in this full course you will learn the

basics of python programming

i'm beau carnes with freecodecamp.org

i've previously created one of the most

popular javascript courses on youtube

and i've created many python tutorials

now i've created this complete python

course for beginners you don't need any

previous programming experience to

follow along and all you need to code in

python is a web browser in this course i

will teach you all the core aspects of

the python programming language and i

will simplify the more complex topics

python is considered one of the most

popular programming languages in the

world and it's only growing in

popularity python excels in a wide

variety of scenarios such as shell

scripting task automation and web

development and it's also the language

of choice for data analysis and machine

learning but it can also adapt to create

games and work with embedded devices

we're going to jump right into it so you

can start coding your first python

program as soon as possible to get

started quickly we'll use a replit which

is an online ide that allows users to

code and run programs in a variety of

different languages all in a web browser

and later i'll show you how to get

python set up on your local operating

system after the first project i'll go

into more detail about each of the main

features of python the section is

comprehensive and detailed and in the

final section you will use what you've

been learning to code a blackjack game

with me guiding you every step of the

way throughout the course there will be

a little repetition of some of the key

python programming concepts to make sure

you have a deep understanding of the

language so let's get started we're

going to start by creating a simple rock

paper scissors game and we'll start by

going to replit.com replied provided a

grant that made this course possible and

replie is going to make it super easy to

get up and running really quickly so you

can either sign up or log in

and create an account i'm just going to

use my google account

okay now that you're logged into replit

you can either just click the create

button or this plus button over here to

create a new replit and i'll make sure

to create a python replit but you can

see you can also select all sorts of

different programming languages oh these

are just the ones that start with the

word python but so there's there's tons

of different programming languages you

can select but in this case we are just

going to use python and then i'll click

okay so let me just kind of show off

replica a little bit

this is where we're going to create our

python code i'm going to zoom in just a

little bit so we're going to write the

code right here and then we can see some

output over on the right side and then

you can create different files over on

the left side here

and then there's some other things like

you can connect to version control and

and

if you have environment variables we're

not even going to be discussing those in

this course there's a debugger you can

connect to a database and just some

other things but we're mainly going to

just be using this main.pi program to

write our program and we're going to see

the results in the console so i'm just

going to close this files window so

it's a little bigger here

i'm going to start off by showing you

how to create a variable with python so

this is a rock paper scissors game and

there's going to be a players a player

is going to have a choice and a computer

is going to have a choice so i'm going

to create a variable called player choice

choice

and i'm going to set that equal to rock

rock

so let's look at a few components about

this this is the variable name player choice

choice

and you can see

if you

we use an underscore that's just kind of

the convention for python to use an

underscore if you're going to have a

space in the variable name and we're

going to assign it that's what this

equal sign this is the assign operator

and we're going to assign it to a string

a string is just a word or a collection

of characters like rock and we're going

to put quotation marks around it now we

could have also used a single quotes

instead of double quotes as long as you

use the same quote on each side that's

what's important so we've now created a variable

variable called

called

playerchoice and assigned it to rock and

now we can reference this variable later

and whenever we reference the variable

called playerchoice it's going to

the code is going to automatically

replace that player choice with rock

so this is going to be a very

interactive project i hope you're

following along i hope you have already

got replit loaded up like this now

throughout this project i'm going to

tell you what the next thing to do is

and i want you to try doing it yourself

before you watch what i'm going to do so

periodically you'll want to pause the video

video

based on and what i say you and try to

implement what i say

before you come back to the video and

watch me implement it and see if you've

implemented the the same way

so i'm just going to zoom in one more

time and

this is the first thing i want you to do

see if you can make another variable on

the next line so you're going to press

return or enter to go to the next line

and this variable should be called

computer choice and you should set it to equal

equal paper

paper

okay so you can pause the video and see

if you can make a variable called

computer choice and set it to equal paper

so here it's pretty simple here it's

going to start simple but it's going to

get harder as we go so computer choice equals

equals

paper okay so like i said it's starting

simple but it's going to get more

complex as we go along

if you've done that you've now written

your first line of python code in this course

course

okay now i'm going to talk about functions

functions

a function is a set of code which only

runs when it is called

so i'm going to show you how to put this

code into a function

now one thing about python is that

indentation is very important

so after we create a we define the name

of a function any line of code that's

indented the same amount is considered

within that function

so i'm going to create a new line of

code at the top and i'm going to call it get

get choices

okay so we define the function with def

and get choices and i'm going to select

all these these two lines of code at the

same time and just press the tab key and

that's going to indent all these the

same amount

and you can see sometimes they'll be

squiggly lines and if you hover over

some of the squiggly lines it will tell

you something in this case it just says

the local variable called player choice

is assigned to but never used that's not

necessarily bad it's just it's just

telling us that usually if you create a

variable you're going to want to use it

later well we are going to use it later

we just haven't gotten to it yet so

sometimes the squiggly lines will

indicate there's some sort of error in

the code

usually i think it's the color red will

indicate an error but if it's a

different color it just may mean that

there's something maybe not quite right but

but

it's not really that big of a deal so if

you have a variable that's assigned to

but never used that's not going to stop

your program

but it's just saying that it's not this

variable isn't really being used for

anything yet but we will change that

this function i'm going to show you how

to call a function later but we're

creating a function called getchoices

that assigns these two variables and

it's also i'm going to put another line

at the very end here and it's a return statement

statement

and i'm going to return player choice

choice

this will indicate what's returned when

this function is called so later we'll

call this function get choices and it

will return

something it will return the player

choice which is right here we'll turn in

this case rock that we can use somewhere

else in our code

and i did just happen to put an extra

line here

that's just that's optional i put a

blank line here just to kind of

make things easy to kind of organize the

code a little bit so

different sometimes i'll just put an

extra line between different sections of

code and it just makes it easier to

identify the different sections when

you're looking at the code

for the computer those extra lines don't

mean anything the indentation though

definitely does mean something

so as long as every line of code is

indented the same amount as the previous

line of code then it's all within the

same function

okay so this is what i want you to do

see if you can change the return

statement so instead of returning player

choice it's returning the computer choice

so that's pretty simple

it's now returning the computer choice here

here

now i'm going to create another function

down here this is just going to be an

example function just so i can

demonstrate something to you and then

we'll delete it it's not going to be

part of our rock paper scissors game but

i'm going to create a new function

called greeting

and then i am going to add what it's

going to do oh yeah put the semicolon

you also know a colon so a function

always has to have a colon at the end of

how we define it so i'm going to return

a string and it's just going to say hi

and one thing you'll notice is that

there's no you don't have to put any

anything at the end of each line some

programming languages such as javascript

you're going to put a semicolon at the

line at the end of the line

but in python it doesn't matter you

don't put anything at the end of each

line so now i'm going to call the

function to call the function i just

type the name and i put the parentheses

at the end so it's going to say so

greeting is now going to call it's going

to call this function and that's going

to return the string hi

now it's not going to do anything with

the string because our program doesn't

do anything with the string that's been

returned it's not going to go into the

console or anything but let's add

additional code so we will

make this string hi go on to the console

first let me create a variable that

takes what this greeting function

returns so i'm going to type in response

equals greeting so now we set the the

what greeting is being returned to this

variable called response and now i can

use the print function

and i can print the response and this

will print it to the console so now i

can we have this green button here this

runs the program i'll click this green

button here and now we can see it's high so

so

this response is getting this high from

here and then we're printing it right

there okay i'm actually going to delete

and what i want you to try to do now is

to call the get choices function and

store the response in a variable called

choices and then print the value of

choices to the console

so you can pause and try that really

quick and then i'm going to show you how

okay so remember the variable is called choices

choices

and we're going to set that equal to

the get choices variable now ins or the

get choices function now instead of

typing out get choices you can see that

this code editor is actually giving us

suggestions on what we want to put in

here so i just typed in get and you can

see it's now saying get choices right

here so i can instead of typing out the

whole thing i can either click there or

i can just press the tab key and it's

going to fill in the rest of that

function name so that's just something

little that makes it easier to write a

program and you don't have to type out

every single thing so if you've already

created a function or a variable then

the the code editor then reply will will

suggest what you may want to fill in

when you're typing and most other code

editors do something similar it's called

code completion so

i'm going to but i still have to add

parentheses at the end and now i'm going

to print

the choices [Music]

[Music]

okay so i'm gonna just click this play

button to make sure it does what we're

trying to do yep it clicked paper great

great

now let's talk about dictionaries

dictionaries in python are used to store

data values in key value pairs so let me

okay so a dictionary is going to have

these curly braces at the beginning and

end and then here's a key value pair

there's one it's separated by a comma

and then here's another key value pair

so we're setting name

we're setting that to equal bow and

we're saying the color

to equal blue so here's the key here's

the value here's the key

here's the value

and the key or the value in a dictionary

can be a variable

like the color we could set that we

already created this variable here i'm

just going to copy the word choices and

we can put choices and you can see now

it's not surrounded by the quotation

marks so if you surrounded by quotation

marks it's a string but if we don't

surround it by quotation marks it's

getting the the variable here choices so

this would be set to

paper because that's what choice is

going to is going to equal so we're

about to delete this line because that

was just an example

but now before the return statement in

this function we're going to add a new

line we're going to create a variable

named choices and make it equal to a

dictionary the first key should be

player with a value of the player choice

actually this variable here

the second key should be computer with a

value of computer choice

and then we're going to update the

return statement

to return the the choices dictionary

now i'm not going to keep telling you to

pause and try it yourself so just the

rest of this time whenever i say what

we're going to do you'll know that after

i get done explaining it you can pause

it and try it yourself but that's what

so i'm going to create choices

and it's going to be a dictionary and

then it's going to have

a player

that's the key and the value is going to

be player

choice and i was just able to press tab

to fill that in and then we're going to

have computer

and it's going to be

computer choice

and you can see sometimes if it goes to

the next line there just won't be a line

number right here

but i can

move this over for now

and then i am going to oh i forgot to

put the equal sign that's what that red

squiggly line means so because the red

means there is a problem in the program

so it's not going to run correctly now

the orange just means that we haven't

used choices yet which we will right now

because we're going to return choices

choices choices

okay so now we don't have any squiggly

lines because we're using every variable

that we created and we're returning

choices here

so you may have noticed that player choice

choice

it does not actually get set to the

player's actual choice

so let's fix that

the input function gets input from a

user and will use it to get the player's choice

choice

so instead of having players choice

equal rock we're going to make players

rock paper

paper scissors

okay so this is how you get input from a

user we use the input function and this

is going to be something that's going to

be printed

we'll print to the console here

and whatever the result of this input

will be that the the player that the

user entered will get stored to this

variable which we then can use later in

our program

so let's just try that out i'll click run

run and

enter

let me just stop and run it again

okay enter a choice rock paper scissors

i'll just put rock

and now you can see the player's choice

we're still printing that and it's going

to print as rock

great now let's just clean up this code

a little bit we still have this here we

don't need that dictionary that's not

going to be part of our final code

and now we'll make it so the computer

can actually make a choice

so we're going to learn about importing

libraries creating lists and calling methods

methods

python libraries are a set of useful

functions so you don't have to write

code from scratch when you import a

library to your program you get access

to more features without writing

additional code

with basic python it's challenging to

get your program to do something

randomly but it's easy to choose

something randomly using the random library

library

so let me show you how we can import the

random library

import statements are used to import

libraries and they're usually put at the

top of a program so i'm going to press

enter a few times here to add some lines

at the top and i'm going to do import random

random

so now we are going we we've

imported the random library

so we're going to use that random

library soon but now let's learn about lists

lists

a list in python is used to store

multiple items in a single variable

lists are surrounded by brackets and

each item is separated by a comma so

here's an example i could create a

variable called food and set it to this

list it's going to have three items pizza

carrots

and eggs [Music]

[Music]

so this is a list of strings

and then you can also get a random item

from the list

using we're going to use now we've

imported random we can get a random item

by using that that random library so i'm

going to put dinner [Music]

[Music] equals

equals

random dot choice

and then i'm going to pass in the the

list here

so using the random library we can call

choice and then we can pass in

a list and it's going to choose a random

item from that list and

and set it to equal this dinner variable

so right now the computer choice always

equals paper but we want it to be a

random choice between rock scissors and paper

paper

so before the computer choice variable

is created we'll create a new variable

called options and assign it to a list

of the possible options rock paper

scissors then we'll set the computer

choice variable to be a random choice of

one of the items in the options list

okay i hope you already tried this now

but let me show you how that's going to work

work

we'll create options

and we'll set it equal to this list of

of rock

[Music]

paper scissors

and you can see the code editor will

often pop up these boxes with more

information about what we're doing to

give us some some help with what we're

trying to do here so we're going to set

this computer choice to be random

random

dot choice

food not food i was looking at the food

there we go

and let's just um try running this

program and seeing what happens so i'm

going to put rock

and then we see the computer chose

scissor it should be scissors that's why

we're testing it out i guess i

spelled that wrong okay so scissors with

an s so now let me try running it again

and you can see it shows scissors but if

we run it enough time it should now it's

choosing paper because it's choosing it

at random okay

okay

that's working

okay so now let's just delete all this

code after the get choices function we

don't need to test that get choices

function anymore and now

let's create a new function called check when

when

so you shouldn't know enough how to you

should know enough about how to create a function

function

so def check

[Music] when

when

so this is just an empty function with

nothing inside it yet

but before we add oh with the

colon so before we add any code inside

the function we're going to create some arguments

arguments

function can re functions can receive

data when they're called the data are

called arguments so when creating a

function you can specify arguments

inside the parentheses so we've been

using this empty parentheses but i can

uh put in tooth i can put in things

within these parentheses

when this function is called we're going

to give it two pieces of data we're

going to pass two pieces of data into

the function the first piece of data is

going to be player the second piece of

data is going to be computer

so the you can basically call these

anything you want uh these are just

we're creating new variables but when we

call these functions we'll pass in two

pieces of information that will then be

assigned to the variable names player

and computer that we can use inside the function

function

so for now let's

finish off with to a for a complete

function the function has to have some

code within the function

so let's just add a return statement

that's just going to return a list

containing the elements player and computer

so this check when function shouldn't

actually return this

this is just to kind of get get it

quickly created it should actually

return different things depending on the

player and computer arguments

an if statement will allow a program to

do different things depending on certain conditions

conditions

so an if statement will first check a

condition and if the condition is true

then all the lines of code under the if

statement that are indented the same

amount will execute so as a quick

example i can say

a equals three

b equals five

and then we can create an if statement here

here if

if

a is greater than b

b

yes

or we can do if a is

less than b or we can do if we want to

check if a and b are equal we can do

eq we we'll put two equal signs now this

is very important you never want to use

one equal sign because a single equal

sign is the assignment operator that's

how you assign what variables are equal

to so if you use a single equal sign or

like then if i put if a single equal

sign b without a double equal sign that

is going to

set a to equal b which is not what we

want the double equal sign

is going to check if a and b are the

same value basically it checks if two

values values are equal now you can also do

do

a not equal so if you use the

exclamation point that's not equal or

you can use

less than or equal to or you can do more

than or equal to

so i'm just going to delete all this for now

now

so now we're going to update this risk

turn statement uh before the return

statement we want to we're going to

check if player if player equals computer

computer

and if so if true will return the string

it's a tie

so let's do that if player

equals computer and this is something

that maybe you figured out yourself

before you before you're watching this

will return a string and the string is

going to be

okay so now it's only going to return so

a function does not have to return something

something

and for this function it's only going to

return something

if this is true if player equals computer

computer

if not it won't return anything and just

to make make you notice this see this

this

line is indented within the if statement

which is indented within this function

and just really quick thing to note

for a return statement parentheses are

optional so i could also

add parentheses like that but you don't

need them but for now i'm just gonna get

rid of them [Music]

[Music]

so currently when there's a tie the

program now returns it's a tie

but how does the player know that's true

now let's have the program print which

options that the player and the computer chose

chose

you can concatenate strings with the

plus operator

that just means you can combine strings

with other strings or strings with variables

variables

so let me show you how you can print

which options were chosen so i'm going

and then i'll put player so you chose

and then we have to add a space here

because it's going to print a space and

then it will choose it will print this

so if the player chose rock we'll say

you chose rock

and then we can concave so we

concatenated these together but we can

add another plus sign

and put another string here and it's

going to say

computer chose oh it's like being

now i'm just about to type it in but see

if you can figure out what to add at the

end here to put in what the computer chose

so computer chose

computer or the the value of this

so

a lot of times when with programming

there's a bunch of ways to do the same

thing so this is one way to combine

strings and variables together there's

another way that's a little simpler

called an f string

so an f string will allow you to make

strings with and with variables and

other python code

so to do that you just put a variable or

you just put f at the beginning of a

string so let me just give you an

example so we do age equals 25 we're

going to create a variable and then i'm

going to make an f string we'll make it

a print statement and i'm going to put a

string in here but instead of starting

with a quotation mark it's going to

start with an f

and then i'm going to put gem is and

then whenever you want to put a variable

or any kind of python code we're going

to put some curly braces and i'm just

going to put the variable within the

curly braces

so years old and i'll put the end of the string

string

or let me put a

period here

okay so gem is

age which is going to be 25 years old so

the f string is just a slightly simpler

way to combine the strings and the

variables so what i want you to do see

if you can figure out how to update this

line right here so it uses an f string

and it uses these curly braces instead

so yeah we're going to put f and i can delete

delete

a lot of these

things here [Music]

[Music]

and then i'm going to put some curly

there we go okay you cho there was a

comma here you chose player computer chose

chose computer

okay so now we've been able to put in

the variable within this string with the

so we're going to test this out uh so

in a code

the code in this function never gets run

so when we press the run button it's not

going to run any of the code within the

function unless the function is called

within the program so

so

we're not going to test out this

function all right now what i want you

to do is see if you can add a line to

call the check when function and then

so we're going to just do

check when rock

rock

or actually we have to pass in strings

here rock paper

paper so

so

this is going to it's going to call this

function with rock in terms instead of

player and paper instead of computer

so let me try stride running this program

program

you chose rock computer chose paper and

just don't worry about these little

icons sometimes they just block what's

in there but it's still behind that

little search icon so it's to see it's

doing you chose rock computer chose paper

paper

now let's get back to checking the winner

winner

so far this function is only going to

check if there's a tie

now we'll start adding code to check

different wing conditions

so let's learn about else and elif statements

statements

okay so down here i'm just going to give

you i'm just going to paste an example

so so here's the if statement if age is

greater than or equal to 18 it's going

to print this else so anytime this is

not true then it's going to print you

are a child

okay now here i've combined it with

something else the ellis statement ls

just stands for else if it combines else

and if so you have to put a condition so

if age is greater than or equal to 18

print you're an adult else if now we're

going to check if age is more than

greater than 12 you were a teenager

else if age is greater than 1 print you

are a child

or else if none of these other things

so and it's it's only going to do one of these

these

it's going to get to the for once it

gets to the first one that's true then

it's not going to check the rest it's

just going to kind of go to the next

line of code after all these statements

so it's just going to choose one and

once it gets the first one that's true

then it's be done with this whole

you can also check for two conditions at

once let me give you an example i'm just

going to delete all this code and i'm

going to create an alif statement here elif

elif

else if and we're going to check if

player is equal to rock

and i'm just going to type in the word and

and

and computer

is equal to scissors

scissors

so now i'm checking if

both these conditions have to be true so

this condition and

this condition have to be true before

the following

statement will happen which we're going

rock smashes [Music]

[Music]

scissors you

you when [Music]

[Music]

okay now

the next thing we're going to do let's

see if we can figure out how to do this

we're going to add another lf statement

and this time we'll check if players

equal the rock and computer is equal to

paper and if so we'll return paper

covers rock

so we're going to make this kind of

easier by just copying this code and

then i'm just going to paste in this and

then i'll just change this so players

equal the rock and computer is equal to

paper instead of scissors paper

paper

you lose

and we won't even have an exclamation

point anymore because it's not exciting

okay and you can kind of see there's a

few we could add a few more elif

statements to cover all the different situations

situations

but instead we're going to talk about refactoring

refactoring

refactoring is the process of

restructuring code while keeping the

original functionality when created pro

when creating a program it's common to

refactor code to make it simpler or more understandable

understandable

so we are actually going to refactor

this code that i've highlighted now

and we are going to instead use a nested

if statement

a nested if statement will make the code

more understandable at a quick glance like

like

so you can put an if statement inside

another if else or else statement

so you'll notice here the first elf

statement is if player equals rock and

the second l of statement is if player

equals rock so see if you can figure out

how to refactor this to

to

not have to use the and anymore we're

just going to use one if statement and

one else statement and then an if

statement under that

elif statement

if that doesn't make sense you can just

see what i do right now

so i'm going to just

move this down a little bit

i'm going to actually copy and paste

some of these items but we're going to

start with l if player equals rock we're

not going to have this

i'm going to put this on a new line and

say if computer equals scissors so first

we're going to check if player equals rock

rock

and then if so we're then going to check

it's going to be a nested if statement

if computer equals scissors and if

computer equals scissors then we're

going to use this this return statement here

here

so i have to make sure it's indented

correctly it's going to re so this we have

have

we have

player if player equals rock then if

computer equals scissors we'll return oh

this needs to be indented one more time

to be on inside that if statement

and now we don't even need this elf

statement this can just be an else

statement else

because if

the computer equals scissors there's

only one other option because we already

know if player equals rock and computer

equals rock will have already returned

it's a tie

and by the way once you return something

the rest of the code in a function does

not run so if we're returning it to tie

nothing else after that is going to run

so we know that computer can't equal the

rock at this point so it's either going

to be scissors or paper so i don't we

don't even have to check if computer

equals paper because at this point

computer has to equals paper and then

we'll just return this this line

let's see

there we go return paper covers rock

you lose

so now we just basically have to add two

more sections similar to this so this

one is if player equals rock

then we have to have another section if

player equals paper and then if player

equals scissors

and then we just have to have the the

stuff inside is going to be pretty

similar just corresponding to the

different relationships between rock

paper scissors

so i'm just going to copy that

and then i will paste it here and then

one thing is important to make sure this

elif statement

lines up with this else statement

and this is now going to be paper

paper

and then we are going to check if

computer equals rock

and a computer equals rock

then we will say that

you win

or we'll say scissors

cuts paper

paper

you lose and then the final one which at

this point i'm sure you can figure out

on your own we're going to add one more section

section

and this if

player equals scissors

and then first we're going to check if

computer equals paper

if so

we will do scissors

scissors cuts

cuts

paper we're just making sure we're just

making it so every time the first one is

you win the second one is you lose but

you could do it the other way around

rock smashes

smashes scissors

scissors

you lose

okay we're almost finished with this

whole program

so both

the get choices function and the check

win function they're both complete

now let code to call the functions and

play the game

so first let's remove this

this check when

now we'll create a variable called

choices and make it equal to the result

of calling the get choices function

and we just have to make sure it's not

indented it's on the the first

the first column i guess right here not

ended at all so we'll do choices

choices

equals get choices

choices [Music]

[Music]

and one thing about this is it's going

to return a dictionary so if we look at

the get choices

so it's returning choices and it's going

to be a dictionary like this now let me

just copy this i'm going to show you

something down here i'm going to just

paste it down here and we'll just make

an example of what it could look like it

could look like rock and paper i always

use rock and paper as examples because

scissors is a

little harder for me to spell

so so that's a little easier so so let's

one thing we haven't talked about is how to

to uh

uh

how to access a and specific element

within a dictionary so this is a

dictionary so let's say if i call this um

well i'll just call it choices even

because we're going to delete that and

so we're only going to have this choices

but if choices equals this and let's say

i just want to get the the choice of the player

player

let me show you how i would do that

i'll just do

p choice for player choice and i'm going

to put equal choices and to get just the

the value of the player i'm going to put

brackets so the brackets look like that

and then i have to

put the the key that i want the value of

so the key would be player

so if i

put the name of the dictionary which is this

this

and then i put some brackets we're going

to use brackets to identify what is the

key that we want the value of so here's

the key of the with the value of rock

and here's a key with a value of paper

so this is how we can get the player

choice and i'm sure you can under see

how you get the computer choices if

instead if

we take this computer word and put it

right here

uh computer

okay i'm just going to get rid of all

this here

and we're going to we have the get

choices here

and now listen carefully to what we're

going to do next

we are going to create a variable called

result and make it equal to the result

of calling the check win function and

when we call the check win function

we're going to pass in the value of the

player key

and the computer key

of the choices dictionary

so let's do that so then you'll see what

i mean a result

is going to be

we're going to call [Music]

