Python Full Course For Data Engineers [6+ HOURS]