[Music] check

check when

when

and then we are going to pass in

we're going to pass in we have choices player

player

computer

so because remember we had that we i

showed the example that dictionary so

we're getting the player key the value

of the player key and the value of the

computer key

so now we know who wins

we've now this result variable is going

to be one of these strings have been

returned either it's a tie rock space of

scissors paper covered rocks and so on

so now we just have to print the result

we're going to print

print

the result

okay we can try out this game

i'm going to click the run button

okay this is why it's sometimes better

to test a little earlier i just forgot the

the

semicolon on some of these so um semicolon

semicolon

and see there's a red arrow i should

have seen that semicolon

and semicolon

okay now let's try it i'm going to play

the program into a choice

i'm going to do

rock and i just noticed something else i

want to change so enter a choice here i

started there's a parenthesis here

there's no parentheses at the end so

again i'm just going to change that

really quick so enter a choice and we're

going to put it in parentheses here and

test again so rock okay you chose rock

computer chose rock

it's a tie okay i'm gonna play it again paper

paper

you chose paper computer chose scissors

scissors cuts paper you lose

okay we just created a python game

so hopefully this gives you a better

understanding of what it's like to

program in python and you you now know

about some of the basic concepts of

python now there's a lot more to learn

in python and we're going to be covering

a lot more in this course i just wanted

to start with a game and a full program

so just right off the bat you could go

to program

so in the next section i'm going to

start going over in detail all the most

common features of python

and we're going to cover some of the

features that we've already used in this

game plus a lot of additional features

additional common features that were not

used in this game

and then in the final section of the course

course

we're going to code a more complex game

a blackjack game

so let's get started with the next section

section

one of the quickest and easiest ways to

get started with python is by using

replit.com but you may also want to get

python running on your local computer so

if you want to do that you can start by

going on over to python.org

and these go to the downloads menu

and then you're going to just click

what you want to download for it for so

it's going to default to be for you the

operating system you're on but you can

also go to other platforms and make sure

you can and then just find the platform

that you want to download on and there's

going to be instructions on here that's

going to tell you how to go about

getting installed on your specific computer

computer

so there's a few different ways to run a

python programs and one of the ways is

with an interactive prompt so after you

get installed if you open up your

terminal and type in python or sometimes

it's going to be python 3 depending on

how you got it installed you're going to

see this interactive prompt and then you

can just this is called a python rebel

it's it's different from a rebel

creating with created with replit but

you can start coding in python right on

here so i could say

name equals bow

and then you have to make sure you

put the the quotation marks at the end

and now i've gotten a variable stored as

bow and then i can just type in the

variable name name and it's going to

show you show me the value of the

variable and you can type in most

different python commands right into

this inactive prompt here

and then i can just quit it when i'm

ready to quit

it's also common to run python using

visual studio code so if you just search

for visual studio code you can get to

the the download page and then you can

just download it for your system and

there's also you can download for

different systems and then once you open

up visual studio code to get python

working you're going to want to install

the python extension so i'm going to

click over here to extensions and you

can search for python or it may just be

listed here under popular extensions and

i'm just going to click install

and this is going to make it easier to

work with python on visual studio code

so now i can just kind of close some of

this stuff here

and i'm going to

create a new file

and i can just call the and i can just

type in name equals

equals bow

bow print

print name

name

and then if i save this as

as

test.pi it's going to now it's going to

add the colors that correspond to python

python

and then i'm just going to click this

play button here

and it's going to play it's going to

open up a terminal window here

and it's going to run the program and

it's going to print bow that's what my

program did if i zoom out a little bit

you'll be able to see the difference so

well we just print the name and it and

it runs the program just like that and

then you can see on the terminal how the

the command that was used to run that so

we could use the same command on any

terminal and instead of typing this

whole thing for the location of python 3

i can just do python

3 and then you this is where that file

is located so just copy that

and i can paste it in here and it's

going to run that program

in this section we'll learn about the

core features of python i'll go into

more detail about some of the things we

learned in the first project and they'll

be covering a lot more concepts this

section was heavily inspired by the

python handbook by flavio copes and you

can check that out on freecodecamp news

and like the first part of the course

i'll be running python in replit so once

you get logged into replit just like i

already showed you before you can hit

the plus button here or the create

button to create a new replit and then

you can search for the programming

language or you can just click it down

here python we'll just create a python repel

repel

and then we can instantly start creating

writing python code in replit

so like i showed before we got our

different files here we're just going to

start by using one file here and this

we're going to encode and this is where

it's going to

appear if we we run the code so i'm

going to

close off the list of files here

and let's just start at the beginning

again so you've gotten used to coding in

python through creating a rock paper

scissors game

but now we're going to

kind of do a deep dive into all the

basic commands of python so there's

going to be some review but we're going

to be going into more detail about each

of the elements and the first thing

we're going to talk about is variables

so we can create a new python variable

by assigning a value to a label using

the equal sign or the assignment

operator so let me give you an example

just like i was showing you before just

name equals bo

so let me just zoom in a little bit more

here and so now our variable name is

name and we've assigned it the value of bo

bo

and then we can also uh create we can

create a variable with a number so i

could do age equals

equals

39. so a variable name can be composed

of characters numbers and an underscore

character but and it cannot start with

the number

so it could be anything like name one

it could be all capital letters

it could

be it could have an underscore it can

start with an underscore like i said

like that and

and

you can see that these are all it's

putting these

red squiggly lines because it's showing

that that's not

actual python code if you're going to

create a variable you should be

assigning it to a value or you should be

using a variable that already exists but

i'm just showing you some different

examples of different variables now so

here's an example of an invalid variable

name if you just start with a number

like that that can't be a variable

because you can't start with a number

and i couldn't put something like test

exclamation point you can't use

exclamation points you can't use percent signs

signs

and other than that anything is valid

unless it's a python keyword so there

are some keywords a keyword is something

that's used to to write python like for if

if while

while

import these are all words that have

very specific meanings within python so

you cannot use them for a variable name

now there's no need to memorize them as

the python editor here will alert you if

you use one of those as a variable

so that was just like

if i say if equals hi

hi

and then you can see it's going to show

you right here with these squiggly lines

that we've done something wrong

invalid syntax because and then also you

can see that

it turns blue this word turns blue

because it's a keyword you can't use it

as a variable name

so like i said it's going to alert you

if you if you use a keyword as a

variable and you'll start to gradually

recognize them as part of the python

programming language syntax

now let's talk about talk about

expressions and statements in python so

an expression is any sort of code that

returns a value like for instance if you

do one plus one or if you just do a

string like

bow this is going to like this is going

to return to this is going to return the

string bow so a statement on the other

hand is an operation on a value

so for example these are this is a

statement here because we have an

operation we're assigning this to the

variable and then another statement

would be like this print name

name

so that's going to

be a statement because it's doing

something to the value now a program is

formed by a series of statements and

each statement is put on its own line

like we have these two lines here but

you can use a semicolon to have more

than one statement on a single line so i

i could put a semicolon here

and then if i run the program it's still

going to print the name and let's just

do that we already learned how to run a

program in replica click this button

right here but we can see it's going to

print bow and if i put these on two

different lines it's going to do the

same thing if i run the program it's

going to still do the same thing here

now let's talk about comments this is

something we haven't talked about in

this course yet so in the python program

everything after a hash mark is ignored

so if i put a hash mark i can say this

is a commented line and when we run the

program this line is going to be

completely ignored and then we can also

put in inline comment if i just put the

hash mark here this is an inline comment

and the cool thing about most code

editors including replit is it's going

to put comments going to make them gray

so you know that this isn't really part

of the program this is just some sort of

special note that the programmer wants

to put as part of the program

so i want to emphasize again how

important indentation is so it's very

meaningful in python so you can't

randomly indent things like you can't

just press tab here to indent here and

how this is kind of lined up here this

line up here you can see this red

squiggly line says unexpected expected indent

indent

so some other languages do not have

meaningful white space an indentation

doesn't matter but in python indentation matters

matters

so in this case if you try to run this

program we can run this and you'll see

an error right here showing up in red

here it says indentation error unexpected

unexpected indent

indent

because indentation has a special

meaning so i can just unindent that here

everything indented belongs to a block

like a control statement or a

conditional block or a function or a

class body and we'll be talking more

about those different blocks

now let's talk about data types python

has several built-in types

so for instance this is a string so

anything surrounded by quotation marks

is a string that's one data type and you

can check the type of a variable by

using the type function so i could say type

type

and then i'll put name and to make sure

to be able to see in the console i'm

going to print what the type is here

and if i press if i run the program

we'll see that the type is the class of

str which stands for string

and then we can test to see if something

is a string by comparing it to str so i

could do equals equals str

and then if i run that it's going to say

true because the type of name does equal

a string

and then we can also use is

instance so

i'm going to

uh so if we instead of doing type we do is

is

instance and then we

have to pass it two things so

the first thing we're going to pass it

so we have the is instance we're passing

it the name that's this variable and str

we're trying to see if name is an

instance of a string and if i run that

it should say true again

so we've been testing against the str

class the string class but it works the

same for other data types so so there

are some data types around numbers

so an integer number integer numbers are

represented using the int class or the

int class and floating point numbers or

fractions are a type of are the type

float so i can say age equals

equals 2

2

and then we can just check

and i can pass in the age and then i can

pass in an int

so if i run that

we're going to see that i've done

something wrong

oh i spelled that wrong there we go okay

now i'm going to try this and we'll see

true false it's not a false or it's not

a float because it doesn't have a

decimal point if i

did 2.9

then it should show that it is a float

because it has a decimal so python

automatically detects the type

from the value type so it automatically

knows this is a string it automatically

knows this is a float but you can also

create a variable of a specific type by

using the class constructor passing a

value literal or a variable name like

for instance we have this and we check

to see if this is a float and it's

saying false but i can make it a float

by typing in float

float

and just p putting the value

into the flow here so we're going to

make it a float so now it's true true

and you can do the same thing with

strings or integers or other data types

and you can also convert from one data

type to another by using the class

constructor so so that's basically what

we did we just converted this from an

integer to a float but i can also do

something else i can convert something from

from

a string

to an integer so for instance i'm going

to we'll just get rid of this one

completely here and we'll just use this

one so

a string is anything in quotation marks

so if i do

it's going to say

false it's not an n so i'm printing

whether it's an instance of an int but i

can convert this string

into an integer by just doing integer

and this let me run the program and it

says true

another thing about this is you don't

just have to pass in the actual data or

the actual string i can pass in a

variable so i can say number

equals and now i'm going to make it a an

x it says number but it's actually a

string but i can pass in the number here

and then it's going to set that to age

and it's going to be true so we create

the string we convert the string to an

integer and we tested that that age is

an integer

so when we do something like this this

is called casting

we are it's basically trying to extract

an integer from this string

of course the conversion might not

always work depending on the value

that's passed so for instance if we

write test here in the string

instead of the 20

we may get an air so let me just run

this and see now we have an error it

says invalid literal for

for int int with base 10 test so we

can't convert the word we can't convert

the string test to an integer so python

does its best to do the conversion but

it doesn't always work there are a few

other types so let me see are some other

common types of types so there's the

type of complex for complex numbers bool for booleans list for list tuple for

for booleans list for list tuple for tuples range for ranges

tuples range for ranges dict is our dictionaries and set

dict is our dictionaries and set is a type for sets

is a type for sets and we'll explore all these soon we'll

and we'll explore all these soon we'll go into more detail about about all

go into more detail about about all these different types of types well now

these different types of types well now let's talk about operators we've already

let's talk about operators we've already seen one operator that's this one that's

seen one operator that's this one that's the assignment operator but there's also

the assignment operator but there's also arithmetic operators comparison

arithmetic operators comparison operators logical operators bitwise

operators logical operators bitwise operators and plus some interesting ones

operators and plus some interesting ones like is and in so we're going to be

like is and in so we're going to be going over a lot of those right now

going over a lot of those right now so we talked about the assignment

so we talked about the assignment operator which is used to assign a value

operator which is used to assign a value to a variable or to assign a variable

to a variable or to assign a variable value to another variable now let's talk

value to another variable now let's talk about arithmetic operators

about arithmetic operators it's just what you use to do

it's just what you use to do math mathematics

math mathematics so here are the different

so here are the different arithmetic operators so we have plus one

arithmetic operators so we have plus one plus one equals two then minus

plus one equals two then minus multiplication division

multiplication division we have

we have remainder so four divided by three

remainder so four divided by three equals one but there's a remainder of

equals one but there's a remainder of one we have exponents four to the power

one we have exponents four to the power of 2 is 16 and floor division

of 2 is 16 and floor division so floor division does a

so floor division does a division problem and then just

division problem and then just basically rounds down

basically rounds down so floor division does the division and

so floor division does the division and rounds down to the nearest whole number

rounds down to the nearest whole number so actually this would be better seen if

so actually this would be better seen if we do four five divide by two five floor

we do four five divide by two five floor division divided by two is going to be

division divided by two is going to be two normally be 2.5 but floor division

two normally be 2.5 but floor division is rounding down to the nearest integer

is rounding down to the nearest integer the nearest whole number

the nearest whole number and then also note that that

and then also note that that the minus can also be a

the minus can also be a make something a negative number

make something a negative number so i could do 4 plus

so i could do 4 plus negative or i mean 1 plus negative 1 and

negative or i mean 1 plus negative 1 and then that's just going to equal 0. and

then that's just going to equal 0. and then the plus operator can also be used

then the plus operator can also be used to concatenate string values that's

to concatenate string values that's something we talked about earlier but i

something we talked about earlier but i could say

could say scamp

scamp and then put a plus

is a good dog and then like if i print this out

i put the the parentheses around it i can

can and then we'll see the whole string here

and then we'll see the whole string here sk scamp is a good dog

sk scamp is a good dog that was the name of my first dog when i

that was the name of my first dog when i was a kid so we can also combine these

was a kid so we can also combine these arithmetic operators with the assignment

arithmetic operators with the assignment operator let me show you what i mean so

operator let me show you what i mean so let me just get rid of this here and i'm

let me just get rid of this here and i'm going to do age

going to do age equals 8

equals 8 and age

and age plus equals

plus equals [Music]

[Music] 8

8 and i'll do print

and i'll do print age

age so we've so all these different

so we've so all these different operators can be assigned with it can be

operators can be assigned with it can be combined with the assignment operator

combined with the assignment operator and now it's going to add

and now it's going to add 8

8 to the age so if i

to the age so if i run this it's 16. so this actually just

run this it's 16. so this actually just means

means age

age equals age

equals age plus

eight so this age plus equals eight is the

so this age plus equals eight is the same as saying age equals age plus eight

same as saying age equals age plus eight so it's just going to add this number

so it's just going to add this number to the current age and set it equal to

to the current age and set it equal to the age and you can do that with any of

the age and you can do that with any of these like i could do

these like i could do times

times and that would be age equals age times 8

and that would be age equals age times 8 and

and 64. and so on with any of these

64. and so on with any of these arithmetic operators

arithmetic operators okay now let's talk about comparison

okay now let's talk about comparison operators

operators now we talked a little bit about them

now we talked a little bit about them before

before but let's see some examples again so

but let's see some examples again so this is to compare if two things are

this is to compare if two things are equal

equal and then we have not equal we're

and then we have not equal we're comparing them to see if they're not

comparing them to see if they're not equal or count this is if a is

equal or count this is if a is greater than b

greater than b or more than b and then this this is

or more than b and then this this is less than or equal to b

less than or equal to b now let me just tell you a trick of how

now let me just tell you a trick of how i keep the keep track of which one is

i keep the keep track of which one is greater than and which one is less than

greater than and which one is less than if you see this less than one if you

if you see this less than one if you kind of tilt your head a little bit it

kind of tilt your head a little bit it kind of looks like an l see like l and

kind of looks like an l see like l and this one doesn't look like as much of an

this one doesn't look like as much of an l so this

l so this less than operator kind of in some ways

less than operator kind of in some ways looks like a capital l that's kind of

looks like a capital l that's kind of just squished over and that's how i keep

just squished over and that's how i keep track of which one is less than which

track of which one is less than which one is greater than

one is greater than and so these are all going to give

and so these are all going to give either a false value or a true values

either a false value or a true values speaking of true and false

speaking of true and false true and false are examples of boolean

true and false are examples of boolean the boolean data type the boolean data

the boolean data type the boolean data type just means true false or true

type just means true false or true so a boolean is either going to be true

so a boolean is either going to be true or false there's only two options

or false there's only two options and there are a few boolean operators

so let me show you what the boolean the boolean operators are either not

boolean operators are either not and

and or or

or or so when working with two or false

so when working with two or false attributes

attributes those work like logical and or and not

those work like logical and or and not so when you're using uh not

so when you're using uh not it means it's not true you're checking

it means it's not true you're checking you're checking to see something is not

you're checking to see something is not true and means they both have to be true

true and means they both have to be true and or means either this one has to be

and or means either this one has to be true or this one has to be true in order

true or this one has to be true in order for the full thing to be evaluated as

for the full thing to be evaluated as true

true and let me show you something about or

and let me show you something about or now or using an expression returns the

now or using an expression returns the value of the first operator operand that

value of the first operator operand that is not a false value or a falsie value

is not a false value or a falsie value otherwise it returns the last operand so

otherwise it returns the last operand so it's going to return

it's going to return the first operand that is not a false

the first operand that is not a false value but since this is a false value

value but since this is a false value it's returning the second operand since

it's returning the second operand since this is a false value it returns the

this is a false value it returns the second one

second one since this is not a false value it will

since this is not a false value it will return the first one

return the first one and this is considered a false value if

and this is considered a false value if it's just an

it's just an empty bracket that's false so it's going

empty bracket that's false so it's going to return the second value which just

to return the second value which just happens to be false

happens to be false and since this is a false value it's

and since this is a false value it's going to return the second option which

going to return the second option which also happens to equal to false

also happens to equal to false so

so one way to think about it for the word

one way to think about it for the word or is so the pi this is how the python

or is so the pi this is how the python docs describe it if x is false

docs describe it if x is false then why

then why else x

else x so this would be like x this would be y

so this would be like x this would be y if else is false then why else x

if else is false then why else x and then for and down here let's look at

and then for and down here let's look at some examples for and and only evaluates

some examples for and and only evaluates the second argument if the first one is

the second argument if the first one is true so if the first argument is falsy

true so if the first argument is falsy such as false zero and empty string

such as false zero and empty string empty brackets it returns that argument

empty brackets it returns that argument otherwise it evaluates the second

otherwise it evaluates the second argument

argument so the way the way the python docs

so the way the way the python docs describe it is if x is false then x

describe it is if x is false then x else y

else y okay let's quickly discuss bitwise

okay let's quickly discuss bitwise operators they're very rarely used only

operators they're very rarely used only in very specific situations but it's

in very specific situations but it's worth knowing what these bitwise

worth knowing what these bitwise operators are just in case you're in the

operators are just in case you're in the very rare situation that you need to use

very rare situation that you need to use them

them and then two other types of operators

and then two other types of operators are is and in

are is and in now is is called the identity operator

now is is called the identity operator it's used to compare two objects and

it's used to compare two objects and returns true if both are the same

returns true if both are the same objects if both are the same object and

objects if both are the same object and i'll be talking more about that later in

i'll be talking more about that later in the section on objects and then in is

the section on objects and then in is called the membership operator this is

called the membership operator this is used to tell if a value is contained in

used to tell if a value is contained in a list or another sequence and we'll be

a list or another sequence and we'll be talking more about the in operator when

talking more about the in operator when we're discussing lists and other

we're discussing lists and other sequences later in this course

sequences later in this course and the final thing i want to talk to

and the final thing i want to talk to you about is the ternary operator now

you about is the ternary operator now the turn area operator in python allows

the turn area operator in python allows you to quickly define a conditional

you to quickly define a conditional so here will be like kind of the slow

so here will be like kind of the slow way to do it without a ternary operator

way to do it without a ternary operator so let's say you have a function that in

so let's say you have a function that in this function is comparing age with 18

this function is comparing age with 18 and it's going to return true or false

and it's going to return true or false depending on the risk result

depending on the risk result so instead of writing like this

so instead of writing like this we can implement it with a ternary

we can implement it with a ternary operator so let's do death

[Music] is

is adult i'll call it is adult 2 because

adult i'll call it is adult 2 because it's the second way of doing it and this

it's the second way of doing it and this time we're going to use the ternary

time we're going to use the ternary operator it's just going to be return

operator it's just going to be return true

true if age

if age is greater than 18

is greater than 18 else

so you can see first we define the result if the condition is true

result if the condition is true then we evaluate the condition

then we evaluate the condition and then we define the result if the

and then we define the result if the condition is false

condition is false it's basically an if else statement all

it's basically an if else statement all on a single line

on a single line okay let's talk more about strings in

okay let's talk more about strings in python so a string in python is a series

python so a string in python is a series of characters enclosed in quotes in

of characters enclosed in quotes in double quotes or it could be

double quotes or it could be single quotes

single quotes as long as the type of quote is the same

as long as the type of quote is the same on both sides and we already talked

on both sides and we already talked about how you can assign a string to a

about how you can assign a string to a variable

variable [Music]

[Music] and we already talked about how you can

and we already talked about how you can concatenate two strings using the plus

concatenate two strings using the plus operator like phrase

equals bo and then you can concatenate with the plus operator

with the plus operator is my

is my name

name [Music]

and then also instead of putting a string here

also instead of putting a string here you can put the variable so i could put

you can put the variable so i could put name is my name and we already have the

name is my name and we already have the variable here to equal bo so when you

variable here to equal bo so when you concatenate you can concatenate the

concatenate you can concatenate the strings or the variables

strings or the variables you can also append to a string using

you can also append to a string using the plus equal operator so let's say i

the plus equal operator so let's say i want to add to this name and i'm so i'm

want to add to this name and i'm so i'm going to say name

going to say name plus equals

is my name so we're adding is my name to the end of this so i can say

the end of this so i can say print

name and then we can see what it looks like

and then we can see what it looks like when you use the plus equal operator

when you use the plus equal operator so bo is my name

so bo is my name and then we already talked about how you

and then we already talked about how you can convert a number to a string using

can convert a number to a string using the

the str class constructor like if we had age

str class constructor like if we had age equals we could make this a string

equals we could make this a string but we passed this integer it converts

but we passed this integer it converts to a string and now it's going to be a

to a string and now it's going to be a string

string now here's something new a string can be

now here's something new a string can be a multi what can be multi-line when

a multi what can be multi-line when defined with a special syntax so if you

defined with a special syntax so if you enclose it if you enclose the string in

enclose it if you enclose the string in a set of three

a set of three quotes

quotes so let me show you an example get rid of

so let me show you an example get rid of all this

all this and i'm going to

and i'm going to print an entire

print an entire string here

string here so we're going to make this a multi-line

so we're going to make this a multi-line string i'm going to put three quotation

string i'm going to put three quotation marks

marks and then it's going to start with three

and then it's going to start with three quotation marks and end with three

quotation marks and end with three quotation marks and then i can make it

quotation marks and then i can make it multi-line so i can say bo is and then i

multi-line so i can say bo is and then i can

can put some extra lines

put some extra lines 39

39 years old now if i print that

years old now if i print that and you can see it's going to print

and you can see it's going to print the different lines here so we just made

the different lines here so we just made a multi-line string

a multi-line string and you can also instead of using the

and you can also instead of using the double quotes you can put a single quote

double quotes you can put a single quote as long as they're the same at the

as long as they're the same at the at the beginning and ending

at the beginning and ending now a string also has a set of built-in

now a string also has a set of built-in methods let me show you an example so if

methods let me show you an example so if i have this string

i have this string bow but i'm going to put at the end of

bow but i'm going to put at the end of the string i'm going to put dot

the string i'm going to put dot upper and i put parentheses at the end

upper and i put parentheses at the end so if i run this now it's going to print

so if i run this now it's going to print it in all capital letters

it in all capital letters and the same thing you can use with

and the same thing you can use with lower so if it if i had a string that

lower so if it if i had a string that had a few capital letters

had a few capital letters okay now it's all

okay now it's all lower now i can also type in a title

lower now i can also type in a title and this is going to

and this is going to make each lut so i can say

make each lut so i can say bow

bow person

person uh and i do this so it's going to cat

uh and i do this so it's going to cat it's going to a title that's going to

it's going to a title that's going to make the first letter of each string

make the first letter of each string a capital letter

a capital letter i can also check things like i can say

i can also check things like i can say is lower and it's going to check if it's

is lower and it's going to check if it's all lowercase letters false but if i

all lowercase letters false but if i make it so it is all lowercase letters

make it so it is all lowercase letters it's going to say true so here's just a

it's going to say true so here's just a list of a few common ones

list of a few common ones [Music]

[Music] you can do is alpha to check if it

you can do is alpha to check if it contains only characters

contains only characters is

is l num to

l num to check if a string contains characters or

check if a string contains characters or digits and is not empty is decimal

digits and is not empty is decimal lower to make it lower case is lower

lower to make it lower case is lower upper is upper title starts with to

upper is upper title starts with to check if it starts with a specific

check if it starts with a specific substring to check if it ends with you

substring to check if it ends with you can replace part of a string split a

can replace part of a string split a string you can strip the white space

string you can strip the white space from a string you can append new letters

from a string you can append new letters to a string you can find the position of

to a string you can find the position of a substring spring string and there's a

a substring spring string and there's a few more but these are some of the most

few more but these are some of the most common things you can do with a string

common things you can do with a string and then one thing to know about these

and then one thing to know about these is that they they all return a new

is that they they all return a new modified string they don't actually

modified string they don't actually alter the original string so let me show

alter the original string so let me show you what i mean by that so let's say we

you what i mean by that so let's say we have we'll do name equals bow again let

have we'll do name equals bow again let me zoom in a little bit

me zoom in a little bit and we're going to

and we're going to print

print name dot lower

now i'm going to print name

name so if i just run this

and we first figure out what went wrong here it looks like there's a few extra

here it looks like there's a few extra parentheses

parentheses [Music]

okay let's run this and you can see it's going to make it all lowercase but then

going to make it all lowercase but then when i print the name again

when i print the name again it's not still lowercase because this

it's not still lowercase because this just returns a brand new modified string

just returns a brand new modified string it doesn't actually change anything

it doesn't actually change anything in the original string

in the original string and then you can use some global

and then you can use some global functions with strings as well so one

functions with strings as well so one function we haven't discussed yet is the

function we haven't discussed yet is the l e n function which stands for length

l e n function which stands for length it can give the length of a string so

it can give the length of a string so i'm going to type an l-e-n

i'm going to type an l-e-n and then so there's just some global

and then so there's just some global functions that work with a lot of

functions that work with a lot of different types of data and the length

different types of data and the length of this is four you can see

of this is four you can see and then you can use the in operator now

and then you can use the in operator now i briefly mentioned the n operator

i briefly mentioned the n operator earlier so

earlier so let me show you one use case so we can

let me show you one use case so we can use the in operator to check if a string

use the in operator to check if a string contains a substring like for instance i

contains a substring like for instance i can say

can say a u

a u in

in name so let's check if name

name so let's check if name contains the letters a u

contains the letters a u well true it does but if if if it if it

well true it does but if if if it if it if it didn't if i just add an extra

if it didn't if i just add an extra string it's going to say

string it's going to say false

false okay another thing with strings um

okay another thing with strings um escaping is a way to add special

escaping is a way to add special characters into a string

characters into a string for example let's say we wanted to add a

for example let's say we wanted to add a double quote within the string how can i

double quote within the string how can i add a double quote into a string that's

add a double quote into a string that's wrapped in double quotes if i put a

wrapped in double quotes if i put a double quote like that that's not going

double quote like that that's not going to work because this is going to be the

to work because this is going to be the string and then it's not going to the

string and then it's not going to the code editor is not going to know what to

code editor is not going to know what to do with this last little bit here

do with this last little bit here so

so the way to go is to escape the double

the way to go is to escape the double quote inside the string with the

quote inside the string with the backslash character so right before this

backslash character so right before this quote i'm going to put the backslash

quote i'm going to put the backslash character

character and then you can see it now all is all

and then you can see it now all is all the same color as a string and if i

the same color as a string and if i print it it's going to it's not going to

print it it's going to it's not going to print the backslash character so putting

print the backslash character so putting a backslash is how you escape a

a backslash is how you escape a character and that just means

character and that just means this

this the the backslash character means that

the the backslash character means that the next character is not going to mean

the next character is not going to mean what it normally means

what it normally means it's going to actually just be the

it's going to actually just be the string of that character

string of that character and you can do the same thing with so

and you can do the same thing with so with in this particular example you may

with in this particular example you may not need to do it because you can always

not need to do it because you can always just put a single quote at the beginning

just put a single quote at the beginning and ending

and ending and as long as you have a different type

and as long as you have a different type of quote at the beginning and ending

of quote at the beginning and ending then

then you can put a double quote in the middle

you can put a double quote in the middle but let's say you want a string that

but let's say you want a string that contains both a single quote and double

contains both a single quote and double quote within the string

quote within the string then you will have to backslash like if

then you will have to backslash like if i just put a single quote there it's

i just put a single quote there it's going to mess it up but if i put it

going to mess it up but if i put it backslash

backslash now it's going to have the single the

now it's going to have the single the double quote and the single quote right

double quote and the single quote right within the string

within the string and

and you can also use the escape character

you can also use the escape character for

for special formatting characters like uh

special formatting characters like uh for instance what if i want there to be

for instance what if i want there to be a new line between the first two and the

a new line between the first two and the last two letters of the string if i do

last two letters of the string if i do slash n

slash n that is going to not actually just put a

that is going to not actually just put a slash in let's see what happens when i

slash in let's see what happens when i put that this is means new line you can

put that this is means new line you can see it says be new line a you

see it says be new line a you and then another way a reason why you

and then another way a reason why you may want to use an escape here like

may want to use an escape here like let's see what happens if i do this

let's see what happens if i do this this

this that's not looking how i want to look

that's not looking how i want to look because it's normally normally when

because it's normally normally when the code is running if it sees this

the code is running if it sees this backslash it thinks it's an escape

backslash it thinks it's an escape character so if you want to actually add

character so if you want to actually add a backslash to a string you have to

a backslash to a string you have to escape the backslash so now it's be

escape the backslash so now it's be backslash au

backslash au okay we're done talking about escape

okay we're done talking about escape characters now i'm going to tell you how

characters now i'm going to tell you how you can get a specific character in a

you can get a specific character in a string so given a string you can get its

string so given a string you can get its character using square brackets to get a

character using square brackets to get a specific item given its index starting

specific item given its index starting from zero

from zero so

so one thing to know about programming is

one thing to know about programming is that

that whenever you're counting from in most

whenever you're counting from in most programming languages you start counting

programming languages you start counting starting at zero so this is going to get

starting at zero so this is going to get the letter at index one so this is index

the letter at index one so this is index zero the b the e is at index one index

zero the b the e is at index one index two index three so if i run that we can

two index three so if i run that we can see we are getting the e that's at index

see we are getting the e that's at index one if i want to get the b i just put a

one if i want to get the b i just put a zero in the brackets and we get the b

zero in the brackets and we get the b and then we can use a negative number to

and then we can use a negative number to start counting at the end so if i put

start counting at the end so if i put negative one it's going to start here

negative one it's going to start here zero

zero one and that's going to be a oh you okay

one and that's going to be a oh you okay i guess when it's going backwards it's

i guess when it's going backwards it's not going to start zero because there is

not going to start zero because there is no negative zero that makes sense so

no negative zero that makes sense so negative one is going to be the last

negative one is going to be the last character in the string so negative one

character in the string so negative one negative two negative three and so on

negative two negative three and so on we can also use a range using what we

we can also use a range using what we call slicing so if i put 1 colon 2

call slicing so if i put 1 colon 2 this is going to be every character

this is going to be every character starting at index 1

starting at index 1 and ending before index 2. so it starts

and ending before index 2. so it starts at index 1 so it starts with that

at index 1 so it starts with that character and it ends before an x2 which

character and it ends before an x2 which is a so that's actually only going to

is a so that's actually only going to return an e

return an e but if i put 3 here

but if i put 3 here now we can return a u

now we can return a u and if i put bo is cool we can put one

and if i put bo is cool we can put one further down i'm going to put 7

further down i'm going to put 7 and we can see

and we can see it's going to return part of this string

it's going to return part of this string and then you can also start if you just

and then you can also start if you just put a blank before the colon then it's

put a blank before the colon then it's going to turn everything up to it's

going to turn everything up to it's going to start at the beginning and

going to start at the beginning and return everything up to character seven

return everything up to character seven and you can also do in the opposite

and you can also do in the opposite direction so if i put a blank after the

direction so if i put a blank after the colon it's going to go to the end of the

colon it's going to go to the end of the string so it's going to say is cool

string so it's going to say is cool so let's talk about

so let's talk about booleans well we already talked more

booleans well we already talked more about we already talked about booleans

about we already talked about booleans but we're going to talk a little bit

but we're going to talk a little bit more about boolean which is considered

more about boolean which is considered the bool type and this can have two

the bool type and this can have two values true or false so i can say done

values true or false so i can say done equals

equals true

true or you can do done

or you can do done equals false now

equals false now notice that it always has a capital t or

notice that it always has a capital t or a capital f so

a capital f so if you don't put a capital t or capital

if you don't put a capital t or capital f it won't be considered the the true

f it won't be considered the the true boolean value in python

boolean value in python and booleans can be especially useful

and booleans can be especially useful with the conditional co

with the conditional co with conditional control structures like

with conditional control structures like if statements

if statements well we already discussed if statements

well we already discussed if statements in the first part of the course and

in the first part of the course and we'll be discussing them more in detail

we'll be discussing them more in detail later but let me just show you an

later but let me just show you an example so if done and i'm going to

example so if done and i'm going to erase this done because we want to be

erase this done because we want to be true so if done

true so if done and then we'll say print

yes [Music]

[Music] else

else print

no okay so i can run that and it's going to

okay so i can run that and it's going to print yes because done

print yes because done equals true but if done equals false

equals true but if done equals false [Music]

[Music] then it's just going to say

then it's just going to say no

no so when evaluating a value for true or

so when evaluating a value for true or false if the value is not a bool or

false if the value is not a bool or boolean like if it's not true or false

boolean like if it's not true or false we have some rules depending on the type

we have some rules depending on the type we're checking so numbers are always

we're checking so numbers are always true

true except for the number zero

except for the number zero if i put 0 here it's going to evaluate

if i put 0 here it's going to evaluate to false but if i put any other number

to false but if i put any other number here it's going to be true even like

here it's going to be true even like negative 1 or anything like that it's

negative 1 or anything like that it's going to be true oh i guess

going to be true oh i guess that i didn't put negative 1 i put

that i didn't put negative 1 i put equals 1. so if it's negative 1 that's

equals 1. so if it's negative 1 that's going to be true

going to be true so strings are always false

so strings are always false oh

oh strings are false only when empty

strings are false only when empty so if i say

so if i say bow here this is going to be true

bow here this is going to be true because it's not an empty string but if

because it's not an empty string but if i make an empty string then it's going

i make an empty string then it's going to be

to be false

false lists tuples and sets and dictionaries

lists tuples and sets and dictionaries which we'll talk about more later are

which we'll talk about more later are false only when empty so it's going to

false only when empty so it's going to be if a list double star dictionary is

be if a list double star dictionary is is filled with something that is true

is filled with something that is true and then also you can

and then also you can check if a value is a boolean so if i

check if a value is a boolean so if i say done equals true

say done equals true i can do

i can do print

type we're going to check the type we're going to check if the type of done

going to check if the type of done equals

equals bool so let's check it does that equal

bool so let's check it does that equal boolean

boolean true it does now let's see let's

true it does now let's see let's change this to a different type and it's

change this to a different type and it's going to say false so it can still

going to say false so it can still evaluate whether this is true or false

evaluate whether this is true or false but the type is not a boolean the type

but the type is not a boolean the type is a string

is a string and let me show you another example code

so the global the any function it's a global function

the any function it's a global function it's very useful when working with

it's very useful when working with booleans

booleans it returns true if any of the values of

it returns true if any of the values of the iterable such as a list if any of

the iterable such as a list if any of them are true it's going to return true

them are true it's going to return true for all of them so

for all of them so for instance book one read that's true

for instance book one read that's true but book two read that's false but this

but book two read that's false but this is going to return true because it's

is going to return true because it's checking if any of them are true and

checking if any of them are true and then it's going to set this to true

then it's going to set this to true now the all function is is similar but

now the all function is is similar but returns true if

returns true if all of the values are true so

all of the values are true so we see we have this value as true

we see we have this value as true we have this value as false

we have this value as false whereas any would have returned true

whereas any would have returned true this is going to return false because it

this is going to return false because it only returns true if all of the values

only returns true if all of the values are true

are true okay now let's talk about more

okay now let's talk about more number data ties we already talked about

number data ties we already talked about int an integer whole number we've

int an integer whole number we've already talked about float which is any

already talked about float which is any number with a decimal point there's

number with a decimal point there's another type called complex

another type called complex complex numbers are an extension of the

complex numbers are an extension of the familiar real number system in which all

familiar real number system in which all numbers are expressed as a sum of a real

numbers are expressed as a sum of a real part

part and an imaginary part

and an imaginary part imaginary numbers are real multiples of

imaginary numbers are real multiples of the imaginary unit which is the square

the imaginary unit which is the square root of negative one often written

root of negative one often written i in mathematics or j in engineering

i in mathematics or j in engineering python is built in support for complex

python is built in support for complex numbers which are written with

numbers which are written with the the j notation so the imaginary part

the the j notation so the imaginary part is written with a s with a j suffix

is written with a s with a j suffix so you can combine it you can use a

so you can combine it you can use a literal value like complex

equals two plus

two plus three j so the the j means it's the

three j so the the j means it's the imaginary part of the number or you can

imaginary part of the number or you can use the complex constructor so i can put

use the complex constructor so i can put num

num equals

equals complex

complex and then i can pass in

and then i can pass in two comma three so

two comma three so the three part is the imaginary part the

the three part is the imaginary part the two is the the real part the integer

two is the the real part the integer part

part and then once you have a complex number

and then once you have a complex number you can get it's real or imaginary part

you can get it's real or imaginary part like this so i can say print

like this so i can say print [Music]

[Music] num

num dot real

dot real or num

or num dot match

dot match so this is going to be the 2 this is

so this is going to be the 2 this is going to be the 3. so if i just

going to be the 3. so if i just uh

uh let me

let me i think the problem was

i think the problem was num

num num one no so i'll do num one and num

num one no so i'll do num one and num two and we're gonna do this as num two

two and we're gonna do this as num two okay let's check this so

okay let's check this so this is the real part this is the

this is the real part this is the imaginary part you can see they're being

imaginary part you can see they're being returned as floats

returned as floats and you can use the type function to

and you can use the type function to check the type

check the type so now let's talk about some built-in

so now let's talk about some built-in functions that help with numbers so one

functions that help with numbers so one of them is abs abs will return the

of them is abs abs will return the absolute value of a number so if i say

absolute value of a number so if i say 5.5

5.5 that's just going to be

that's just going to be 5.5 but if i put negative 5.5 well

5.5 but if i put negative 5.5 well it will be 5.5 so

it will be 5.5 so [Music]

[Music] so if i print this see 5.5 basically it

so if i print this see 5.5 basically it just makes it so it's not negative

just makes it so it's not negative then you can also use

then you can also use round so if we do round

round so if we do round let's make this just 5.5 round is going

let's make this just 5.5 round is going to round to the nearest integer so if i

to round to the nearest integer so if i do this it's just gonna be six so point

do this it's just gonna be six so point five is going to round up but if we did

five is going to round up but if we did uh

uh four nine

four nine it's going to go down to five

it's going to go down to five you can also specify a second parameter

you can also specify a second parameter to set the decimal points precision so

to set the decimal points precision so i can

go to if i do one here and i round it it's going to

one here and i round it it's going to instead of rounding to the nearest

instead of rounding to the nearest integer it's now going to round to the

integer it's now going to round to the nearest tenths place value or one

nearest tenths place value or one decimal point

decimal point there are several other math utility

there are several other math utility functions and constants that are

functions and constants that are provided by the math standard library

provided by the math standard library like there's a math package a c math

like there's a math package a c math package decimal pages fractions package

package decimal pages fractions package that makes it easier to work with

that makes it easier to work with different types of numbers we'll explore

different types of numbers we'll explore some of those more later on

some of those more later on now let's talk about in nums and noms

now let's talk about in nums and noms are readable names that are bound to a

are readable names that are bound to a constant value so to use a noms we're

constant value so to use a noms we're going to have to import and numbs from

going to have to import and numbs from the inum standard library module

the inum standard library module like this from enum import enum and now

like this from enum import enum and now we'll be talking more about

we'll be talking more about importing

importing stuff from modules later but once you

stuff from modules later but once you import it then we can initialize a new

import it then we can initialize a new and nom in this way so do class

and nom in this way so do class state enum

and so we can have inactive [Music]

[Music] equals 0

equals 0 and active

and active [Music]

[Music] equals one

equals one so basically the the word state this can

so basically the the word state this can be anywhere any

be anywhere any word we like so we're setting

word we like so we're setting uh

uh basically a variable called

basically a variable called state.inactive

state.inactive which is going to equal 0 or

which is going to equal 0 or state.active to equal 1.

state.active to equal 1. so

so you can reference this how you would

you can reference this how you would reference it you can do print

reference it you can do print state

state dot

dot active

active and then if i just run the program we'll

and then if i just run the program we'll see

see now you can see it's just going to

now you can see it's just going to return state to active instead of one

return state to active instead of one so to actually get the value you use

so to actually get the value you use state to active dot value

state to active dot value and then we run that and then we'll see

and then we run that and then we'll see one here

one here if you we want to just return

if you we want to just return state.active that the sa that value can

state.active that the sa that value can be reached by the number assigned in the

be reached by the number assigned in the num so state we can do

num so state we can do one

one and if i print that it's now going to

and if i print that it's now going to say state.active

say state.active same for using the square brackets

same for using the square brackets notation so i could do states

notation so i could do states i'll do see square brackets and put

i'll do see square brackets and put active

active if i print that it's going to print

if i print that it's going to print state that active so this is basically

state that active so this is basically the only way to create constants in

the only way to create constants in python

python python is no way to enforce the variable

python is no way to enforce the variable should be a constant so some people use

should be a constant so some people use enums to create a constant

enums to create a constant and then nobody can reassign the value

and then nobody can reassign the value so

so when we do

when we do state

state or state active dot

or state active dot value

value so this is it's not going to be able to

so this is it's not going to be able to be reassigned so basically there's two

be reassigned so basically there's two ways to do we can do this bracket

ways to do we can do this bracket notation or we can go back to the other

notation or we can go back to the other way

way active

active now we can also list all the possible

now we can also list all the possible values for enum so

values for enum so our num is called state and we can now

our num is called state and we can now just print all the values oh i actually

just print all the values oh i actually did that wrong it's supposed to be a

did that wrong it's supposed to be a list

list so this is going to list the values of

so this is going to list the values of the state

the state and we can see we have inactive 0 and

and we can see we have inactive 0 and active is 1. and we can also count them

active is 1. and we can also count them using the length function so we're going

using the length function so we're going to print the result of a length state

to print the result of a length state and that's just going to give us 2.

and that's just going to give us 2. okay let's talk about more about user

okay let's talk about more about user input now we already discussed a little

input now we already discussed a little bit in our first program

bit in our first program but you can do get user input by using

but you can do get user input by using the input function so let's just get rid

the input function so let's just get rid of all this

of all this and we'll do

and we'll do age

age equals input

equals input and we can say

and we can say print

your age is and then we just can concatenate that

and then we just can concatenate that with the

with the variable age and then also if you want

variable age and then also if you want to

to so let's just do a quick test and right

so let's just do a quick test and right now it's looking for the age right now i

now it's looking for the age right now i can put five your age is five so there's

can put five your age is five so there's two ways to make it say what is your age

two ways to make it say what is your age we can do a print statement right before

we can do a print statement right before here

here and do what is

and do what is your age

your age and then

and then now we can put four your age is four

now we can put four your age is four now you can also ins instead of

now you can also ins instead of putting the print statement right before

putting the print statement right before here i'm going to copy this delete that

here i'm going to copy this delete that and we can put it right in this input

and we can put it right in this input function

function and then i'll say it'll still say what

and then i'll say it'll still say what is your age and i can

is your age and i can put an age here

so one thing to really realize about this is that it gets the input at

this is that it gets the input at runtime meaning the program will stop

runtime meaning the program will stop execution and will wait until the user

execution and will wait until the user types something and presses the enter

types something and presses the enter key

key you can also do more complex input

you can also do more complex input processing and accept input at program

processing and accept input at program invocation time and we'll see how to do

invocation time and we'll see how to do that later on

that later on if you want to get the input when the

if you want to get the input when the program is run that's going to work

program is run that's going to work better for command line applications

better for command line applications other kinds of applications will need a

other kinds of applications will need a different way of accepting input

different way of accepting input let's look more at control statements

let's look more at control statements this is another thing we've already

this is another thing we've already discussed earlier but we're going to

discussed earlier but we're going to review it and and look at it in a little

review it and and look at it in a little more detail so a control statement is

more detail so a control statement is like an if statement so if condition

like an if statement so if condition that's this variable here equals true

that's this variable here equals true then it's going to run everything in the

then it's going to run everything in the block a block is

block a block is the part that is indented one level

the part that is indented one level usually it's going to be either four or

usually it's going to be either four or two spaces in this case it's four spaces

two spaces in this case it's four spaces sometimes it's two spaces it doesn't

sometimes it's two spaces it doesn't matter it could even be one space as

matter it could even be one space as long as it's the same as long as every

long as it's the same as long as every line of code is indented the same amount

line of code is indented the same amount so if i just run that

so if i just run that the condition was true the block can be

the condition was true the block can be formed by a single line or multiple

formed by a single line or multiple lines and it ends whenever you move back

lines and it ends whenever you move back to the previous indentation level

to the previous indentation level so

so for instance if once we are not indented

for instance if once we are not indented i can say print

i can say print outside

outside if

if so then

so then that's always going to pres it's always

that's always going to pres it's always going to print this because it's not in

going to print this because it's not in that if statement

that if statement and then we have the if else statements

and then we have the if else statements where the else is if

where the else is if if this does not true then it's going to

if this does not true then it's going to do whatever is in here so if i just

do whatever is in here so if i just change this to false

change this to false then it's going to

then it's going to print whatever the condition was false

print whatever the condition was false and then we can have this series this is

and then we can have this series this is something that we showed in the per the

something that we showed in the per the program earlier but if and then elif

program earlier but if and then elif combines else and if so

combines else and if so if this is not true then i'll move on to

if this is not true then i'll move on to this line and else

this line and else if this is true then i'll do this else

if this is true then i'll do this else if this is true and it'll just keep

if this is true and it'll just keep going on and then it will always do the

going on and then it will always do the this is if none of the other ones were

this is if none of the other ones were true it's going to do this

true it's going to do this so since

so since it was testing this it's not even going

it was testing this it's not even going to evaluate anything later but if we

to evaluate anything later but if we move this to false

move this to false and we change this to bow

and we change this to bow then it's actually going to skip all the

then it's actually going to skip all the way down

way down all the way to this else here

all the way to this else here and if we do flavio

and if we do flavio you can print that and then it's going

you can print that and then it's going to say hello flavio from right here

to say hello flavio from right here okay that's all we're going to talk

okay that's all we're going to talk about for this for now since we've

about for this for now since we've already covered it earlier in the course

already covered it earlier in the course now i'm going to go into more detail

now i'm going to go into more detail about lists lists are an essential

about lists lists are an essential python data structure and so an example

python data structure and so an example of a list would be let's create a list

of a list would be let's create a list called dogs so we're going to create

called dogs so we're going to create the dog names we have roger we have sid

the dog names we have roger we have sid and this allows you to group together

and this allows you to group together multiple values and reference them all

multiple values and reference them all with a common name so we have a list of

with a common name so we have a list of dogs and this is just two strings so the

dogs and this is just two strings so the list always going to have the opening

list always going to have the opening closing brackets and each item in the

closing brackets and each item in the list is going to be separated with a

list is going to be separated with a comma and a list can hold different

comma and a list can hold different types of values so these are all strings

types of values so these are all strings but we can

but we can have a string

have a string an integer a string a

an integer a string a boolean

boolean and you can mix different types of data

and you can mix different types of data types

types in a single list

in a single list and then you can check if an item is

and then you can check if an item is contained in a list with the in operator

contained in a list with the in operator so we talked about the in operator

so we talked about the in operator earlier but let me show you how that

earlier but let me show you how that works so we're going to print here's

works so we're going to print here's where we can use the in operator we're

where we can use the in operator we're going to check if roger

going to check if roger is

is in

in dogs

dogs so let's see

so let's see so run that true but now let's check if

so run that true but now let's check if bo is in dogs well

bo is in dogs well false because it's checking

false because it's checking so this is how you can check if an item

so this is how you can check if an item is in a list

is in a list you can also define a list as an empty

you can also define a list as an empty string so i could actually just

string so i could actually just remove all this and now we just have an

remove all this and now we just have an empty list and this is obviously still

empty list and this is obviously still going to be false because there's

going to be false because there's nothing in that list

nothing in that list but let's go back to when we had some

but let's go back to when we had some items in the list

items in the list and you can reference items in a list by

and you can reference items in a list by their indexes starting with zero so i'm

their indexes starting with zero so i'm going to do dogs and then i can use

going to do dogs and then i can use these brackets so and now i'm going to

these brackets so and now i'm going to put the so this is where we're going to

put the so this is where we're going to reference the thing

reference the thing an item from the list and i'm going to

an item from the list and i'm going to type in 0 which will be this item right

type in 0 which will be this item right here roger or i could put 2 and it's

here roger or i could put 2 and it's going to do 0 1 2 and now we're going to

going to do 0 1 2 and now we're going to have sid

have sid and the same

and the same and you can use this same notation to

and you can use this same notation to update an item

update an item in a list so i'm going to add another

in a list so i'm going to add another line of code here and put dogs 2 is

line of code here and put dogs 2 is going to equal

bo and now i'm just going to print the

and now i'm just going to print the entire list here and now

entire list here and now instead of

instead of being roger 1 said true to roger 1 bow

being roger 1 said true to roger 1 bow true

true because we've updated the item at index

because we've updated the item at index 2 to be bo instead of sid

now you can also use the index method so

so um instead of

um instead of like if i want to find the first item in

like if i want to find the first item in the list i could do it like this

the list i could do it like this so you can also use a negative number

so you can also use a negative number here

here just how we saw on the string so

just how we saw on the string so negative 2 is going to start with one

negative 2 is going to start with one two

two actually let's do negative one so it

actually let's do negative one so it should return true here

should return true here okay true so it starts with this one if

okay true so it starts with this one if you put a negative number

you put a negative number you can also extract part of a list now

you can also extract part of a list now this is very similar to what we showed

this is very similar to what we showed using

using with the string let me just add another

with the string let me just add another item here

item here [Music]

[Music] now i am going to

now i am going to use the colon to do part of a list so

use the colon to do part of a list so i'm going to 2

i'm going to 2 4

4 and so this is a slice

and so this is a slice so it's going to start at the second or

so it's going to start at the second or zero

zero one

two which is now bow because we change it to

which is now bow because we change it to bow and it's going to go through four

bow and it's going to go through four it's going to go through four but not

it's going to go through four but not over pat not including four so it's

over pat not including four so it's going to be 2

going to be 2 3

3 and then not 4 so it's just sid and true

and then not 4 so it's just sid and true or bow and true because we updated 2 to

or bow and true because we updated 2 to bow

bow and you can also just leave this blank

and you can also just leave this blank so it's going to go through the end of

so it's going to go through the end of the list or if you

the list or if you leave the first number blank

leave the first number blank it's going to go it's going to start at

it's going to go it's going to start at the beginning of the list and we can go

the beginning of the list and we can go through for instance index three

through for instance index three and so that's a way to slice the list

and so that's a way to slice the list you can also

you can also use the the length function so let's

use the the length function so let's find out how many items are in the list

find out how many items are in the list i'll use the length the length of dogs

i'll use the length the length of dogs is six or six items in the list we can

is six or six items in the list we can also add items to the list by using the

also add items to the list by using the append method so i'm going to do dogs

append method so i'm going to do dogs dot append

dot append and then i can

and then i can add an item so i can say something like

add an item so i can say something like judah and now if we see the length

judah and now if we see the length there's now going to be 7 and if we just

there's now going to be 7 and if we just print

print the full list

the full list then we can see that we can see all the

then we can see that we can see all the items including the one that was just

items including the one that was just added we can also use the extend method

added we can also use the extend method the extend is another way to add an item

the extend is another way to add an item to a list so if i do instead of dogs

to a list so if i do instead of dogs append i can do dogs that extend

append i can do dogs that extend and then i'm going to pass in

and then i'm going to pass in instead of just passing in the string

instead of just passing in the string i'm gonna pass in

i'm gonna pass in the item as a list so i'm gonna and it's

the item as a list so i'm gonna and it's gonna add it just the same but now i can

gonna add it just the same but now i can actually

actually combine two lists together so i'm gonna

combine two lists together so i'm gonna put a five so if i do this we can see

put a five so if i do this we can see now we are taking this list and

now we are taking this list and extending it by adding this list on the

extending it by adding this list on the end this is a two item list and we have

end this is a two item list and we have that six m list and now we have the

that six m list and now we have the eight item list

eight item list you can also use the

you can also use the plus equals operator so

plus equals operator so to use the plus equals operator i'm

to use the plus equals operator i'm going to do dogs it's the same it's

going to do dogs it's the same it's going to do the same thing as extend

going to do the same thing as extend so plus equals

so plus equals and then we have this list take this

and then we have this list take this parentheses off here and it should look

parentheses off here and it should look exactly the same see it's showing up the

exactly the same see it's showing up the same thing up here

same thing up here so the plus equals is going to be the

so the plus equals is going to be the same thing as extend where it takes the

same thing as extend where it takes the list that's already exists and adds this

list that's already exists and adds this other list to the end

other list to the end and when you're using the extend or the

and when you're using the extend or the plus equals

plus equals you don't want to forget the square

you don't want to forget the square brackets

brackets here so if you if you forget the square

here so if you if you forget the square brackets and let's say i'm just going to

brackets and let's say i'm just going to add this iron to the list

add this iron to the list it's now actually going to put each

it's now actually going to put each letter individually here

letter individually here so if i you can kind of see it better if

so if i you can kind of see it better if i move over here

i move over here so it so that so you want to make sure

so it so that so you want to make sure you put the the brackets

you put the the brackets and another thing you can do is remove

and another thing you can do is remove you can remove an item using the remove

you can remove an item using the remove method so i'm gonna do

method so i'm gonna do dogs dot remove

dogs dot remove sid

sid okay now i'm gonna play it here and

okay now i'm gonna play it here and it's saying

oh obviously um i'm moving sid but we've already changed the element of sid to

already changed the element of sid to bow so let's remove

bow so let's remove quincy and let's try that

quincy and let's try that okay so now there's no quincy

okay so now there's no quincy so another common thing to do another

so another common thing to do another common list method is pop so if i do

common list method is pop so if i do dogs.pop

dogs.pop it's going to remove and return a single

it's going to remove and return a single item so first i'm going to

item so first i'm going to [Music]

[Music] do dot

do dot print dogs that pop and then i'm going

print dogs that pop and then i'm going to print dog so if i

to print dog so if i so first it's going to return 5 that was

so first it's going to return 5 that was the last item that we added onto the

the last item that we added onto the list and now when i print the list that

list and now when i print the list that item's not in the list so pop is going

item's not in the list so pop is going to remove the last item from the list

to remove the last item from the list and it's going to return the last item

and it's going to return the last item it's going to return and remove the last

it's going to return and remove the last item from the list and then it's not on

item from the list and then it's not on the list anymore

the list anymore now let's make this

now let's make this let's let's simplify this just go back

let's let's simplify this just go back to the initial list and i'm going to

to the initial list and i'm going to change this to items

change this to items now i'm going to show you how to add an

now i'm going to show you how to add an item in the middle of the list at a

item in the middle of the list at a specific index you can use the insert

specific index you can use the insert method so i'm going to do items dot

method so i'm going to do items dot insert

insert i'm going to put the index which is

i'm going to put the index which is going we're going to insert at the index

going we're going to insert at the index number two and the item is going to be

number two and the item is going to be test

test and then i'm just going to print that

and then i'm just going to print that print

print items

items and then i'll run that and then we can

and then i'll run that and then we can see it index number two we now see the

see it index number two we now see the item test

item test now to add multiple items at a specific

now to add multiple items at a specific index you need to use slices so

index you need to use slices so let me show you how you do that so we're

let me show you how you do that so we're going to do a slice

and i'm going to set that equal to test

test 1

test 2.

2. we print that

we print that so now you can see we have test 1 and

so now you can see we have test 1 and test 2 right here

test 2 right here right behind this search thing here

right behind this search thing here and we've inserted multiple items into

and we've inserted multiple items into the list starting at index 1.

the list starting at index 1. now you can also sort a list

now you can also sort a list so if i do

so if i do here we go um

here we go um items dot sort

items dot sort it will sort the list

but you have to make sure okay we have an error it's not supported between

an error it's not supported between we have a combination of ins and strings

we have a combination of ins and strings so let's

so let's make it so it's all strings in the list

and then it should

then it should be able to sort it

okay now the

now the strings are in alphabetical order and if

strings are in alphabetical order and if we're using integers or floats and they

we're using integers or floats and they would just be in numerical order

would just be in numerical order now one thing that's interesting about

now one thing that's interesting about that if i put change this to

that if i put change this to bow

bow you'll see now we have this at the

you'll see now we have this at the beginning and this at the end

beginning and this at the end so

so a the sort method orders uppercase

a the sort method orders uppercase letters first and then lowercase letters

letters first and then lowercase letters so to fix that actually to make it

so to fix that actually to make it make more sense we're going to change

make more sense we're going to change that to

that to bob and to fix that

bob and to fix that within the sort i'm going to i'm going

within the sort i'm going to i'm going to put key equals str dot lower

and now it's going to sort these correctly how

it's going to sort these correctly how you would imagine not caring about

you would imagine not caring about uppercase or lowercase letters

uppercase or lowercase letters sorting modifies the original list

sorting modifies the original list content so to avoid that you can copy

content so to avoid that you can copy the list content using

the list content using so let me show you if we do

items items

copy equals

equals items

items and then we make a slice

and then we make a slice with with nothing at the beginning and

with with nothing at the beginning and nothing at the end so it's going to

nothing at the end so it's going to start at the beginning of the list to

start at the beginning of the list to the end of the list and now we can have

the end of the list and now we can have a copy and i can print

a copy and i can print items copy

items copy so if i print that so now we see we have

so if i print that so now we see we have the sorted list that's that we ran the

the sorted list that's that we ran the sort on but we also still have

sort on but we also still have the original list

so it with all the words in the original order

and there is also a way to sort a list without returning a

without returning a new list

new list there is also a way to sort a list

there is also a way to sort a list without modifying the original list so

without modifying the original list so instead of copying a list

instead of copying a list um what i'm going to do

um what i'm going to do is

is i items

i items instead of doing items dot sort

instead of doing items dot sort we are going to do

we are going to do we're going to use a global function

we're going to use a global function called sorted

called sorted so in the sorted function

so in the sorted function we are going to pass in two parameters

we are going to pass in two parameters so first is the list items

and then the second is how we're sorting it so this just makes

it so this just makes sure that the key the case of the

sure that the key the case of the letters don't matter and then i'm just

letters don't matter and then i'm just going to print that

now if i run this you can see we it we print printed the sorted list

we print printed the sorted list and now we're printing the list and it's

and now we're printing the list and it's not it's no longer sorted because this

not it's no longer sorted because this creates a new list without modifying the

creates a new list without modifying the original list

original list okay now let's learn about another data

okay now let's learn about another data structure called

structure called couples

couples so

so this time i'm going to put

this time i'm going to put tuples

tuples so we're using a comment here so tuples

so we're using a comment here so tuples are another fundamental python data

are another fundamental python data structure they allow you to create

structure they allow you to create immutable groups of objects this means

immutable groups of objects this means that once a tuple is created it cannot

that once a tuple is created it cannot be modified so we already saw that we

be modified so we already saw that we could modify lists but tuple you can't

could modify lists but tuple you can't even add or remove items

even add or remove items they're created in a way similar to

they're created in a way similar to lists but using parentheses instead of

lists but using parentheses instead of square brackets so

square brackets so for instance i'm going to do names

for instance i'm going to do names equals instead of using square brackets

equals instead of using square brackets we're going to do parentheses roger

we're going to do parentheses roger and

and sid

sid okay so a tuple's order like a list so

okay so a tuple's order like a list so you can get its values by referencing an

you can get its values by referencing an index

index an index so i could say for instance

an index so i could say for instance names and if i do the bracket i could

names and if i do the bracket i could put a zero here to return

put a zero here to return roger

roger and then you can also use the index

and then you can also use the index method for instance names

method for instance names dot

dot index

index and then i can

and then i can pass in something like

pass in something like roger and then this is going to

roger and then this is going to return 0

return 0 because it's going to get the the index

because it's going to get the the index number of that so as with strings and

number of that so as with strings and lists using a negative index we'll start

lists using a negative index we'll start searching from the end so i could do

that i can do negative one to start not negative zero negative one to start

not negative zero negative one to start searching from the end here

searching from the end here and you can count the items in a tuple

and you can count the items in a tuple with the length function so i could do

with the length function so i could do if i do length and then do names it's if

if i do length and then do names it's if i printed that it would just print 2

i printed that it would just print 2 because there are two items in that

because there are two items in that tuple

tuple then you can also check if an item is

then you can also check if an item is contained in a tuple with the in

contained in a tuple with the in operators very similar to a list so i

operators very similar to a list so i can do this time i will print it i'll do

can do this time i will print it i'll do print

print roger

roger in

in names so if i print that and run it

names so if i print that and run it we'll see true because roger is in the

we'll see true because roger is in the names

names and then you can extract part of a tuple

and then you can extract part of a tuple using slices

using slices just like we could do with with strings

just like we could do with with strings and lists so i could do names and then i

and lists so i could do names and then i could do

could do 0 starting at the whoops

0 starting at the whoops 0

0 2

2 so that's just going to start at the

so that's just going to start at the zero index and be done at the index 2

zero index and be done at the index 2 and then

and then and then you can use the so you can get

and then you can use the so you can get a sorted version of the tuple using the

a sorted version of the tuple using the sorted global function so

sorted global function so remember when we were looking at lists

remember when we were looking at lists when we used the sorted function it

when we used the sorted function it created a new a new list or so when

created a new a new list or so when we're creating using the sorted function

we're creating using the sorted function for tuples it creates a new tuple so i

for tuples it creates a new tuple so i can say sorted

can say sorted [Music]

[Music] names

names and this would put them in alphabetical

and this would put them in alphabetical order they already in are in

order they already in are in alphabetical order but say there is one

alphabetical order but say there is one more

more word in this list

word in this list and then

and then i can print this

i can print this [Music]

[Music] to print the sorted version but it's not

to print the sorted version but it's not actually going to modify the list

actually going to modify the list because you cannot modify

because you cannot modify a tuple

a tuple and then you can create a new tuple from

and then you can create a new tuple from existing tuples using the plus operator

existing tuples using the plus operator so i could say something like

so i could say something like new tuple

new tuple [Music]

[Music] equals names and then i can use the plus

equals names and then i can use the plus operator

operator and then i would say i would just say

and then i would say i would just say tina

tina and

and quincy i could add a few i could add so

quincy i could add a few i could add so these will combine two tuples into a new

these will combine two tuples into a new tuple but you can never like i said you

tuple but you can never like i said you can't actually modify the original tuple

can't actually modify the original tuple now let's learn about dictionaries

now let's learn about dictionaries dictionaries are another very important

dictionaries are another very important python data structure

python data structure while lists allow you to create

while lists allow you to create collections of values dictionaries allow

collections of values dictionaries allow you to create key value pairs we already

you to create key value pairs we already discussed dictionaries a little bit but

discussed dictionaries a little bit but now we're going to discuss even more

now we're going to discuss even more about dictionaries so let me give you an

about dictionaries so let me give you an example of a dictionary with just one

example of a dictionary with just one key value pair so dog equals and then

key value pair so dog equals and then we're going to use the curly braces to

we're going to use the curly braces to create the dictionary and i'll put name

create the dictionary and i'll put name and then i will put

and then i will put roger and just like any type of strings

roger and just like any type of strings we could make these single quotes or

we could make these single quotes or they could be double quotes and the

they could be double quotes and the spaces here are not very important but

spaces here are not very important but it's common to put spaces in between

it's common to put spaces in between these things for better readability

these things for better readability and the key can be any immutable

and the key can be any immutable value so this is the key this is the

value so this is the key this is the value and the key can be any immutable

value and the key can be any immutable value

value such as a string a number or a tuple

such as a string a number or a tuple the value can be anything you want so a

the value can be anything you want so a dictionary can contain multiple key

dictionary can contain multiple key value pairs so like for instance we got

value pairs so like for instance we got the name we can have

the name we can have age

age and that's going to be

8. and you can access individual key values using the notation like this so i

values using the notation like this so i can say

can say dog

dog so i'm using the bracket notation i can

so i'm using the bracket notation i can do name so if i print this it's just

do name so if i print this it's just going to

going to print roger

and then again i can use the single quotes 2 if i want

quotes 2 if i want and it still prints roger

and it still prints roger and then you can use the same notation

and then you can use the same notation to change the value stored at a specific

to change the value stored at a specific index

index so let's say i want to change the name

so let's say i want to change the name so if i do dog

so if i do dog and i'm going to say that the name

and i'm going to say that the name is now going to equal

is now going to equal sid

sid now i'm just going to print the whole

now i'm just going to print the whole the whole thing

the whole thing and we can see the name is now sid

and we can see the name is now sid instead of roger

instead of roger so another way to get a specific element

so another way to get a specific element is to use the get method so if i do a

is to use the get method so if i do a dog dot

dog dot get

get and then i

and then i do name so i'm going to try to get the

do name so i'm going to try to get the name here

name here it's going to return roger so

it's going to return roger so one good thing about this is that you

one good thing about this is that you can add a default value like let's say

can add a default value like let's say i'm going i'm searching for color

i'm going i'm searching for color and it's saying none it's giving it none

and it's saying none it's giving it none because there is no color

because there is no color but what if i want a default value so

but what if i want a default value so i'm going to put comma and then i'll put

i'm going to put comma and then i'll put brown

so now if it cannot find the color in the dictionary it's going to return

the dictionary it's going to return brown but if it can find the color like

brown but if it can find the color like let's say

let's say color

color and this is a

and this is a green dog

green dog okay we'll return

okay we'll return green

green so with the bracket notation that was

so with the bracket notation that was showing you earlier you cannot have a

showing you earlier you cannot have a default value so that's one good thing

default value so that's one good thing about the get method

about the get method now you can also use the pop method to

now you can also use the pop method to retrieve the value of a key and delete

retrieve the value of a key and delete the item from the dictionary we also

the item from the dictionary we also showed the pop method for lists so for

showed the pop method for lists so for instance i can say

instance i can say get dot

get dot pop

pop and then i will pass in

and then i will pass in name

name and then right after that i'm just going

and then right after that i'm just going to print

dog that the the whole dictionary so first we're going to get roger and then

first we're going to get roger and then when i print the dictionary here it's

when i print the dictionary here it's not going to show roger anymore because

not going to show roger anymore because we we deleted it pop will return the

we we deleted it pop will return the item and delete the item

item and delete the item now you can also use a function a method

now you can also use a function a method called pop item the pop item method well

called pop item the pop item method well let me show you that one pop item

let me show you that one pop item it's going to retrieve and remove the

it's going to retrieve and remove the last key value pair inserted into the

last key value pair inserted into the dictionary

dictionary so

so in this case it should be color so if i

in this case it should be color so if i run this

run this it's going to return color green and now

it's going to return color green and now when i print out the dictionary it's not

when i print out the dictionary it's not going to show color green because that

going to show color green because that was already removed it removed the last

was already removed it removed the last item

item you can also check if a key is contained

you can also check if a key is contained in a dictionary by using the in operator

in a dictionary by using the in operator so we're going to say we're going to try

so we're going to say we're going to try to find out if

color is in

is in dog if there's a key called color in dog

dog if there's a key called color in dog we run that and it says

we run that and it says true another thing we can do is get a

true another thing we can do is get a list with the keys in the dictionary

list with the keys in the dictionary using the keys method so if i do dog dot

using the keys method so if i do dog dot keys

keys and then we'll run that it's going to

and then we'll run that it's going to show the keys so the keys are name age

show the keys so the keys are name age and

and color

color we can see that it's inside the thing

we can see that it's inside the thing called dick keys but we can also pass

called dick keys but we can also pass this into list so we return an actual

this into list so we return an actual just the list part so now we can see

just the list part so now we can see it's just an actual list name age and

it's just an actual list name age and color

color then we can do the same thing with

then we can do the same thing with values so

values so instead of dog.keys let's do

instead of dog.keys let's do values

values print that

print that and you can see we have roger 8 green we

and you can see we have roger 8 green we can pass it into a list

can pass it into a list to

to return the app just the list here

return the app just the list here roger 8 green

roger 8 green and then finally if we just do items

and then finally if we just do items [Music]

[Music] it's going to return all the items in

it's going to return all the items in the list or all the items in the

the list or all the items in the dictionary

dictionary and convert it into a list

so you can see this is the first item in the list this

this is the first item in the list this is the second item and then we have the

is the second item and then we have the third item here so

third item here so we can see each item of the list each

we can see each item of the list each item of the dictionary is now in a list

item of the dictionary is now in a list and then like a lot of the other things

and then like a lot of the other things we can use the length function and i'll

we can use the length function and i'll just put dog

and we can see that there are three items in dog now you can also add a new

items in dog now you can also add a new key value pair to the dictionary so

key value pair to the dictionary so let's say i want to do

let's say i want to do dog

food or i it doesn't even have to be a single

or i it doesn't even have to be a single word i could put favorite

word i could put favorite food

food and i'm going to say

and i'm going to say meet

meet and now we're going to print

and now we're going to print that

let's see what do we oh this was supposed to i did that a little

this was supposed to i did that a little wrong

there we go this is actually how you do it you put use the bracket notation

it you put use the bracket notation equals and let's put what it equals

equals and let's put what it equals there okay now you can see that we now

there okay now you can see that we now have a new item on the list favorite

have a new item on the list favorite food

food meet

meet then you can also delete an item from a

then you can also delete an item from a list or a delete a key value pair so i'm

list or a delete a key value pair so i'm going to d e l means delete dog

going to d e l means delete dog or

or dog there we go and this time i'm going

dog there we go and this time i'm going to delete

to delete color and i'm just going to use single

color and i'm just going to use single quotes instead of double quotes to show

quotes instead of double quotes to show you that doesn't really matter the type

you that doesn't really matter the type of quote and now you can see we don't

of quote and now you can see we don't know what color

know what color this dog is it's no longer a green dog

this dog is it's no longer a green dog and then you can also copy a dictionary

and then you can also copy a dictionary so if you want to make two copies of a

so if you want to make two copies of a dictionary you can do

dictionary you can do do like this dog copy that's the name of

do like this dog copy that's the name of the new dictionary i'll do dog dot copy

the new dictionary i'll do dog dot copy and that would be the new

and that would be the new copied version of the dictionary

copied version of the dictionary okay now we are going to talk about a

okay now we are going to talk about a new thing called sets

new thing called sets sets are another important python data

sets are another important python data structure

structure sets kind of work like tuples but

sets kind of work like tuples but they're not ordered and they are

they're not ordered and they are immutable so you can change them

immutable so you can change them you can also say that they kind of work

you can also say that they kind of work like dictionaries but they don't have

like dictionaries but they don't have keys

keys they're all they have an immutable

they're all they have an immutable version of a set called a frozen set so

version of a set called a frozen set so let me show you how you would create a

let me show you how you would create a set so let's do names

set so let's do names and you we're going to use

and you we're going to use curly brackets just like that

curly brackets just like that and

and just like that so we have two names so

just like that so we have two names so you can see the differences the a

you can see the differences the a dictionary

dictionary you use the curly brackets but there's

you use the curly brackets but there's going to be key value pairs but this

going to be key value pairs but this doesn't have key value pairs in a list

doesn't have key value pairs in a list it's just going to be a

it's just going to be a item after item like this but there's

item after item like this but there's going to be brackets instead of curly

going to be brackets instead of curly braces

braces so

so one thing about the sets is that they

one thing about the sets is that they are not ordered

are not ordered so sets work well when you think about

so sets work well when you think about them as mathematical sets

them as mathematical sets so for instance let's have we're going

so for instance let's have we're going to create a set 1

to create a set 1 with roger and sid and we're going to

with roger and sid and we're going to have a set

have a set 2

2 which is just going to have

which is just going to have roger

roger and so you can intersect two sets so

and so you can intersect two sets so uh the inner intersect

the intersection of these two sets will be set one

be set one and

and set

set two so if i just print that out print

two so if i just print that out print intersect

intersect and then we can just run that and we're

and then we can just run that and we're gonna see what so it's just roger so the

gonna see what so it's just roger so the intersection of these two sets are just

intersection of these two sets are just roger the all the items that they have

roger the all the items that they have in common you can also create a union of

in common you can also create a union of two sets so

two sets so instead of just calling this union i'll

instead of just calling this union i'll put

put mod for modification and so i can show a

mod for modification and so i can show a few different things with the same

few different things with the same variable name and the union symbol is

variable name and the union symbol is just the

just the straight line like this it's not an i

straight line like this it's not an i it's just the

it's just the straight line

straight line it's on the same key as a

it's on the same key as a as the was it the forward slash

as the was it the forward slash backslash one of the slashes

backslash one of the slashes now we're going to get every single item

now we're going to get every single item in both sets which happens to in this

in both sets which happens to in this case just happen to be the same as set

case just happen to be the same as set one but if we change this one to the

one but if we change this one to the word luna it's just a different name and

word luna it's just a different name and now we're going to get each item

now we're going to get each item in both sets or said luna roger for the

in both sets or said luna roger for the intersection and then we can also get

intersection and then we can also get the difference the difference between

the difference the difference between two sets so let me change this to back

two sets so let me change this to back to roger and for the difference between

to roger and for the difference between two sets i'll use a the minus

two sets i'll use a the minus and

and the difference is just going to be sid

the difference is just going to be sid that's the only thing that's different

that's the only thing that's different between the two sets

between the two sets you can also check if a set is a

you can also check if a set is a superset of another and if a set is a

superset of another and if a set is a subset of another so how you would do

subset of another so how you would do that is

that is so we're just saying like is this

so we're just saying like is this greater than that which means it has

greater than that which means it has everything of the in the other set true

everything of the in the other set true now if we put the other direction

now if we put the other direction is does this set have everything in this

is does this set have everything in this one no it doesn't

one no it doesn't you can also count items in a set with

you can also count items in a set with the length function that's pretty

the length function that's pretty self-explanatory i won't even show it to

self-explanatory i won't even show it to you we've seen the link function so many

you we've seen the link function so many times

times you can also get you can also get a list

you can also get you can also get a list from the items in a set by passing the

from the items in a set by passing the set to the list constructor so

set to the list constructor so i'm just going to remove this

i'm just going to remove this and we will do

and we will do list

list set

set one

one okay so now we have a list of the set

okay so now we have a list of the set and then you can check if an item is

and then you can check if an item is contained in a set with the in operator

contained in a set with the in operator just like the

just like the list and the other way we the other

list and the other way we the other places we use the in operator and then

places we use the in operator and then one more final thing about a set a set

one more final thing about a set a set cannot have two of the same item so

cannot have two of the same item so that's another thing that's useful about

that's another thing that's useful about sets so if i type in rogers now we have

sets so if i type in rogers now we have roger sid roger if i play this we'll see

roger sid roger if i play this we'll see it's only going to

it's only going to print sid roger it's not going to add

print sid roger it's not going to add the roger twice to the set

the roger twice to the set so that's another

so that's another useful thing about sets is that make

useful thing about sets is that make sure there's only one of each item in

sure there's only one of each item in the the set so if you have a list that

the the set so if you have a list that has multiple items you can convert it to

has multiple items you can convert it to a set

a set um and then i'll just make sure there's

um and then i'll just make sure there's only one of each thing in that set

only one of each thing in that set now let's talk more about functions

now let's talk more about functions we already talked about functions in the

we already talked about functions in the last section but we're going to do a

last section but we're going to do a review and then go into even more detail

review and then go into even more detail about functions so a function lets us

about functions so a function lets us create a set of instructions that we can

create a set of instructions that we can run when needed and i'm just going to

run when needed and i'm just going to paste in a function and again the

paste in a function and again the indentation it can be either four spaces

indentation it can be either four spaces two spaces

two spaces as long as it's indented the exact same

as long as it's indented the exact same amount

amount so functions are essential in python and

so functions are essential in python and in many other programming languages they

in many other programming languages they help us create meaningful programs

help us create meaningful programs because they allow us to decompose a

because they allow us to decompose a program into manageable parts and they

program into manageable parts and they promote readability and code reuse

promote readability and code reuse so this one is a function called hello

so this one is a function called hello that just prints hello this is the

that just prints hello this is the function definition

function definition so there's a name called hello this is

so there's a name called hello this is the name here and then the body of the

the name here and then the body of the function

function which is the the set of instructions

which is the the set of instructions and the body of the function is

and the body of the function is everything that's after the colon

everything that's after the colon and everything that's indented one level

and everything that's indented one level on the right

on the right so to run this function we must call it

so to run this function we must call it so i can just type in hello

so i can just type in hello hello

hello and then this is the syntax to to call

and then this is the syntax to to call the function and i can call it multiple

the function and i can call it multiple times so i can just copy this and paste

times so i can just copy this and paste it and now if i just run this program

it and now if i just run this program it's going to print hello

it's going to print hello three times

three times the name of the function is very

the name of the function is very important so the name of the function is

important so the name of the function is hello it should be the function name

hello it should be the function name should be descriptive so anyone calling

should be descriptive so anyone calling it can imagine what the function does

it can imagine what the function does a function can accept one or more

a function can accept one or more parameters this is something else that

parameters this is something else that we saw

we saw before

before but

but i can type in a parameter right here and

i can type in a parameter right here and this becomes a variable that we can use

this becomes a variable that we can use in the function so i can change this

in the function so i can change this instead of printing hello

instead of printing hello it's going to print hello

it's going to print hello and then we'll just put name

and then we'll just put name and now i can call the function with the

and now i can call the function with the name

and i can actually um call it with different names so we'll do bow

different names so we'll do bow and we'll do

and we'll do quincy

quincy and then if i just play that we see

and then if i just play that we see hello bo

hello bo hello quincy

hello quincy so

so as you can see we call the function by

as you can see we call the function by passing the argument

passing the argument and again you can use single quote or

and again you can use single quote or double quotes here it's better to be

double quotes here it's better to be consistent just always use single quotes

consistent just always use single quotes or always use double quotes

or always use double quotes but for teaching i like to switch it up

but for teaching i like to switch it up to just to emphasize that you can use

to just to emphasize that you can use either so let me tell you about the

either so let me tell you about the difference between parameters and

difference between parameters and arguments

arguments these two words parameters and arguments

these two words parameters and arguments are sometimes used interchangeably

are sometimes used interchangeably and it's common to get confused about

and it's common to get confused about the distinction

the distinction we call

we call parameters

parameters the values accepted by the function

the values accepted by the function inside the function definition

inside the function definition and arguments are the values we pass to

and arguments are the values we pass to the function when we call it also an

the function when we call it also an argument can have a default value

argument can have a default value that's applied if the argument is not

that's applied if the argument is not specified so let me show you how i would

specified so let me show you how i would do that so we have it name so right now

do that so we have it name so right now it always needs to be get a name well

it always needs to be get a name well first let me show you what would happen

first let me show you what would happen if i called the function without passing

if i called the function without passing the name

the name i'm just going to run that and we can

i'm just going to run that and we can see we're going to get an error hello

see we're going to get an error hello missing one required positional argument

missing one required positional argument name but we can make it so you can call

name but we can make it so you can call this function without passing in a name

this function without passing in a name where it's optional you can't if you

where it's optional you can't if you want so i'm going to put an equal sign

want so i'm going to put an equal sign and then i'm gonna type in my friend

and then i'm gonna type in my friend and just to make consistent make this

and just to make consistent make this consistent i'm gonna make this all

consistent i'm gonna make this all double quotes

okay so this is now an optional argument so it's it's you can pass in the name

so it's it's you can pass in the name but if you don't pass a name it's going

but if you don't pass a name it's going to default to my friend so i'll just run

to default to my friend so i'll just run this again with that default

this again with that default value and now it's hello bow hill quincy

value and now it's hello bow hill quincy hello my friend because we called this

hello my friend because we called this and we didn't specify any argument or

and we didn't specify any argument or parameter and then we can also accept

parameter and then we can also accept multiple parameters so i'm just going to

multiple parameters so i'm just going to get rid of this default value and i'll

get rid of this default value and i'll put 8 so now we're accepting a name and

put 8 so now we're accepting a name and an age so we can now use both parameters

an age so we can now use both parameters in our function so i can do plus

in our function so i can do plus hello

hello name

name [Music]

[Music] you are

you are and we're going to add

and we're going to add the age

the age and now it's going to be passed in as a

and now it's going to be passed in as a number but we're going to convert it to

number but we're going to convert it to a string

a string so you are

so you are [Music]

[Music] years old

years old and then we have to make sure we have to

and then we have to make sure we have to make sure to add a space in here so

make sure to add a space in here so there'll be a space space after this

there'll be a space space after this word then the number then a space and

word then the number then a space and then years old

then years old so i'm gonna now have to pass in the

so i'm gonna now have to pass in the number

number and now i can run this function

and now i can run this function now showing the red

now showing the red squiggly lines

squiggly lines i sometimes the the red squiggly lines

i sometimes the the red squiggly lines will appear when it's

will appear when it's actually correct

actually correct so let me what am i am i doing something

so let me what am i am i doing something wrong here

wrong here oh i need to put the parentheses

oh i need to put the parentheses if the red squiggly lines appears when

if the red squiggly lines appears when it's actually correct they'll it they'll

it's actually correct they'll it they'll go away

go away usually within a few seconds or if you

usually within a few seconds or if you hit enter

hit enter so that actually was a problem i forgot

so that actually was a problem i forgot the parentheses at the end um so

the parentheses at the end um so you can see this is what the whole

you can see this is what the whole function looks like

function looks like if it's all on one line but i'm just

if it's all on one line but i'm just going to

going to move that over so hello bo you are 39

move that over so hello bo you are 39 years old so we've used the name and the

years old so we've used the name and the age

age so parameters are passed by reference

so parameters are passed by reference all types in python are objects but some

all types in python are objects but some of them are immutable including integers

of them are immutable including integers booleans floats strings and tuples this

booleans floats strings and tuples this means that if you pass them as

means that if you pass them as parameters and you modify their value

parameters and you modify their value inside the function the new value is not

inside the function the new value is not reflected outside of the function

reflected outside of the function let me just give you an example of that

let me just give you an example of that so if i just i'm just going to paste in

so if i just i'm just going to paste in some new code here and we can see we

some new code here and we can see we have this function called change and

have this function called change and we're going to pass in this value if we

we're going to pass in this value if we pass in this this valve variable 1 to

pass in this this valve variable 1 to the change function and we set value to

the change function and we set value to 2

2 well then we're going to print the value

well then we're going to print the value and see what happens

and see what happens and you can see it's now just 1 here so

and you can see it's now just 1 here so so it didn't change the value

so it didn't change the value the value so what we change inside the

the value so what we change inside the function doesn't affect anything from

function doesn't affect anything from outside the function

outside the function and then you can see we have these

and then you can see we have these orange squiggly lines here local

orange squiggly lines here local variable value is assigned but never

variable value is assigned but never used it's just showing that actually

used it's just showing that actually this isn't really doing anything once

this isn't really doing anything once it's inside the function and we change

it's inside the function and we change it doesn't change anything outside the

it doesn't change anything outside the function

function so if you pass an object that's not

so if you pass an object that's not immutable you do change one of its

immutable you do change one of its properties and the change will be

properties and the change will be reflected outside so this was

reflected outside so this was mutable this is immutable an object that

mutable this is immutable an object that would be

would be mutable would be like a dictionary so if

mutable would be like a dictionary so if i change this to a dictionary and i put

i change this to a dictionary and i put name

and i set it to bow but then inside the change i do value

but then inside the change i do value dot name or not i'll put the the

dot name or not i'll put the the brackets value name

brackets value name so the key of this dictionary and i set

so the key of this dictionary and i set that to sid

that to sid and i run this we'll see now the name

and i run this we'll see now the name has changed to sin so we changed we use

has changed to sin so we changed we use the change function to change name to

the change function to change name to sid and now it actually is changed

sid and now it actually is changed because a dictionary is mutable

because a dictionary is mutable so a function can also return a value

so a function can also return a value using the return statement

using the return statement so i'm going to update this whole thing

so i'm going to update this whole thing and talk about return statements a

and talk about return statements a function can return a value using the

function can return a value using the return statement so it's going to return

return statement so it's going to return this name that we then can continue to

this name that we then can continue to use in our in our program it doesn't

use in our in our program it doesn't have to return name it can return

have to return name it can return anything that happens inside the

anything that happens inside the function

function and

and the when the function meets the return

the when the function meets the return statement the function ends so you can

statement the function ends so you can have a return statement have code after

have a return statement have code after it but it will just end like for

it but it will just end like for instance if you have the return

instance if you have the return statement in a conditional like in an if

statement in a conditional like in an if statement we can also omit

statement we can also omit the return the return value

the return the return value so it's just going to end the function

so it's just going to end the function and not return anything so i had

and not return anything so i had mentioned having the return statement in

mentioned having the return statement in a conditional so that's a common way to

a conditional so that's a common way to end a function if the starting condition

end a function if the starting condition is not met

is not met like for instance if we update the

like for instance if we update the function to

function to this so if not name return this so if i

this so if not name return this so if i mean if not name return

mean if not name return or

or else

else you don't even need an else because this

you don't even need an else because this will just in the function and you don't

will just in the function and you don't even need an else this will happen if

even need an else this will happen if there is a name now we just said that

there is a name now we just said that you have to pass in something if you

you have to pass in something if you don't have a default value so the way to

don't have a default value so the way to get to that would just be to call the

get to that would just be to call the function

function with false

with false so if we call with false then it's just

so if we call with false then it's just going to return it doesn't do anything

going to return it doesn't do anything but if we call it with

but if we call it with bo

bo then let's see

then let's see hello bo so you can also return multiple

hello bo so you can also return multiple values by using comma separated values

values by using comma separated values so

so for instance i can i'm just going to

for instance i can i'm just going to take this part off here and then add a

take this part off here and then add a return statement

return statement return and then i can return the name i

return and then i can return the name i can return

can return bo in case that's not the name i can

bo in case that's not the name i can return

return 8 and then i can call this and i'm just

8 and then i can call this and i'm just going to call this with sid

going to call this with sid and we can see what happens

and we can see what happens now

now oh

oh it doesn't it's not it doesn't actually

it doesn't it's not it doesn't actually print what's been returned but if i

print what's been returned but if i print this

print this here we go then we can really see what

here we go then we can really see what happens so

happens so in this function it's going to print

in this function it's going to print this but now we're also going to print

this but now we're also going to print what's returned so let's see what that

what's returned so let's see what that looks like so

looks like so this is what when we print what was

this is what when we print what was returned it looks like this so it's sid

returned it looks like this so it's sid bo

bo 8

8 so one thing related to functions and

so one thing related to functions and also related to other parts of python is

also related to other parts of python is variable scope

variable scope so let's look at this

so let's look at this we've declared a variable up here and

we've declared a variable up here and when you declare a variable that

when you declare a variable that variable is visible in parts of your

variable is visible in parts of your program depending on where you declare

program depending on where you declare it

it so if you declare a variable outside of

so if you declare a variable outside of a function the variable is visible to

a function the variable is visible to any code running after the declare after

any code running after the declare after the declaration including functions so

the declaration including functions so we call this a global variable so we've

we call this a global variable so we've declared this before the function so we

declared this before the function so we can now access it inside a function and

can now access it inside a function and also outside the function so if i

also outside the function so if i so we can see 8 and 8 and it shows right

so we can see 8 and 8 and it shows right here what's going to

here what's going to show in the

show in the console here

console here but if we declare a variable inside a

but if we declare a variable inside a function let me give you an example if

function let me give you an example if we declare

we declare this variable

this variable inside the function i'm just going to

inside the function i'm just going to move it down to here

move it down to here now it's a

now it's a local variable and it's only visible

local variable and it's only visible inside the function so let me just

inside the function so let me just delete with this because it's not

delete with this because it's not actually going to be

actually going to be doing that so if i run this we're going

doing that so if i run this we're going to see there's there's an error

to see there's there's an error name

name age is not defined we're trying to print

age is not defined we're trying to print the age here but since the age was

the age here but since the age was declared inside the function it's not

declared inside the function it's not available outside the function it's only

available outside the function it's only available

available inside the function

inside the function so you just have to be aware sometimes

so you just have to be aware sometimes there's local variables that only apply

there's local variables that only apply inside the function and there's global

inside the function and there's global variables if you that can apply inside a

variables if you that can apply inside a function and outside a function

function and outside a function okay now let's look at something else

okay now let's look at something else with functions and this is nested

with functions and this is nested functions

functions functions in python can be nested

functions in python can be nested inside other functions

inside other functions a function defined inside a function is

a function defined inside a function is visible only inside that function this

visible only inside that function this is useful to create utilities that are

is useful to create utilities that are useful to a function but not useful

useful to a function but not useful outside of it so you might ask why

outside of it so you might ask why should i be hiding this function if it

should i be hiding this function if it does no harm

does no harm well one because it's always best to

well one because it's always best to hide functionality that's local to a

hide functionality that's local to a function if it's not useful elsewhere

function if it's not useful elsewhere also because we can make use of closures

also because we can make use of closures which we'll talk more about later so so

which we'll talk more about later so so look at this example so we have this

look at this example so we have this function talk and inside the function we

function talk and inside the function we defined another function called say

defined another function called say and then

and then what we

what we what we do is that we can call that say

what we do is that we can call that say function

function inside the function and so the way this

inside the function and so the way this works is we pass in the phrase so here's

works is we pass in the phrase so here's the phrase and the phrase i'm going to

the phrase and the phrase i'm going to buy the milk

buy the milk and here we do we we split it so split

and here we do we we split it so split is a way to

is a way to create a list

create a list of out of this string so we have this

of out of this string so we have this string but it's going to split it on

string but it's going to split it on every space so it's going to create a

every space so it's going to create a list of each word individually and then

list of each word individually and then we're going to run this loop

we're going to run this loop more on loops later

more on loops later and we're going to for every word in the

and we're going to for every word in the the words list we're going to say

the words list we're going to say the word we're going to say the word

the word we're going to say the word it's just going to print the word so if

it's just going to print the word so if i just run that i am going to buy the

i just run that i am going to buy the milk and every time it prints it it

milk and every time it prints it it prints it on a new line so this would

prints it on a new line so this would just be an example because we're never

just be an example because we're never going to want to use this save function

going to want to use this save function outside the talk function so it's better

outside the talk function so it's better just to put it inside the talk function

just to put it inside the talk function and then i'll just paste in

and then i'll just paste in another example here if you want to

another example here if you want to access a variable defined in the outer

access a variable defined in the outer function from the inner function

function from the inner function you first need to declare it as

you first need to declare it as non-local

non-local so

so we're using non-local here at non-local

we're using non-local here at non-local count and this allows us to access this

count and this allows us to access this variable that was declared inside the

variable that was declared inside the out so this is the outer function count

out so this is the outer function count and we have this variable called count

and we have this variable called count and to be able to access that variable

and to be able to access that variable in the inner function we have to

in the inner function we have to call non-local or we already talked

call non-local or we already talked about variable scope and if we didn't

about variable scope and if we didn't call

call call this non-local then we could not

call this non-local then we could not access the count variable from inside

access the count variable from inside the function so like for instance i'm

the function so like for instance i'm going to run this it's going to print

going to run this it's going to print the count which is just count plus 1 is

the count which is just count plus 1 is just adding 1 to this number that's all

just adding 1 to this number that's all the function does but if i take off this

the function does but if i take off this word non-local here and i run this we're

word non-local here and i run this we're going to get an error because it doesn't

going to get an error because it doesn't know what count is it doesn't know that

know what count is it doesn't know that we're referring to this count in the

we're referring to this count in the inner function so we'll just put that

inner function so we'll just put that back on there and then it should work

back on there and then it should work again

again this is especially useful with closures

this is especially useful with closures which we're just about to talk about

which we're just about to talk about so closure is a special way of doing a

so closure is a special way of doing a function in python if you return a

function in python if you return a nested function from a function that

nested function from a function that nested function has access to the

nested function has access to the variables defined in that function even

variables defined in that function even if that function is not active anymore

if that function is not active anymore so let me show you an example i'm going

so let me show you an example i'm going to paste some code that'll be very

to paste some code that'll be very similar to this code but just a a little

similar to this code but just a a little different and then i'll explain it so

different and then i'll explain it so now instead of count it's a counter so

now instead of count it's a counter so we're returning count from this nested

we're returning count from this nested function and from the outer function

function and from the outer function we're returning the nested function

we're returning the nested function we're returning the increment function

we're returning the increment function and then here instead of just calling

and then here instead of just calling the function directory the outer

the function directory the outer function we're assigning it to this

function we're assigning it to this variable and now we're going to print

variable and now we're going to print we're just going to call we're going to

we're just going to call we're going to call this variable which is the returned

call this variable which is the returned inner function so we're basically

inner function so we're basically calling the inner function and it's

calling the inner function and it's still going it's because we're calling

still going it's because we're calling the inner function it's not going to

the inner function it's not going to reset the count to zero every time and

reset the count to zero every time and it can keep track of that value and we

it can keep track of that value and we have this

have this using a comment what it's going to

using a comment what it's going to return but we can also

return but we can also run the program and we can see one two

run the program and we can see one two three just like that so we return the

three just like that so we return the increment inner function and that still

increment inner function and that still has access to the state of the count

has access to the state of the count variable even though the counter

variable even though the counter function has ended

function has ended so let's move on to

so let's move on to objects

objects [Music]

[Music] everything in python is an object

everything in python is an object even values of basic prim of types like

even values of basic prim of types like integers strings floats are objects

integers strings floats are objects lists are objects as well as tuples

lists are objects as well as tuples dictionaries and pretty much everything

dictionaries and pretty much everything so objects have attributes and methods

so objects have attributes and methods that can be accessed using the dot

that can be accessed using the dot syntax for example let's define a new

syntax for example let's define a new variable of type int so i'm going to do

variable of type int so i'm going to do age equals eight

age equals eight age now has access to the properties and

age now has access to the properties and methods defined for all int objects

methods defined for all int objects this includes for example access to the

this includes for example access to the real and imaginary part of that number

real and imaginary part of that number so i can do

so i can do a print

a print age dot real

age dot real and then if i just run that

and then if i just run that the real part is eight i can also print

the real part is eight i can also print the imaginary

the imaginary part of the number

part of the number and manage

and manage and there is no imaginary part of the

and there is no imaginary part of the number so it just

number so it just does zero i can also get the the bit

does zero i can also get the the bit length age dot

length age dot bit

bit length

and if i run that we can see the bit length is four so the

we can see the bit length is four so the bit length method returns the number of

bit length method returns the number of bits necessary to represent this number

bits necessary to represent this number in binary notation

in binary notation so there's just a lot of

so there's just a lot of things that you can use for all int

things that you can use for all int objects and these are just a few of them

objects and these are just a few of them so a variable holding a list value has

so a variable holding a list value has access to a different set of methods so

access to a different set of methods so i'm going to

i'm going to update this again we're going to do

update this again we're going to do items

items equals and we're going to create a list

equals and we're going to create a list one

one two

two so

so i can do

i can do items dot

items dot append

append i can append a three i can append

i can append a three i can append another item i can do

another item i can do items dot pop

items dot pop which is going to

which is going to remove and return the last item which is

remove and return the last item which is the three

the three and the methods so so these are the

and the methods so so these are the methods of pin and pop and the methods

methods of pin and pop and the methods available to an object depend on the

available to an object depend on the type of value

type of value the id global function provided by

the id global function provided by python lets you inspect the location in

python lets you inspect the location in memory for a particular object so for

memory for a particular object so for instance i could do a print and i'm

instance i could do a print and i'm going to do id what's the id of the

going to do id what's the id of the items

items object

object and we can see this is the location in

and we can see this is the location in memory

memory so some val some objects are mutable

so some val some objects are mutable while others are immutable this is

while others are immutable this is something that we already talked about a

something that we already talked about a little bit that depends on the object

little bit that depends on the object itself if the object provides methods to

itself if the object provides methods to change its content then it's mutable

change its content then it's mutable otherwise it's immutable

otherwise it's immutable most most types defined by python are

most most types defined by python are immutable for example an int is

immutable for example an int is immutable there are no methods to change

immutable there are no methods to change its value so if you increment the value

its value so if you increment the value like with um

like with um age equals age

age equals age plus

plus one

one it's actually going to create an

it's actually going to create an entirely

entirely new value

new value so it it's not going to even be the same

so it it's not going to even be the same object at all because age you it has to

object at all because age you it has to create a whole new one to reassign it

create a whole new one to reassign it but something like a in in a dictionary

but something like a in in a dictionary it would actually be the same object but

it would actually be the same object but you could just change different parts of

you could just change different parts of it now let's talk more about

it now let's talk more about loops

loops so this song we already discussed a

so this song we already discussed a little bit in the previous section but

little bit in the previous section but loops are

loops are one essential part of programming

one essential part of programming and in python we have two kinds of loops

and in python we have two kinds of loops while loops and for loops

while loops and for loops so before i um show i'm going to paste

so before i um show i'm going to paste in this code but i just want to show

in this code but i just want to show something really quick see how there's a

something really quick see how there's a line like dotted line here and a dotted

line like dotted line here and a dotted line here this is showing the default

line here this is showing the default indentation which we can change so i'm

indentation which we can change so i'm actually going to go and change

actually going to go and change that really quick let me wait i think

that really quick let me wait i think i'm gonna have to yeah i'm gonna zoom

i'm gonna have to yeah i'm gonna zoom out so i can get to this and i'm gonna

out so i can get to this and i'm gonna change the indent to four and now it's

change the indent to four and now it's not going to have a little line right in

not going to have a little line right in there so now i'm going to go back here

there so now i'm going to go back here and let's zoom in again

okay so let's talk about while loops

while loops while loops are defined using the

while loops are defined using the while

while keyword

keyword and they repeat their block until the

and they repeat their block until the the condition is evaluated as false so

the condition is evaluated as false so while condition equals true so

while condition equals true so this particular example is an infinite

this particular example is an infinite loop it never ends because this

loop it never ends because this condition is always going to so if we

condition is always going to so if we run this program which i'm not going to

run this program which i'm not going to do right now because it just goes on

do right now because it just goes on forever while this condition is true

forever while this condition is true keep running the code inside the loop

keep running the code inside the loop all the lines of code that are indented

all the lines of code that are indented the same amount

the same amount so let's halt the loop right after the

so let's halt the loop right after the first iteration i can do condition

first iteration i can do condition equals

equals false

[Music] so now if i run it it just runs the loop

so now if i run it it just runs the loop one time

one time so in this case the first iteration is

so in this case the first iteration is run as the condition is evaluated true

run as the condition is evaluated true and then at the second iteration the

and then at the second iteration the condition test evaluates to false so the

condition test evaluates to false so the control goes to the next instruction

control goes to the next instruction after the loop which in this case there

after the loop which in this case there is no next instruction after the loop

is no next instruction after the loop it's common to have a counter to stop

it's common to have a counter to stop the iteration after some number of

the iteration after some number of cycles

so here's a while loop with a counter so you you start the counter at zero and

you you start the counter at zero and then while count is less than 10.

then while count is less than 10. we're we're gonna print this count

we're we're gonna print this count equals count plus one so it's going to

equals count plus one so it's going to increment the counter every time

increment the counter every time until we get to the end so it's gonna

until we get to the end so it's gonna see it's gonna print this until

see it's gonna print this until eventually the count is

greater than 10 so or 10 or 10 or greater while count is

so or 10 or 10 or greater while count is less than 10. so once it gets to 10 the

less than 10. so once it gets to 10 the loop will stop um again another way to

loop will stop um again another way to doing to do this we could have just done

doing to do this we could have just done plus equals plus equals one so if i run

plus equals plus equals one so if i run that it's going to do the exact same

that it's going to do the exact same thing

thing and other type is the for loop so using

and other type is the for loop so using for loops we can tell python to execute

for loops we can tell python to execute a block for a predetermined amount of

a block for a predetermined amount of times up front and without the need of a

times up front and without the need of a separate variable and conditional to

separate variable and conditional to check its value

check its value it's commonly used to iterate the items

it's commonly used to iterate the items in a list so we have this list there's

in a list so we have this list there's obviously four items here and then four

obviously four items here and then four item in items so items is this list and

item in items so items is this list and then for each item in the list we're

then for each item in the list we're going to print

going to print the item pretty straightforward and it

the item pretty straightforward and it prints each item in the list

prints each item in the list or you can iterate a specific amount of

or you can iterate a specific amount of times using the range function so let's

times using the range function so let's say we don't have we're not going to

say we don't have we're not going to define this here we're just going to do

define this here we're just going to do 4 item in and then here i'm going to

4 item in and then here i'm going to type in range

type in range and then i'm just going to type in a

and then i'm just going to type in a number how about

number how about 15

15 so i'm using the range function that

so i'm using the range function that basically just returns a list and then

basically just returns a list and then if i do that we can see it's going from

if i do that we can see it's going from 0 to 14. so the range function is going

0 to 14. so the range function is going to return a

to return a a list that goes from 0 to 14 so there's

a list that goes from 0 to 14 so there's 15 items and it's going to print the

15 items and it's going to print the items

items now if we just go back a few steps to

now if we just go back a few steps to when we had the list here

when we had the list here we can i can show you how to get the

we can i can show you how to get the index so right now it's just printing

index so right now it's just printing the items one two three four but what if

the items one two three four but what if we want the index of the list

we want the index of the list we can do that by using the by wrapping

we can do that by using the by wrapping the sequence in the enumerate function

the sequence in the enumerate function so for items in and then

so for items in and then i'm going to do

i'm going to do enumerate

so this is going to return each item and

each item and the index of the item and since there's

the index of the item and since there's going to be an item in an index

going to be an item in an index but it's actually the index and then the

but it's actually the index and then the item i'm going to type an index comma

item i'm going to type an index comma item so this enumerate is going to get

item so this enumerate is going to get the index and the item so now i can

the index and the item so now i can print the index and the item here and if

print the index and the item here and if i run that

i run that so index zero item one index one item

so index zero item one index one item two index two item three and so on and

two index two item three and so on and it doesn't even have to be numbers we

it doesn't even have to be numbers we can

do names [Music]

and if i just run that whoops not that one

one and then we can see the the index and

and then we can see the the index and the item then let me put in some more

the item then let me put in some more code here so i can talk about break and

code here so i can talk about break and continue

continue both while and for loops can be

both while and for loops can be interrupted inside the block using

interrupted inside the block using either break or continue

either break or continue continue stops the current iteration and

continue stops the current iteration and tells python to execute the next one

tells python to execute the next one and break stops the loop altogether and

and break stops the loop altogether and goes on with the next instruction after

goes on with the next instruction after the loop ends so i'm going to just play

the loop ends so i'm going to just play this so here we're saying if item equals

this so here we're saying if item equals two continues that means it's going to

two continues that means it's going to skip that iteration so if i play this

skip that iteration so if i play this one three four so it's not going to it's

one three four so it's not going to it's not going to get to the print item

not going to get to the print item because it's actually skipped that

because it's actually skipped that iteration it just

iteration it just doesn't run any code after the continue

doesn't run any code after the continue if this is true

if this is true and so it doesn't print 2. so if we

and so it doesn't print 2. so if we change this to break it will be very

change this to break it will be very it'll be a little different here this

it'll be a little different here this time it's going to just print one

time it's going to just print one because now it's breaking out of the

because now it's breaking out of the loop

loop entirely and it's not going to run any

entirely and it's not going to run any more iteration of the loop

more iteration of the loop okay let's talk about another thing

okay let's talk about another thing classes classes in python

classes classes in python so in addition to using the python

so in addition to using the python provided types we can declare our own

provided types we can declare our own classes

classes and from the classes we can instantiate

and from the classes we can instantiate objects

objects an object is an instance of a class

an object is an instance of a class a class is the type of an object so

a class is the type of an object so here's an example i'm going to create a

here's an example i'm going to create a class called

class called dog

dog so

so uh to create a class you just put the

uh to create a class you just put the word class and then put the the class

word class and then put the the class name

name and

and now

now i can i can

i can i can add a method for the class so to define

add a method for the class so to define a method i'll just do define bark

a method i'll just do define bark [Music]

[Music] and i'm going to put the word self here

and i'm going to put the word self here and inside this i'll print

[Music] woof

woof [Music]

okay so self as an argument of the method

method will point to the current object

will point to the current object instance and must be specified when

instance and must be specified when defining a method so when you're

defining a method so when you're creating a method inside a class you're

creating a method inside a class you're always going to start with self so we

always going to start with self so we create an instance of a class

create an instance of a class which is an object

which is an object like this

like this so i'm just going to put

so i'm just going to put roger

roger equals

equals dog

dog okay so i've created a dog just like

okay so i've created a dog just like this

this and then i can

and then i can print

print type

type roger so let's see what the type of this

roger so let's see what the type of this roger is we can see it's the class to

roger is we can see it's the class to dog class

dog class roger is a dog

roger is a dog a special type of method

a special type of method called in there's a special type of

called in there's a special type of method called init which is a

method called init which is a constructor

constructor so let me show you how to create a

so let me show you how to create a constructor

constructor deaf

so we can use this a constructor like this

a constructor like this to initialize one more properties when

to initialize one more properties when we create a new object from that class

we create a new object from that class so you can see we always have to add

so you can see we always have to add self but now these are the two

self but now these are the two variables we can pass in when we create

variables we can pass in when we create a dog and that will associate be

a dog and that will associate be associated with that

associated with that that

that object

object so down here i can call um i can call

so down here i can call um i can call dog but i can pass in roger for the name

dog but i can pass in roger for the name and

and the age

the age and now when we create this

and now when we create this dog it's going to assign the name to

dog it's going to assign the name to self.name and it's going to assign the

self.name and it's going to assign the age to self.age and let me show you how

age to self.age and let me show you how you can access that information

you can access that information so i'm going to print instead of

so i'm going to print instead of printing the type i'm going to do roger

printing the type i'm going to do roger dot name

dot name and now it's going to when i do

and now it's going to when i do roger.name that's self.name so self is

roger.name that's self.name so self is roger and we do self.name it's going to

roger and we do self.name it's going to be the name that was passed in

be the name that was passed in and then we can also

and then we can also do the age

do the age and then we can finally

and then we can finally call the bark method so we have bark

call the bark method so we have bark here now we can see what that does so

here now we can see what that does so i'm just going to run that

i'm just going to run that and we have roger

and we have roger we have eight

we have eight and then

and then this is because i should have put

this is because i should have put parentheses here so let me put

parentheses here so let me put parentheses after bark

parentheses after bark and so we have wolf here so roger 8

and so we have wolf here so roger 8 wolf and the reason why it says none

wolf and the reason why it says none here is because i didn't have to put the

here is because i didn't have to put the print see i i put pranks that was in

print see i i put pranks that was in this groove if you're playing print on

this groove if you're playing print on everything but calling bark

everything but calling bark already prints wolf

already prints wolf so when i do

so when i do it when it's when it's printing it's

it when it's when it's printing it's printing because since

printing because since roger.bark doesn't return anything

roger.bark doesn't return anything there's no return statement that's why

there's no return statement that's why it printed none so there'd be two ways

it printed none so there'd be two ways to fix that either instead of printing

to fix that either instead of printing wolf i could return wolf

wolf i could return wolf or i could just not do the print here so

or i could just not do the print here so let me just take that off

let me just take that off okay roger 8

okay roger 8 wolf

wolf so one important feature of class is

so one important feature of class is inheritance let me show you an example

inheritance let me show you an example of inheritance i'm going to create a new

of inheritance i'm going to create a new class before the dog class and this is

class before the dog class and this is going to be

going to be a class

a class called

called animal

animal and the animal class i'm going to put a

and the animal class i'm going to put a function called walk

function called walk and i'm going to always pass in self

and i'm going to always pass in self and this is going to print

and this is going to print [Music]

[Music] walking

walking [Music]

[Music] and then we can make the dog class

and then we can make the dog class inherent inherit from the animal class

inherent inherit from the animal class so we have class dog but if i put

so we have class dog but if i put parentheses here

parentheses here then i can type in animal

then i can type in animal and now the dog class is going to

and now the dog class is going to inherit from the animal class and now i

inherit from the animal class and now i can go down here and after roger.bark i

can go down here and after roger.bark i can do roger.walk

can do roger.walk and if i run that

and if i run that okay so roger 8wolf but now it's going

okay so roger 8wolf but now it's going to be able to do walking and you can see

to be able to do walking and you can see the dog class doesn't actually have a

the dog class doesn't actually have a walk method but it's getting it from

walk method but it's getting it from the animal class it's inheriting this

the animal class it's inheriting this method

method and in that way you're able to i could

and in that way you're able to i could create a class cat a class frog

create a class cat a class frog a class bird and each of them could

a class bird and each of them could inherit the walk

inherit the walk method and then it would have

method and then it would have walking

walking and we'll be doing a little more with

and we'll be doing a little more with classes in the the final project

classes in the the final project in this course

in this course because we'll be going a little more

because we'll be going a little more over object oriented programming

over object oriented programming but right now let's talk about something

but right now let's talk about something new i'm going to just delete all this

new i'm going to just delete all this and we're going to be talking about

and we're going to be talking about modules

modules so every python file is a module you can

so every python file is a module you can import a module from other files and

import a module from other files and that's the base of any program of

that's the base of any program of moderate complexity as it promotes a

moderate complexity as it promotes a sensible organization and code reuse so

sensible organization and code reuse so it's basically how you can create a

it's basically how you can create a software that has multiple python

software that has multiple python programs in the same piece of software

programs in the same piece of software so in the typical python program one

so in the typical python program one file acts as the entry point and the

file acts as the entry point and the other files are modules and exposed

other files are modules and exposed functions that we can call from

functions that we can call from other files so

other files so let me just show you an example i am

let me just show you an example i am going to

going to open up this

open up this files tab and i'm going to create a new

files tab and i'm going to create a new file and this is going to be called dog

file and this is going to be called dog dot pi

dot pi and now i have dog dot pi open i no

and now i have dog dot pi open i no longer have the main dot pi open and i'm

longer have the main dot pi open and i'm going to define

going to define bark

bark and what bark is going to do is just

and what bark is going to do is just print

print woof

woof [Music]

[Music] okay now i'm going to it's just going to

okay now i'm going to it's just going to automatically save for me i'm going to

automatically save for me i'm going to go back to the the python file and now

go back to the the python file and now i'm going to

i'm going to import

import dog

dog and let's see oh it's just saying it's

and let's see oh it's just saying it's unused i thought maybe this thing wrong

unused i thought maybe this thing wrong but that just means i import dog and i

but that just means i import dog and i haven't used it which i'm about to do

haven't used it which i'm about to do right now so dog

right now so dog dot

dot bark

bark so now if i run this program

so now if i run this program it's going to say wolf but that's not

it's going to say wolf but that's not from this file it's actually importing

from this file it's actually importing this function from from the dog file so

this function from from the dog file so that's a way you can

that's a way you can break up your code into multiple files

break up your code into multiple files we can also use the from import syntax

we can also use the from import syntax and call the function directly

and call the function directly let me show you what i mean so instead

let me show you what i mean so instead of import dog i'm going to say

of import dog i'm going to say from dog

from dog import

import bark

bark and then instead of calling it dog.bark

and then instead of calling it dog.bark i can just call

i can just call bark

bark because we're only importing bark well

because we're only importing bark well we've imported bark directly instead of

we've imported bark directly instead of the whole dog so i can run that and it

the whole dog so i can run that and it says

says wolf

wolf so

so the first strategy allows us to load

the first strategy allows us to load everything defined in a file when i just

everything defined in a file when i just said

said import dog that

import dog that allows everything defined in a file so i

allows everything defined in a file so i could have a bunch of function like bark

could have a bunch of function like bark or walk

or walk name or there could be a bunch of

name or there could be a bunch of functions if i just say import dog it

functions if i just say import dog it imports all of them but the second

imports all of them but the second strategy from dog import bark allows us

strategy from dog import bark allows us to just pick the things we need so we're

to just pick the things we need so we're only going to import the specific

only going to import the specific functions that we need

functions that we need those modules are specific to your

those modules are specific to your program and importing depends on the

program and importing depends on the location of the file in the file system

location of the file in the file system so

so suppose you put dog.pi in a

suppose you put dog.pi in a subfolder for instance let's say i

subfolder for instance let's say i create a folder

create a folder and i call it liv for library and let's

and i call it liv for library and let's say i put dog.pi in this subfolder like

say i put dog.pi in this subfolder like this

this now in this folder to make this work i'm

now in this folder to make this work i'm going to have to create an empty file

going to have to create an empty file named init.pie so i'm going to add file

named init.pie so i'm going to add file and i'll do init dot or under underscore

and i'll do init dot or under underscore underscore init underscore underscore

underscore init underscore underscore dot pi

dot pi and this tells python that

and this tells python that the folder contains modules

the folder contains modules now i'm going to go back to my main file

now i'm going to go back to my main file and i can

and i can i can import dog from

i can import dog from lib so i'm going to say from

lib so i'm going to say from lib

lib that's that subfolder import

that's that subfolder import dog

dog and then i can do

and then i can do dog

dog dot bark so let's run that to make sure

dot bark so let's run that to make sure there's no errors it worked

there's no errors it worked correctly so i was able to import this

correctly so i was able to import this file from the subfolder

file from the subfolder or you can reference the dog module

or you can reference the dog module specific function by importing from

specific function by importing from lib.dog so i can do from

lib.dog so i can do from lib.dog

lib.dog import

import bark and now instead of calling dog.bark

bark and now instead of calling dog.bark i can just call

i can just call bark

bark and it says

and it says wolf

wolf so i'm going to close this here

so i'm going to close this here and

and now let's talk about the python standard

now let's talk about the python standard library so basically there's all these

library so basically there's all these pre-built modules you can

pre-built modules you can you can load a lot of code from the

you can load a lot of code from the standard library python exposes a lot of

standard library python exposes a lot of built-in functionality through its

built-in functionality through its standard library

standard library the stand library is a huge collection

the stand library is a huge collection of all sorts of utilities ranging from

of all sorts of utilities ranging from math utilities to debugging to creating

math utilities to debugging to creating graphical user interfaces

graphical user interfaces so there's a bunch of them but here's

so there's a bunch of them but here's some of the more common ones we have

some of the more common ones we have math for math utilities re regular

math for math utilities re regular expressions json to work with json date

expressions json to work with json date time sqlite 3 os for operating system

time sqlite 3 os for operating system utilities random for random number

utilities random for random number generations

generations so

so statistics requests for http request

statistics requests for http request http to create servers url lib to manage

http to create servers url lib to manage urls so you can import these modules

urls so you can import these modules that allow you to get extra

that allow you to get extra functionality so

functionality so we already looked at a little bit at the

we already looked at a little bit at the math one we already looked a little bit

math one we already looked a little bit at random in the the first

at random in the the first uh project that we did but let's just

uh project that we did but let's just kind of look at a little more how you

kind of look at a little more how you would do this so now we are going to use

would do this so now we are going to use the the math one we're going to import

the the math one we're going to import math

math and

and so this is how you would introduce you

so this is how you would introduce you would use a module of the standard

would use a module of the standard library so we already saw how to import

library so we already saw how to import modules that we created it's very stan

modules that we created it's very stan it's very similar with the standard

it's very similar with the standard library so now that i've imported math i

library so now that i've imported math i can now use

can now use functions and methods from from the math

functions and methods from from the math module so i can do math dot

module so i can do math dot square root and i can pass in 4 and then

square root and i can pass in 4 and then i can just

i can just print that so we can see what the result

print that so we can see what the result is

okay 2.0 or we can

or we can just like we shall

just like we shall we saw before instead of importing math

we saw before instead of importing math i can say

i can say from math

from math import

import square root and then instead of just

square root and then instead of just doing math dot square root i can just

doing math dot square root i can just call

call this

this square root method here and it's going

square root method here and it's going to do the same thing so that's basically

to do the same thing so that's basically how it works for for all the modules in

how it works for for all the modules in the standard library okay now we're

the standard library okay now we're going to start going over a few kind of

going to start going over a few kind of miscellaneous

miscellaneous slightly more advanced topics in python

slightly more advanced topics in python so we're going to talk about how to

so we're going to talk about how to accept arguments from the command line

accept arguments from the command line in python

in python well first of all let's see how to run a

well first of all let's see how to run a program from the command line

program from the command line in replit so let's say we have a program

in replit so let's say we have a program it just says print

it just says print hello okay so we've been running it by

hello okay so we've been running it by just clicking this play button but

just clicking this play button but there's another way to run a program in

there's another way to run a program in replit and i go over to the shell so

replit and i go over to the shell so this is the command line in replica we

this is the command line in replica we can clear this

can clear this and now i'm just going to type in

and now i'm just going to type in python main dot pi

python main dot pi okay so what we call python to run the

okay so what we call python to run the python program and then we just put the

python program and then we just put the name of our file with main.pi

name of our file with main.pi so

so whether you're in replit or if you're

whether you're in replit or if you're running things locally

running things locally you should be able to

you should be able to run a program in the same way

run a program in the same way depending on how you install the program

depending on how you install the program locally instead of typing python you may

locally instead of typing python you may type in python 3.

type in python 3. sometimes the way people install python

sometimes the way people install python it will be python 3 because we're using

it will be python 3 because we're using version 3 of python

version 3 of python so now let's see how you can

so now let's see how you can call a python a program on the command

call a python a program on the command line and pass in some arguments right

line and pass in some arguments right when we run the program from the command

when we run the program from the command line

line so

so a basic way to handle arguments is to

a basic way to handle arguments is to use the sys module from the standard

use the sys module from the standard library so let me give you an example so

library so let me give you an example so first of all we're going to import sys

first of all we're going to import sys now just so you know usually you're

now just so you know usually you're always going to have import statements

always going to have import statements on the first line i'm just putting this

on the first line i'm just putting this comment on the first line to remind us

comment on the first line to remind us what we're working on right now so now

what we're working on right now so now i'm going to we're going to import the

i'm going to we're going to import the sys library

sys library now i'm going to

now i'm going to print

print and i'm going to first i'm going to

and i'm going to first i'm going to oh

oh we're going to print the argument

we're going to print the argument cis.arg

cis.arg the

the so this is how we can print all the

so this is how we can print all the arguments that were passed in

arguments that were passed in when we called the program so so i'm

when we called the program so so i'm going to see we have python main.pi and

going to see we have python main.pi and now i'm going to put

now i'm going to put bow

bow 39

39 okay so you can see it's printing the

okay so you can see it's printing the list of arguments so this is basically

list of arguments so this is basically just a list the first item is the name

just a list the first item is the name of file

of file then we have

then we have the the first word and then the second

the the first word and then the second one and you can see they're both strings

one and you can see they're both strings even though this is a number it's coming

even though this is a number it's coming in

in as a string so then we could do

as a string so then we could do something like this we could say name

something like this we could say name equals cis.arg v

equals cis.arg v and then i would

and then i would get the element at index 1 which is the

get the element at index 1 which is the name here and i could print

[Music] hello

hello and then we're going to do a name oh

and then we're going to do a name oh hello hello and then name so let's call

hello hello and then name so let's call this again

this again and instead of i'm not going to do 39

and instead of i'm not going to do 39 it's just going to be python main.pi bow

it's just going to be python main.pi bow hello bo so we've now been able to use

hello bo so we've now been able to use the argument that was passed in

the argument that was passed in now this is a simple way to do it but

now this is a simple way to do it but you

you really would have to do a lot of work

really would have to do a lot of work using this method because you really

using this method because you really should validate the arguments make sure

should validate the arguments make sure the type is correct and you need to

the type is correct and you need to print feedback to the user if they're

print feedback to the user if they're not using the program correctly

not using the program correctly so i got zoomed out a little bit and i'm

so i got zoomed out a little bit and i'm going to show you this other method

going to show you this other method so python provides another package in

so python provides another package in the standard library to help you called

the standard library to help you called arg parse so first you would insert

arg parse so first you would insert import arg parse

import arg parse [Music]

[Music] and then let me show you

and then let me show you how you would use it

how you would use it so you call arc parse dot argument

so you call arc parse dot argument parser

parser and then pass in the description of the

and then pass in the description of the program so the description of the

program so the description of the program is this program prints the name

program is this program prints the name of my dogs

of my dogs then

then you proceed to add arguments you want to

you proceed to add arguments you want to accept

accept so for this example program we are going

so for this example program we are going to accept the c option or it can be

to accept the c option or it can be slash

slash c or dash that's color

c or dash that's color and we are going to

and we are going to be calling it color and then later we

be calling it color and then later we can we do

can we do parser.parse args

parser.parse args and then we can access args

and then we can access args dot color to get the color that was

dot color to get the color that was passed in and then you can specify

passed in and then you can specify whether it's required and what help is

whether it's required and what help is going to go along with that so let me

going to go along with that so let me show you how you would do that

show you how you would do that we're going to do python

we're going to do python main dot pi i'm going to put dash c and

main dot pi i'm going to put dash c and then i'm just going to put red

then i'm just going to put red okay so

okay so you can see if i

you can see if i go this out a little more you can see

go this out a little more you can see this is the

this is the command i called this is the command i

command i called this is the command i run i pass in red and then it just

run i pass in red and then it just printed red that's what we have right

printed red that's what we have right here

here and so let me show you what would happen

and so let me show you what would happen if we if we

if we if we don't specify the argument so if i just

don't specify the argument so if i just run it without the red so it's now

run it without the red so it's now giving me

giving me some information usage well main.pi we

some information usage well main.pi we need to put dash c and then we have to

need to put dash c and then we have to put a color and then it says the

put a color and then it says the following

following arguments are required this dashi or

arguments are required this dashi or dash sc so it's it's showing us that we

dash sc so it's it's showing us that we need to

need to if we we've called the program wrong and

if we we've called the program wrong and we're going to need to call it with the

we're going to need to call it with the dash c

dash c you can also

you can also set this option

set this option we can set an option to have a specific

we can set an option to have a specific set of values using choices so after

set of values using choices so after required true after this comma i'm going

required true after this comma i'm going to type in choices and i'm going to set

to type in choices and i'm going to set this to equal

see i have this empty dictionary

dictionary but i'm just going to well not a

but i'm just going to well not a dictionary but

dictionary but because it's not going to key value

because it's not going to key value pairs i can do red

pairs i can do red and yellow

and yellow so now it's it can only accept

so now it's it can only accept two options so i can

two options so i can call it here

call it here with

with red

red but if i call with blue

but if i call with blue it will say

it will say invalid choice blue i need to choose

invalid choice blue i need to choose from red or yellow so

from red or yellow so using this arc parse makes it easier to

using this arc parse makes it easier to deal with arguments and also makes it

deal with arguments and also makes it easier to

easier to communicate information back to the user

communicate information back to the user about what we're trying to get

about what we're trying to get so there are more options with this but

so there are more options with this but those are those are the basics

those are those are the basics now let's talk about something

now let's talk about something completely different

completely different lambda

lambda lambda

lambda functions

functions so let me just give you a quick example

so let me just give you a quick example [Music]

lambda num num

num [Music]

[Music] times

times 2. so

2. so lambda functions

lambda functions also called anonymous functions are tiny

also called anonymous functions are tiny functions they have no name and only

functions they have no name and only have one expression as their body

have one expression as their body so they're defined using the lambda

so they're defined using the lambda keyword and so

keyword and so this is going to be the argument

this is going to be the argument and this is going to be the expression

and this is going to be the expression the body must be a single expression and

the body must be a single expression and it has to be an expression not a

it has to be an expression not a statement so this difference is

statement so this difference is important an expression returns a value

important an expression returns a value a statement does not so it has to return

a statement does not so it has to return a value so the value that's being

a value so the value that's being returned is the number times two the

returned is the number times two the number that was passed in going to

number that was passed in going to multiply it by 2 in this example

multiply it by 2 in this example so this is basically the simplest

so this is basically the simplest example of a lambda function it just

example of a lambda function it just doubles the value of a number and lambda

doubles the value of a number and lambda functions can accept more

functions can accept more arguments so

arguments so so for instance i could do

so for instance i could do [Music]

[Music] lambda

lambda a comma b

a comma b and then we can multiply a times b

and then we can multiply a times b lambda functions cannot be invoked

lambda functions cannot be invoked directly but you can't assign them to

directly but you can't assign them to variables so for instance i can assign

variables so for instance i can assign this to the variable called

this to the variable called multiply so multiply is going to this

multiply so multiply is going to this function is going to be assigned to this

function is going to be assigned to this variable here so then the way that i

variable here so then the way that i would use that i could print now i'll

would use that i could print now i'll print the result of calling multiply

print the result of calling multiply and then i pass in

and then i pass in two

two and four

and four so if i just run that okay 2 times 4 is

so if i just run that okay 2 times 4 is 8. we can see right in the console here

8. we can see right in the console here and then i'm going to just

and then i'm going to just zoom in just a little bit

zoom in just a little bit so the utility of lambda functions comes

so the utility of lambda functions comes when combined with other python

when combined with other python functionality for example in combination

functionality for example in combination with map filter and reduce so speaking

with map filter and reduce so speaking of map filter and reduce that's what

of map filter and reduce that's what we're going to talk about now map

we're going to talk about now map filter

filter reduce

reduce so python provides three useful global

so python provides three useful global functions we that we can use to work

functions we that we can use to work with collections so this is map filter

with collections so this is map filter reduce so first let's talk about

reduce so first let's talk about map and since their functions are going

map and since their functions are going to have the

to have the parentheses at the end so map is used to

parentheses at the end so map is used to run a function

run a function upon each item in an iterable item like

upon each item in an iterable item like a list and create a new list with the

a list and create a new list with the same number of items but the values of

same number of items but the values of each item can be changed so here's an

each item can be changed so here's an example we have this list

example we have this list and then here's the function

and then here's the function and then we are going to map through

and then we are going to map through each item in the list

each item in the list and so here's the function we're going

and so here's the function we're going to run we're going to run this function

to run we're going to run this function on each item in the list

on each item in the list and now we're going to get a new list so

and now we're going to get a new list so i can do print

i can do print result now if we print that i'll just

result now if we print that i'll just run that function and we can see

run that function and we can see okay we get a map object

so then we can always just pass it into the

the list function

list function and then we can

and then we can run the program again two four six so

run the program again two four six so one two three became two four

one two three became two four so yeah whenever you want to do run a

so yeah whenever you want to do run a function on each item in a list you can

function on each item in a list you can use map

use map and when the function is a one-liner

and when the function is a one-liner it's common to use a lambda function so

it's common to use a lambda function so we just talked about lambda functions so

we just talked about lambda functions so now let me show you how you would do

now let me show you how you would do this as a lambda function so

this as a lambda function so double

double is going this is going to be a variable

is going this is going to be a variable and we're going to assign it to a lambda

and we're going to assign it to a lambda function

function and i'm going to

so now this lambda function takes the number

number a

a and then does a times two so and this we

and then does a times two so and this we just keep the same because now we're

just keep the same because now we're using a lambda function here and we're

using a lambda function here and we're taking each number and passing it

taking each number and passing it through this function where we have the

through this function where we have the the this is each number in the list and

the this is each number in the list and we multiply it so if i run this program

we multiply it so if i run this program it should look exactly the same

it should look exactly the same and we can even simplify it even more so

and we can even simplify it even more so this is where lambda functions really

this is where lambda functions really shine instead of assign it assigning it

shine instead of assign it assigning it to double first i can copy the whole

to double first i can copy the whole function i can delete this completely

function i can delete this completely and now i can just put it right in here

and now i can just put it right in here so now we're mapping over this function

so now we're mapping over this function and we don't even have to create the

and we don't even have to create the function in a different line and assign

function in a different line and assign it to a variable first we can put the

it to a variable first we can put the lambda function right in the same line

lambda function right in the same line right within the map and now i run this

right within the map and now i run this and it's going to give us the same

and it's going to give us the same result so remember we started with

result so remember we started with when i first showed you this example we

when i first showed you this example we had a much longer piece of code now

had a much longer piece of code now we've simplified it with the

we've simplified it with the lambda function

lambda function so the original list the original list

so the original list the original list is left untouched in a new list with the

is left untouched in a new list with the updated values is returned by map

updated values is returned by map the result is a map object which is an

the result is a map object which is an iterable so

iterable so that's why we needed to cast it to list

that's why we needed to cast it to list to print its content

to print its content okay now let's talk about filter

okay now let's talk about filter let me put in let me just update the

let me put in let me just update the code here it's kind of similar but now

code here it's kind of similar but now we're using filter filter takes an

we're using filter filter takes an iterable and returns a filter object

iterable and returns a filter object which is another iterable but without

which is another iterable but without some of the original items so you can do

some of the original items so you can do so by returning true or false from the

so by returning true or false from the filtering

filtering the filtering function so here's the

the filtering function so here's the filtering function we are going to check

filtering function we are going to check if the item passed in is even so

if the item passed in is even so so here's the list here so

so here's the list here so you can see we're calling filter we pass

you can see we're calling filter we pass in the function the filtering function

in the function the filtering function and then the list

and then the list and we're going to return true or false

and we're going to return true or false from this function so if it can be if

from this function so if it can be if it's divisible by if when you divide it

it's divisible by if when you divide it by two we have zero remainder

by two we have zero remainder then it's even

then it's even so

so that would return true so this line

that would return true so this line would return true

would return true and then if not it would return false if

and then if not it would return false if it's odd so now any even number is going

it's odd so now any even number is going to be added to the result and any odd

to be added to the result and any odd number is not going to be added to the

number is not going to be added to the result so basically we're filtering the

result so basically we're filtering the list based on this function and then

list based on this function and then here we just print

here we just print we convert that result to a list and if

we convert that result to a list and if we run that it's two and obviously if we

we run that it's two and obviously if we can just put in

can just put in uh more numbers here

uh more numbers here and run that again

and run that again we have two four six

we have two four six and then we can just like before we can

and then we can just like before we can use a lambda function so

use a lambda function so i'm just going to

i'm just going to copy this here we can just delete this

copy this here we can just delete this whole thing and we are going to put a

whole thing and we are going to put a lambda function here so lamb

lambda function here so lamb duh

duh [Music]

[Music] so now you can see we're just putting

so now you can see we're just putting the lambda function in the in line here

the lambda function in the in line here and we are checking to see if it's this

and we are checking to see if it's this is going to turn true or false whether

is going to turn true or false whether it's even or not

it's even or not and so i run the program and it's going

and so i run the program and it's going to give me the exact same result here

to give me the exact same result here okay the final thing we're going to talk

okay the final thing we're going to talk about is reduce

about is reduce reduce is used to calculate a value out

reduce is used to calculate a value out of a sequence like a list so for example

of a sequence like a list so for example suppose we have this list of expenses

suppose we have this list of expenses stored as tuples

stored as tuples and so so we had dinner 80 car repair

and so so we had dinner 80 car repair 180 or 120 and we want to calculate the

180 or 120 and we want to calculate the sum

sum of this property

of this property in each tuple

in each tuple in this case the cost of the expense

in this case the cost of the expense so here's kind of the long way of doing

so here's kind of the long way of doing it without using reduce

it without using reduce we basically take every expense in

we basically take every expense in expenses and then we add to the sum here

expenses and then we add to the sum here and we add expense one that's going to

and we add expense one that's going to be the

be the the item at index one and then we get

the item at index one and then we get the sum and we can print the sum so

the sum and we can print the sum so that's kind of like the long way of

that's kind of like the long way of doing it without reduce but there's a

doing it without reduce but there's a quicker way so

quicker way so to use reduce reduce is a little

to use reduce reduce is a little different from map and filter where it's

different from map and filter where it's not available it's not it's not

not available it's not it's not available automatically we have to

available automatically we have to import it from the standard library func

import it from the standard library func tools so i'll do from

tools so i'll do from funk

funk tools or function tools

tools or function tools import

import [Music]

[Music] reduce

create a new i'm going to create a new variable called sum

variable called sum and we're going to set it to

and we're going to set it to reduce we're going to use reduce and now

reduce we're going to use reduce and now i'm just going to

i'm just going to pass in i'm going to go directly to the

pass in i'm going to go directly to the lambda function so

lambda function so lambda

let me just kind of explain this for a little bit so reduce the first is going

little bit so reduce the first is going to take a function the reduction

to take a function the reduction function

function and then

and then the iterable here

the iterable here and the function has to take two

and the function has to take two arguments

arguments so this the first argument is the

so this the first argument is the accumulated value and then the the right

accumulated value and then the the right argument is

argument is the updated the update value from the

the updated the update value from the iterable so we're going to

iterable so we're going to continue adding

continue adding these two item we're going to

these two item we're going to basically add every item together and

basically add every item together and reduce

reduce the

the i the numbers at the first index all

i the numbers at the first index all into down to one value by adding them

into down to one value by adding them all together so i'll just

all together so i'll just pray here play here and then we get the

pray here play here and then we get the same number 200 and you can see it's a

same number 200 and you can see it's a lot it's a lot quicker just to use the

lot it's a lot quicker just to use the reduce function compared to the other

reduce function compared to the other code we had previously

code we had previously okay next up we are going to talk about

okay next up we are going to talk about recursion

recursion in

in python not recursion error just

python not recursion error just recursion

recursion and a function in python can call itself

and a function in python can call itself that's what recursion is and it can be

that's what recursion is and it can be pretty useful in many scenarios a common

pretty useful in many scenarios a common way to explain recursion is by using the

way to explain recursion is by using the factorial calculation

factorial calculation so let me show you how you would

so let me show you how you would calculate factorial this isn't python

calculate factorial this isn't python code this is just an example here so a

code this is just an example here so a fact when you do 3 factorial that means

fact when you do 3 factorial that means you do 3

you do 3 you multiply every number between three

you multiply every number between three between this number and one together so

between this number and one together so three times two times one equals six

three times two times one equals six four factorial is four times three times

four factorial is four times three times two times one five factorial is you know

two times one five factorial is you know five through one and so on and then

five through one and so on and then every number you multiply every whole

every number you multiply every whole number down to one so using recursion we

number down to one so using recursion we can write a function that calculates the

can write a function that calculates the factorial of any number so let me show

factorial of any number so let me show you so here's the function you can see

you so here's the function you can see inside the function it's calling the

inside the function it's calling the same function so a recursive function

same function so a recursive function it's always going to have a base case

it's always going to have a base case that's this

that's this and the recursive case so the base case

and the recursive case so the base case is when we're going to leave the

is when we're going to leave the the recursive function so if n is equal

the recursive function so if n is equal to one we're going to return one and

to one we're going to return one and that's basically going to get out of the

that's basically going to get out of the recursive function uh but if n is not

recursive function uh but if n is not going to equal one then we have the

going to equal one then we have the recursive the recursive case where we're

recursive the recursive case where we're going to call the function so you always

going to call the function so you always need to have at least you always have

need to have at least you always have need to have a base case so eventually

need to have a base case so eventually the recursion can stop

the recursion can stop if the recursion doesn't ever stop

if the recursion doesn't ever stop then you're going to get a recursion

then you're going to get a recursion error

error basically python by default will halt

basically python by default will halt recursions at 1000 calls and that's when

recursions at 1000 calls and that's when you get the recursion error so this is

you get the recursion error so this is going to get the factorial three but

going to get the factorial three but let's just do this a few more times so

let's just do this a few more times so you can see the difference so three

you can see the difference so three four

four five and now we'll test this out

five and now we'll test this out 6 24

6 24 120.

120. okay now let's talk about decorators

okay now let's talk about decorators so decorators in python are a way to

so decorators in python are a way to change enhance or alter in any way how a

change enhance or alter in any way how a function works decorators are defined

function works decorators are defined with the at symbol followed by the

with the at symbol followed by the decorator name just before the function

decorator name just before the function definition

definition so for instance let's say we have a

so for instance let's say we have a function

function hello

hello and it's just going to be the simplest

and it's just going to be the simplest function we're just going to print

hello uh so

uh so to make that to add a decorator i'm

to make that to add a decorator i'm going to put like this an at sign and

going to put like this an at sign and then the decorator name in this

then the decorator name in this case we're going to type in log time so

case we're going to type in log time so the function has the log time decorator

the function has the log time decorator assigned so

assigned so whenever we call the hello function the

whenever we call the hello function the decorator is going to be called a

decorator is going to be called a decorator is a function that takes a

decorator is a function that takes a function as a parameter wraps the

function as a parameter wraps the function in an inner function that

function in an inner function that performs the job it has to do and

performs the job it has to do and returns that inner function

returns that inner function so for instance i'm going to create

so for instance i'm going to create another function here that's going to be

another function here that's going to be the log time function

the log time function and now we we can do something before

and now we we can do something before and after the function like for instance

and after the function like for instance we can say

we can say print

before and then after

and then after we are going to print

we are going to print after

after now if i run this

oh and we have to call the function that's always important

that's always important now if i run this

now if i run this before hello after

before hello after so you're going to often use decorator

so you're going to often use decorator functions when you want to change the

functions when you want to change the behavior of a function without modifying

behavior of a function without modifying the function itself so a few good

the function itself so a few good examples are when you want to add

examples are when you want to add logging test performance perform caching

logging test performance perform caching verify permissions and so on

verify permissions and so on you can also use one when you need to

you can also use one when you need to run the same code on multiple functions

run the same code on multiple functions okay now let's talk about doc strings so

okay now let's talk about doc strings so doc strings

doc strings [Music]

[Music] documentation is hugely important not

documentation is hugely important not just to communicate to other people what

just to communicate to other people what the goal of a function or class or

the goal of a function or class or method or module is but it's also it

method or module is but it's also it also communicates to yourself when you

also communicates to yourself when you come back to your code like many months

come back to your code like many months from now you might not remember all the

from now you might not remember all the knowledge you were holding in your head

knowledge you were holding in your head when you wrote the code so at that point

when you wrote the code so at that point reading your code and understanding what

reading your code and understanding what it's supposed to do

it's supposed to do so that at that point reading your code

so that at that point reading your code and understanding what it's supposed to

and understanding what it's supposed to do will be a lot more difficult so a lot

do will be a lot more difficult so a lot that's one of the reasons why people add

that's one of the reasons why people add comments so another way is to use a doc

comments so another way is to use a doc string so let me show you what a doc

string so let me show you what a doc string looks like

string looks like the utility of a doc strings is that

the utility of a doc strings is that they follow conventions

they follow conventions so they can be processed automatically

so they can be processed automatically so this is how you would define a doc

so this is how you would define a doc string for a function

string for a function basically you're putting the three

basically you're putting the three quotation marks here three quotation

quotation marks here three quotation marks there and then this is a

marks there and then this is a description of what the function is

description of what the function is this is how you would define a doc

this is how you would define a doc string for a

string for a a class and a method so

a class and a method so got the class this is what the class

got the class this is what the class does is this is what the method does

does is this is what the method does and then it's also common to

and then it's also common to add docs place a doc string at the top

add docs place a doc string at the top of the file so if you put a doc string

of the file so if you put a doc string at the top of the file it's going to

at the top of the file it's going to look like this

look like this and it's going to explain what the file

and it's going to explain what the file is all about

is all about and docs stock strings can also span

and docs stock strings can also span multiple lines just like this is a

multiple lines just like this is a multiple line docs string as long as it

multiple line docs string as long as it has the three quarts three quarters at

has the three quarts three quarters at the top three quarts at the bottom

the top three quarts at the bottom and then python will process the doc

and then python will process the doc strings and you can use the help global

strings and you can use the help global function to get the documentation for a

function to get the documentation for a class a method a function or a module

class a method a function or a module for example i'm going to go to the

for example i'm going to go to the bottom of this and i'm going to say

bottom of this and i'm going to say print

print help

help and then i'm just going to type in

and then i'm just going to type in dog now i'll run this

and let me just run it again so now you're going to get information

so now you're going to get information about the dog we know that the dog has a

about the dog we know that the dog has a name and age it's a class representing a

name and age it's a class representing a dog and the has these specific

dog and the has these specific methods

methods and then it says more we can get more

and then it says more we can get more information data descriptors defined

information data descriptors defined here we have

here we have and this is just going to give us all

and this is just going to give us all this information

this information about

about the dog and we and so that's why it's

the dog and we and so that's why it's good to use doc strings because there

good to use doc strings because there are specific standards and it makes it

are specific standards and it makes it easier to get information using

easier to get information using different helper methods

and standards allow and standards allow us to have tools to

and standards allow us to have tools to extract doc strings and automatically

extract doc strings and automatically generate documentation for your code so

generate documentation for your code so besides just this help functions there's

besides just this help functions there's a lot of other methods to pull out these

a lot of other methods to pull out these docs strings and get information about

docs strings and get information about your code and next we will learn about

your code and next we will learn about annotations

annotations python is dynamically typed so we do not

python is dynamically typed so we do not have to specify the type of a variable

have to specify the type of a variable or function parameter or a function

or function parameter or a function return value

return value annotations allow us to optionally do

annotations allow us to optionally do that so if we want to actually show what

that so if we want to actually show what type we're expecting for different

type we're expecting for different values so here's a function without

values so here's a function without annotations and then here's how we would

annotations and then here's how we would make it have annotations so uh we want

make it have annotations so uh we want to make this function only accept an int

to make this function only accept an int so i'm going to put colon int

so i'm going to put colon int and then after here

and then after here i'm going to put

i'm going to put actually before the colon here i'm going

actually before the colon here i'm going to put a little arrow here

to put a little arrow here and then i'm going to put in int so now

and then i'm going to put in int so now we're specifying that this function

we're specifying that this function receives an int and then it's also going

receives an int and then it's also going to

to return an end

return an end and you can do the same thing with

and you can do the same thing with variables so if we have a variable if i

variables so if we have a variable if i had a variable called count and was

had a variable called count and was equal to zero i can add an annotation to

equal to zero i can add an annotation to make it be an int like that so now

make it be an int like that so now we're specifying that this variable is

we're specifying that this variable is going to be an integer

going to be an integer python will actually ignore these

python will actually ignore these annotations a separate tool called mypi

annotations a separate tool called mypi can be run standalone or integrated by

can be run standalone or integrated by ides to automatically check for type

ides to automatically check for type errors statically while you're coding

errors statically while you're coding it'll also help you catch tight

it'll also help you catch tight mismatched bugs before even running the

mismatched bugs before even running the code

code a great help especially when your

a great help especially when your software becomes large and you need to

software becomes large and you need to refactor your code

refactor your code okay now we'll talk about exceptions

okay now we'll talk about exceptions [Music]

[Music] it's important to have a way to handle

it's important to have a way to handle errors and python gives us exception

errors and python gives us exception handling to do so so for exception

handling to do so so for exception handling you would wrap lines of code in

handling you would wrap lines of code in a try block

a try block and then inside this block you'll put

and then inside this block you'll put the lines of code and then if an error

the lines of code and then if an error occurs

occurs python will alert you and you can

python will alert you and you can determine which kind of error occurred

determine which kind of error occurred using an accept block so

using an accept block so we're we're trying some lines of code

we're we're trying some lines of code here and then we're checking for a

here and then we're checking for a specific error and then if that error

specific error and then if that error happens we would handle that error but

happens we would handle that error but if a different error happens then we

if a different error happens then we will handle the different error you can

will handle the different error you can also catch

also catch all exceptions

all exceptions using an accept without an error type so

using an accept without an error type so at the very end you could just do accept

at the very end you could just do accept and then if you don't have an error type

and then if you don't have an error type then it's going to handle the rest of

then it's going to handle the rest of the exceptions and just to make this

the exceptions and just to make this clear this is just an example where it

clear this is just an example where it says air one you have to put a specific

says air one you have to put a specific error in that spot

error in that spot you can also put an else block at the

you can also put an else block at the end to handle that that will run if the

end to handle that that will run if the no exceptions are found so if there are

no exceptions are found so if there are no errors in this code that's right up

no errors in this code that's right up here we can have an else and then run

here we can have an else and then run specific code at the bottom that that

specific code at the bottom that that runs if there's no errors

runs if there's no errors and then we can have a finally block so

and then we can have a finally block so anything

anything in a finally block is going to just

in a finally block is going to just always run at the end whether or not

always run at the end whether or not there are exceptions or no exceptions

there are exceptions or no exceptions the code in the final block is always

the code in the final block is always going to run the specific error that's

going to run the specific error that's going to occur depends on the operation

going to occur depends on the operation you're performing for example if you're

you're performing for example if you're reading a file you might get an eof

reading a file you might get an eof error would just look like this eof

error would just look like this eof error which means end of file

error which means end of file if you divide a number by zero you'll

if you divide a number by zero you'll get a zero division error if you have a

get a zero division error if you have a type conversion issue you might get a

type conversion issue you might get a type error so

type error so let's try this code

let's try this code so i'm going to just delete all this and

so i'm going to just delete all this and we'll do result

we'll do result equals 2 divided by

equals 2 divided by 0 which

0 which you cannot do

you cannot do so just print the result

so just print the result and if i run that

and if i run that we'll see this error over here

we'll see this error over here zero division error division by zero so

zero division error division by zero so it's going to get an error when we run

it's going to get an error when we run the code and then whenever there's an

the code and then whenever there's an error anything after the error occurs

error anything after the error occurs will not happen so we're not going to

will not happen so we're not going to print the result because there is

print the result because there is because the this

because the this this line resulted in error so we're not

this line resulted in error so we're not going to run the following line of code

going to run the following line of code so now let's try adding that operation

so now let's try adding that operation in a

in a try block

try block so i'm just going to paste it all in

so i'm just going to paste it all in here and so we're putting the operation

here and so we're putting the operation in a try block and then we're expecting

in a try block and then we're expecting a zero division error

a zero division error where we'll print cannot divide by zero

where we'll print cannot divide by zero finally we will set the result to one

finally we will set the result to one and then print the results so let me

and then print the results so let me just run that code see cannot divide by

just run that code see cannot divide by zero and then we print one we because we

zero and then we print one we because we set it in the final block here

set it in the final block here so this try block lets us recover

so this try block lets us recover gracefully and move on with the program

gracefully and move on with the program you can raise exceptions in your own

you can raise exceptions in your own code too using the raise statement so i

code too using the raise statement so i could type in raise

could type in raise and then we can raise an exception

and then we can raise an exception intentionally

intentionally and error

and error so if i just run this

so if i just run this it will say

it will say an error because that's what we typed in

an error because that's what we typed in so you can make it say anything you want

so you can make it say anything you want for your error

for your error and this raises a general exception and

and this raises a general exception and you can and you can intercept it

you can and you can intercept it just like this so i could say

just like this so i could say try

try and then we raise that exception

and then we raise that exception and then we can do accept

and then we can do accept exception

exception as error

as error and then we can print

and then we can print the error

okay if i run that so now instead of we don't see all that

so now instead of we don't see all that red anymore because it's not stopping

red anymore because it's not stopping our program because of the error but

our program because of the error but it's now printing the error message

it's now printing the error message right here

right here just like that

just like that you can also define your own exception

you can also define your own exception class extending from exception so i

class extending from exception so i could do class

could do class dog not

dog not found

found [Music]

[Music] exception

exception and then i will

and then i will extend from exception

extend from exception [Music]

[Music] and then i can just put

and then i can just put pass for this one here let me adjust

pass for this one here let me adjust that

that so

so pass here just means nothing and we must

pass here just means nothing and we must use it when we define a class without

use it when we define a class without methods or a function without code so if

methods or a function without code so if you're not going to put anything so this

you're not going to put anything so this is just an example so i can just put

is just an example so i can just put pass to mean that we're not going to

pass to mean that we're not going to have any code in this

have any code in this so now we can try it out so i'll just

so now we can try it out so i'll just paste that uh so we're going to raise

paste that uh so we're going to raise dog not found exception and then if

dog not found exception and then if we're we're going to

we're we're going to candle this exception and just print dog

candle this exception and just print dog not found so let's try that yep dog nut

not found so let's try that yep dog nut bound because it raised this exception

bound because it raised this exception here we can also actually do something

here we can also actually do something in the exception

in the exception so if i can say print

so if i can say print inside

inside and then i'm going to run that

and then i'm going to run that and i'll do inside and dog not bound the

and i'll do inside and dog not bound the with statement is very helpful to

with statement is very helpful to simplify working with exception handling

simplify working with exception handling for example when working with files each

for example when working with files each time we open a file we must remember to

time we open a file we must remember to close it with makes the process more

close it with makes the process more transparent so let me show you some

transparent so let me show you some example code without the with statement

example code without the with statement so

so we're not going to go into a lot of

we're not going to go into a lot of details about working with files here

details about working with files here but i just want to kind of just give

but i just want to kind of just give this one quick example so if we're going

this one quick example so if we're going to be working with files in python so we

to be working with files in python so we can open the file and then we can read

can open the file and then we can read the file we can print the content from

the file we can print the content from the file

the file and we

and we we're going to try that because there

we're going to try that because there could be an exception and then finally

could be an exception and then finally we're always going to make sure to close

we're always going to make sure to close the file

the file but

but an alternate way to do it would be like

an alternate way to do it would be like this

this um so with

um so with we're going to open the file as file and

we're going to open the file as file and then content file.read and then print

then content file.read and then print the content and with using with it's

the content and with using with it's going to make sure to automatically

going to make sure to automatically close the file at the end in other words

close the file at the end in other words we have built-in implicit exception

we have built-in implicit exception handling as close will be called

handling as close will be called automatically for us

automatically for us and with can do a lot more stuff as well

and with can do a lot more stuff as well this example is just meant to introduce

this example is just meant to introduce its capabilities

its capabilities now let's talk about third-party

now let's talk about third-party packages

packages and we're going to talk about pip so

and we're going to talk about pip so let's learn how to install third-party

let's learn how to install third-party packages in python using pip the python

packages in python using pip the python standard library contains a huge number

standard library contains a huge number of utilities that simplify our python

of utilities that simplify our python development needs but nothing can

development needs but nothing can satisfy everything

satisfy everything that's why individuals and companies

that's why individuals and companies create packages and make them available

create packages and make them available as open source software for the entire

as open source software for the entire community so the modules are all

community so the modules are all collected in a single place called the

collected in a single place called the python package index which is available

python package index which is available available at pipe.org that's

available at pipe.org that's pi

pi pi.org

pi.org and they can be installed on the system

and they can be installed on the system using

using pip there's over 270 000 packages freely

pip there's over 270 000 packages freely available

available most computers are already going to have

most computers are already going to have pip installed and it already has pip

pip installed and it already has pip installed so let me show you how you

installed so let me show you how you would install a package we'd have to go

would install a package we'd have to go over to the shell here if you're not on

over to the shell here if you're not on replit you can just do in your terminal

replit you can just do in your terminal and i'm going to clear this here

and i'm going to clear this here and i'm just going to do pip

and i'm just going to do pip install and then you can put the name of

install and then you can put the name of a package for instance one popular

a package for instance one popular package is called the request package

package is called the request package it's an http library so i can do

it's an http library so i can do requests

requests and let me just

and let me just so you can see i have to make sure i

so you can see i have to make sure i spelled that right

spelled that right [Music]

[Music] and it's going to install that package

and it's going to install that package right now so once the we install this

right now so once the we install this package it's going to be available for

package it's going to be available for all our python scripts because packages

all our python scripts because packages are installed globally and the exact

are installed globally and the exact location depends on the operating system

location depends on the operating system you can also upgrade a package to its

you can also upgrade a package to its latest version by doing pip install

latest version by doing pip install dash u and then i will just put the

dash u and then i will just put the package name so in this case we'll just

package name so in this case we'll just do request again

and then it's going to just update it to its

its latest version

latest version in this case

in this case it updated from

it updated from 2.28.0 to 2.28.1

2.28.0 to 2.28.1 you can also specify a specific

you can also specify a specific version when you're installing

version when you're installing and then you can also uninstall a

and then you can also uninstall a package so i'll do pip

package so i'll do pip uninstall

uninstall requests

and then i can say that yes i do want to uninstall that

uninstall that and then once when you have a package

and then once when you have a package installed

installed i'm just going to install request again

and then you always have to make sure you spell it right

you spell it right so once you have it installed you can do

so once you have it installed you can do pip show

pip show requests

requests and then it's going to show some

and then it's going to show some information about the package

information about the package so see we can see the name the version

so see we can see the name the version uh the summary and then a bunch of the

uh the summary and then a bunch of the author and a bunch of other information

author and a bunch of other information about the package

about the package okay i'll just clear this

okay i'll just clear this now we're actually gonna backtrack a

now we're actually gonna backtrack a little bit we already talked about lists

little bit we already talked about lists but i'm gonna talk about a more advanced

but i'm gonna talk about a more advanced way of using lists called

way of using lists called list

list compression

compression list compressions so list compressions

list compressions so list compressions are a way to create lists in a very

are a way to create lists in a very concise way so suppose you have this

concise way so suppose you have this list like this it's a list of numbers

list like this it's a list of numbers and we'll just do

and we'll just do one

one two three

two three four five

four five so we can create a new list using a list

so we can create a new list using a list compression

compression composed by the numbers list elements to

composed by the numbers list elements to the power of 2.

the power of 2. let me show you what i mean so let's get

let me show you what i mean so let's get make a new list numbers

make a new list numbers power

power [Music]

[Music] 2

2 equals

equals and let me just show you how you do this

and let me just show you how you do this list compression

so this is the list compression syntax and if i print this

and if i print this [Music]

[Music] we can see that now we have every

we can see that now we have every element in the list to the power of two

element in the list to the power of two list compressions are a syntax that's

list compressions are a syntax that's sometimes preferred over loops as it's

sometimes preferred over loops as it's more readable when the operation can be

more readable when the operation can be written on a single line

written on a single line so for instance this is how you would do

so for instance this is how you would do it uh with a loop so what we do in a

it uh with a loop so what we do in a single line up here we take a few lines

single line up here we take a few lines to do

to do in the method with a loop so list

in the method with a loop so list compression just makes it

compression just makes it simpler

simpler and then you can do the same thing with

and then you can do the same thing with map as well

map as well but again it's just a little more

but again it's just a little more complex sometimes it's just simpler to

complex sometimes it's just simpler to use a list compression using the syntax

use a list compression using the syntax here

here now let's talk about a few more advanced

now let's talk about a few more advanced topics in regards to functions

topics in regards to functions polymorphism

polymorphism polymorphism generalizes a functionality

polymorphism generalizes a functionality so it can work on different types

so it can work on different types it's an important concept in object

it's an important concept in object oriented programming so see in here

oriented programming so see in here we've defined the same method on

we've defined the same method on different classes so the dog has eat and

different classes so the dog has eat and the cat also has an eat method

the cat also has an eat method then we can generate objects and we can

then we can generate objects and we can call the eat method regardless of the

call the eat method regardless of the class the object belongs to and will get

class the object belongs to and will get different results so we create the two

different results so we create the two objects the dog and the cat here

objects the dog and the cat here and we're calling the eat method on both

and we're calling the eat method on both objects and if we run this you can see

objects and if we run this you can see what we're getting eating cat dog food

what we're getting eating cat dog food eating cat food and so you could do a

eating cat food and so you could do a lot of things with this like maybe you

lot of things with this like maybe you have a list of different animals and

have a list of different animals and then you can

then you can loop through that list and call the eat

loop through that list and call the eat function or the eat method on each

function or the eat method on each animal in that list and they don't have

animal in that list and they don't have to be the exact same class to be able to

to be the exact same class to be able to still run the eat method

still run the eat method so we build a generalized interface and

so we build a generalized interface and now we do not need to know that an

now we do not need to know that an animal is a cat or dog we just need to

animal is a cat or dog we just need to know that we can call eat on it

know that we can call eat on it now let's talk about

now let's talk about operator

operator overloading

overloading [Music]

[Music] operator overloading is an advanced

operator overloading is an advanced technique we can use to make classes

technique we can use to make classes comparable and to make them work with

comparable and to make them work with python operators so let's take this

python operators so let's take this class dog so here's a dog class and you

class dog so here's a dog class and you can create a dog with a name and age

can create a dog with a name and age then we'll create two dog objects we'll

then we'll create two dog objects we'll do roger equals dog

do roger equals dog and we can pass the name

and eight [Music]

[Music] and then i'll make another one

we can use operator overloading to add a custom way to compare these two objects

custom way to compare these two objects based on the age property

based on the age property so like how could you compare

so like how could you compare this dog and this dog well we can make

this dog and this dog well we can make it possible with operator overloading so

it possible with operator overloading so let me just show you this example here

let me just show you this example here so

so this

this function here gt

function here gt is going to compare things as to figure

is going to compare things as to figure out what what is greater than you can

out what what is greater than you can now we'll be able to compare

now we'll be able to compare two dog objects to see which one is

two dog objects to see which one is greater than the other and this is how

greater than the other and this is how we're going to figure out which is

we're going to figure out which is greater than return true if self.age is

greater than return true if self.age is greater than

greater than other dot age which is the other one

other dot age which is the other one you're comparing it to else false

you're comparing it to else false now we can

now we can do print

roger is greater than sid so we're trying to

is greater than sid so we're trying to figure out this is true or false if i

figure out this is true or false if i run this it's going to say true roger is

run this it's going to say true roger is greater than sid because 8 is bigger

greater than sid because 8 is bigger than 7. but if we like put 9 here run

than 7. but if we like put 9 here run that

that now it's going to be false

now it's going to be false so in the same way we define this

so in the same way we define this underscore underscore gt underscore

underscore underscore gt underscore which means greater than we can also

which means greater than we can also define methods for like less than

define methods for like less than lower or equal to greater equal to or

lower or equal to greater equal to or not equal

not equal and then you can also create methods to

and then you can also create methods to go with different arithmetic operators

go with different arithmetic operators so

so we can do add subtract multiply

we can do add subtract multiply division floor division mod power so you

division floor division mod power so you can see all these different ones you can

can see all these different ones you can make it respond to the different

make it respond to the different operators so the example was just a

operators so the example was just a greater than operator but we can

greater than operator but we can make functions to show how it's going to

make functions to show how it's going to respond to all these different

respond to all these different operators there's even a few more

operators there's even a few more methods to work with other operators but

methods to work with other operators but you get the idea we've learned a lot

you get the idea we've learned a lot about python and now we're going to

about python and now we're going to bring a lot of what we've learned

bring a lot of what we've learned together to code a blackjack card game

together to code a blackjack card game and in the process we'll learn about

and in the process we'll learn about object oriented programming in python so

object oriented programming in python so we'll start by creating a new python

we'll start by creating a new python project on replit

and i'm just going to close this tab here

here and i'll zoom in just a bit

and i'll zoom in just a bit and just like our first project

and just like our first project i'm going to

i'm going to say what i'm about to do and i want you

say what i'm about to do and i want you to see if you can do it on your own

to see if you can do it on your own before i show you how to do it

before i show you how to do it and with all you've learned so far a lot

and with all you've learned so far a lot of this you're probably going to be able

of this you're probably going to be able to figure out on your own as i give you

to figure out on your own as i give you the instructions without even seeing how

the instructions without even seeing how i how i do it but then you can come back

i how i do it but then you can come back to the video and see how i do it

to the video and see how i do it or i guess you can just watch and not

or i guess you can just watch and not even try to do it yourself but you're

even try to do it yourself but you're going to learn a lot more if you try to

going to learn a lot more if you try to code this by yourself along with me as i

code this by yourself along with me as i do it but right before i do the

do it but right before i do the different steps

different steps so the first thing we're going to do is

so the first thing we're going to do is create a

create a variable called a suit

variable called a suit and set it equal to hearts and then a

and set it equal to hearts and then a variable called rank and set it to equal

variable called rank and set it to equal k for king

k for king and then a variable called value and set

and then a variable called value and set to equal

to equal 10.

10. [Music]

[Music] okay simple two variables equal to

okay simple two variables equal to strings and one variable equal to an int

strings and one variable equal to an int so now we are going to add a print

so now we are going to add a print statement and print the the phrase your

statement and print the the phrase your card is with a colon at the end

card is with a colon at the end and then we'll add another print

and then we'll add another print statement and print the rank

statement and print the rank so now we're just printing the variable

so now we're just printing the variable here

here and we're going to be doing a lot of

and we're going to be doing a lot of refactoring as we create this program

refactoring as we create this program let's refactor this so it's just one

let's refactor this so it's just one print statement that's going to print

print statement that's going to print your card is colon space and then the

your card is colon space and then the rank

so we are going to be doing string concatenation

string concatenation [Music]

[Music] just like that

just like that so

so you can concatenate as many strings and

you can concatenate as many strings and variables as you want so let's update

variables as you want so let's update the code so that the print function

the code so that the print function print prints your card as

print prints your card as k

k of

of hearts

hearts so we just need to add

so we just need to add of and we have to make sure we put

of and we have to make sure we put spaces on each side of the word of

and then suit

suit and let me just

and let me just adjust this here okay as you know you

adjust this here okay as you know you can use a list in python to store

can use a list in python to store multiple values or items at a time so

multiple values or items at a time so above the suit variable

above the suit variable create a suits

create a suits variable and assign it to a list of

variable and assign it to a list of suits in this case spades clubs hearts

suits in this case spades clubs hearts diamonds

we learned about how you can use the bracket operator to access a specific

bracket operator to access a specific element in a list the number inside the

element in a list the number inside the bracket specifies the index of the list

bracket specifies the index of the list to access remember the indexes start at

to access remember the indexes start at zero

zero so you update the suit variable so that

so you update the suit variable so that the value of hearts come from comes from

the value of hearts come from comes from the suits list

the suits list now we'll practice a for loop so add a

now we'll practice a for loop so add a for loop to the end of the code that

for loop to the end of the code that prints each suit

prints each suit and then we'll just test this out

and then we'll just test this out i really hope you actually are following

i really hope you actually are following along and trying it out right before i

along and trying it out right before i show it to you that's how you're going

show it to you that's how you're going to learn the best here so spades clubs

to learn the best here so spades clubs hearts diamonds

hearts diamonds now this next thing is is just to see if

now this next thing is is just to see if we can do it so it's not going to be

we can do it so it's not going to be part of our final code but right before

part of our final code but right before the loop we just added see if you can

the loop we just added see if you can add another item to the suits list

add another item to the suits list that's the string snakes

there's a few different ways to do it but we will use append snakes so this is

but we will use append snakes so this is just going to append the word snakes at

just going to append the word snakes at the end

the end of the list so if i run this we can now

of the list so if i run this we can now see snakes at the bottom

see snakes at the bottom okay now we're going to start the

okay now we're going to start the process of representing a full deck of

process of representing a full deck of cards with python code

cards with python code so we're going to actually get rid of a

so we're going to actually get rid of a lot of this we're going to get rid of

lot of this we're going to get rid of all this we're just going to have the

all this we're just going to have the suits and then we're going to have this

suits and then we're going to have this for loop at the bottom we're going to do

for loop at the bottom we're going to do a lot of refactoring as we go mainly for

a lot of refactoring as we go mainly for educational purposes but also so we can

educational purposes but also so we can get the a really good blackjack game so

get the a really good blackjack game so we have a list of suits after that we're

we have a list of suits after that we're going to create a list of ranks that's a

going to create a list of ranks that's a 2 3 4 5 6 7 8 9 10 j q

2 3 4 5 6 7 8 9 10 j q k

k [Music]

[Music] now before the suits list

now before the suits list create a new variable called cards and

create a new variable called cards and assign an empty list to the variable

you can an empty list is just two brackets with nothing inside

brackets with nothing inside now in the cards list there should be an

now in the cards list there should be an item for each card in the deck each item

item for each card in the deck each item in the suits list should be combined

in the suits list should be combined with each item in the ranks list for a

with each item in the ranks list for a total of 52 items or cards

total of 52 items or cards let's work our way up to that so first

let's work our way up to that so first we'll update the print statement in the

we'll update the print statement in the for loop so that it prints a list with

for loop so that it prints a list with two elements the first element should be

two elements the first element should be suit and the second should be the first

suit and the second should be the first element of the ranks lists so this

element of the ranks lists so this should print

should print an ace in every suit

so i'm going to update this so it's going to be a list with

going to be a list with suit

suit and ranks

and ranks the first item is going to be at index

the first item is going to be at index zero now let's print that out

so we got them these four right here now instead of just printing an ace in

now instead of just printing an ace in every suit let's print every rank in

every suit let's print every rank in every suit

every suit this can be done easily with a for loop

this can be done easily with a for loop nested within another for loop so inside

nested within another for loop so inside the for loop add another for loop that

the for loop add another for loop that loops through the ranks

loops through the ranks then update the print statement so that

then update the print statement so that it's not just printing the first element

it's not just printing the first element in the ranks list but it's printing the

in the ranks list but it's printing the rank from the for other for loop

rank from the for other for loop so let me show you what i mean

so let me show you what i mean we're going to do four

we're going to do four for rank and ranks

for rank and ranks and then

and then we have to make sure to indent this

we have to make sure to indent this print statement so it's inside this

print statement so it's inside this other for loop

other for loop and this is now just going to be

and this is now just going to be rank so it's going to print the suit and

rank so it's going to print the suit and rank and i'll just run that

rank and i'll just run that and now we with this nested for loop we

and now we with this nested for loop we have every card at every rank in every

have every card at every rank in every suit all 52 cards are printed as two

suit all 52 cards are printed as two item lists

item lists an element in a list can be another list

an element in a list can be another list so instead of printing 52

so instead of printing 52 two item lists

two item lists let's append those 52 cards to the cards

let's append those 52 cards to the cards list

list so we already have the cards list here

so we already have the cards list here it's empty but i'm going to do

it's empty but i'm going to do cards

cards dot

dot append

append and so we're appending

and so we're appending this item

this item all these items to the cards list

all these items to the cards list so let's check what the cards list looks

so let's check what the cards list looks like by printing out printing it out at

like by printing out printing it out at the bottom remember make sure this is

the bottom remember make sure this is not indented at all and we'll do print

not indented at all and we'll do print cards

cards and i'll run that

and then here it is here so this is the list it's not

list it's not one there's just a comma between each

one there's just a comma between each item in the list here

item in the list here you may notice that all the cards are in

you may notice that all the cards are in order in the cards lists

order in the cards lists for a game like this though the cards

for a game like this though the cards must be shuffled so to help with this

must be shuffled so to help with this import the random module at the top of

import the random module at the top of your code so that's just we just do

your code so that's just we just do import

import random

random [Music]

[Music] now we'll be able to use the the random

now we'll be able to use the the random module so this is going to import the

module so this is going to import the random module which contains a variety

random module which contains a variety of things related to random number

of things related to random number generation

generation and as you probably remember when you

and as you probably remember when you import a python module it allows you to

import a python module it allows you to use additional commands in your code

use additional commands in your code specifically we're going to be using the

specifically we're going to be using the random.shuffle function

random.shuffle function so right before at the end where it says

so right before at the end where it says print cards we're going to call

print cards we're going to call random.shuffle and pass in the cards

random.shuffle and pass in the cards list to that function

list to that function and then if i play this here or run the

and then if i play this here or run the program we can see that these are not in

program we can see that these are not in order anymore see ace of spades

order anymore see ace of spades three of spades king of diamonds jack of

three of spades king of diamonds jack of hearts so these are no longer in order

hearts so these are no longer in order because they've been shuffled now let's

because they've been shuffled now let's remove a single element from the cards

remove a single element from the cards list this is similar to dealing a card

list this is similar to dealing a card from a deck and this can be done with

from a deck and this can be done with the pop method

the pop method so after the cards are shuffled

so after the cards are shuffled let's create another card variable and

let's create another card variable and just

just pop off a card from the cards list and

pop off a card from the cards list and put it into that variable called card

put it into that variable called card and just print that card

and just print that card so i'll do card

so i'll do card equals cards dot pop

equals cards dot pop and then instead of printing all the

and then instead of printing all the cards i'm just going to print a single

cards i'm just going to print a single card i'll run the program

card i'll run the program see every time i run the program you can

see every time i run the program you can see we're getting a different card we're

see we're getting a different card we're dealing a different card because it's

dealing a different card because it's been shuffled

been shuffled so we've already learned all about

so we've already learned all about functions and now we're going to create

functions and now we're going to create a function

a function so create a

so create a function called shuffle that just has

function called shuffle that just has the single line that shuffles the cards

the single line that shuffles the cards so it's just def shuffle

so it's just def shuffle and then i just have to make sure this

and then i just have to make sure this is indented so now when we call the

is indented so now when we call the shuffle function it will shuffle the

shuffle function it will shuffle the cards

cards so right before the print statement

so right before the print statement call the shuffle function and instead of

call the shuffle function and instead of just printing the single card print the

just printing the single card print the cards

cards so do shuffle

so do shuffle and then i will print all the cards and

and then i will print all the cards and let's just try out the program

let's just try out the program and we can see there was a problem it's

and we can see there was a problem it's because we didn't put the the colon here

because we didn't put the the colon here so that's an important part of creating

so that's an important part of creating a function is putting the colon there

a function is putting the colon there now we'll create another function called

now we'll create another function called deal and we'll put this line inside the

deal and we'll put this line inside the the deal function

the deal function so we're going to define deal

so we're going to define deal and i'll put the colon this time and

and i'll put the colon this time and make sure to

make sure to indent that

indent that and we can see this has a orange

and we can see this has a orange squiggly line underneath it because

squiggly line underneath it because variables can only be accessed in the

variables can only be accessed in the context that they were created so the

context that they were created so the card variable will not be available

card variable will not be available outside of the deal function

outside of the deal function you can get a value out of a function by

you can get a value out of a function by returning a result using the return

returning a result using the return statement so at the end we're going to

statement so at the end we're going to return the card

okay now we've taken care of that squiggly line there so after the shuffle

squiggly line there so after the shuffle function is called we'll call the deal

function is called we'll call the deal function and assign the return value to

function and assign the return value to a variable named card then we'll update

a variable named card then we'll update the print function to print card instead

the print function to print card instead of cards

of cards so card

so card equals

equals deal

deal and then we'll just print

and then we'll just print the card

and again we see a different card every time we run

see a different card every time we run the program

the program what if you want the deal function to

what if you want the deal function to deal more than one card well let's

deal more than one card well let's refactor the deal function to and accept

refactor the deal function to and accept to accept an argument so any number of

to accept an argument so any number of arguments can appear inside the

arguments can appear inside the parentheses when a function is created

parentheses when a function is created separated by commas inside the function

separated by commas inside the function the arguments are assigned to variables

the arguments are assigned to variables called parameters so start by making it

called parameters so start by making it so we'll start by making it so the deal

so we'll start by making it so the deal function takes an argument named number

function takes an argument named number then we'll make sure when we call the

then we'll make sure when we call the function we use the new parameter

function we use the new parameter by

by making it so we're gonna deal two

making it so we're gonna deal two so i'm just gonna put number here it's

so i'm just gonna put number here it's gonna it's gonna deal a number of cards

gonna it's gonna deal a number of cards we're gonna deal two and i just didn't

we're gonna deal two and i just didn't say this before but now instead this is

say this before but now instead this is not one card anymore so we're going to

not one card anymore so we're going to update this to be cards dealt but

update this to be cards dealt but there's a special shortcut you can

there's a special shortcut you can either it's going to be

either it's going to be command or control d

command or control d and now i'm actually selecting the card

and now i'm actually selecting the card two different times see i i now have

two different times see i i now have multiple cursors here so basically i

multiple cursors here so basically i selected the word i double clicked to

selected the word i double clicked to select the word then did command or

select the word then did command or control d now it's selecting two words

control d now it's selecting two words and now i can type in

and now i can type in cards

cards delt

delt so now i can type in two places at one

so now i can type in two places at one time so that's a cool thing that you can

time so that's a cool thing that you can do in replit and you can do it in many

do in replit and you can do it in many other code editors and i'll run the

other code editors and i'll run the program but it should still only deal

program but it should still only deal one card because even though we're

one card because even though we're passing this parameter into here we're

passing this parameter into here we're not doing anything with it yet here so

not doing anything with it yet here so we want to update the deal function so

we want to update the deal function so it's going to return a list of cards

it's going to return a list of cards instead of a single card

instead of a single card in the first line of the function create

in the first line of the function create an empty list named cards delt then

an empty list named cards delt then update the last line of the function to

update the last line of the function to return cards dealt instead of return

return cards dealt instead of return card so let's do that really quick we're

card so let's do that really quick we're going to do

going to do cards

cards dealt

dealt is going to equal an empty list and i'll

is going to equal an empty list and i'll just copy that and paste it

just copy that and paste it right here

right here now do you remember how to use a the

now do you remember how to use a the range function with a for loop we talked

range function with a for loop we talked about it earlier in the course we just

about it earlier in the course we just briefly touched on it but let's create a

briefly touched on it but let's create a for loop that's going to

for loop that's going to add a card from the deck

add a card from the deck for each

for each card dealt

card dealt so we can do that by creating a for loop

so we can do that by creating a for loop for x and range

for x and range number now this is a common thing you're

number now this is a common thing you're going to be doing in python creating a

going to be doing in python creating a for loop that's going to be in range

for loop that's going to be in range number because now it's going to loop

number because now it's going to loop this many times it's going to loop this

this many times it's going to loop this many times which is the number we passed

many times which is the number we passed in here and we're going to do a few

in here and we're going to do a few things in this for loop

things in this for loop first we are going to

first we are going to actually do this what we already have

actually do this what we already have card equal cards dot pop and then we'll

card equal cards dot pop and then we'll do cards

do cards delt

delt dot append

dot append card

card so now just this card that we popped off

so now just this card that we popped off the deck we are appending it to the

the deck we are appending it to the card's delt and then we're returning the

card's delt and then we're returning the cards dealt here

cards dealt here so down here in the code

so down here in the code let's separate out a single card from

let's separate out a single card from the two cards dealt

the two cards dealt so let's create a variable called card

so let's create a variable called card and set it equal to the first item in

and set it equal to the first item in the cards delt list

the cards delt list and then we'll just print that card

and then we'll just print that card instead of cards dealt

instead of cards dealt so we are going to do card

so we are going to do card equals cards

equals cards delt and then we just use the brackets

delt and then we just use the brackets and put 0 to get the first item in that

and put 0 to get the first item in that list

list and then we'll just print

and then we'll just print a card

a card now i'm just going to test out the

now i'm just going to test out the program we're still just seeing a single

program we're still just seeing a single card here but it's doing a lot more

card here but it's doing a lot more behind the scenes now

behind the scenes now so now let's separate out the rank part

so now let's separate out the rank part of a single card so after we create the

of a single card so after we create the card there let's create a variable named

card there let's create a variable named rank and assign it the rank from the

rank and assign it the rank from the card

card so we'll do rank

so we'll do rank equals card

equals card and then i have to get index one because

and then i have to get index one because the rank is this that's the nine here

the rank is this that's the nine here the second item in this card is the rank

the second item in this card is the rank so each rank has a different value in

so each rank has a different value in blackjack the value of an ace or an a in

blackjack the value of an ace or an a in this in this program is 11

this in this program is 11 or sometimes it can actually be one it's

or sometimes it can actually be one it's going to be 11 or 1 but we'll get to the

going to be 11 or 1 but we'll get to the one part later so jack j q and k which

one part later so jack j q and k which is jack queen and king have the value of

is jack queen and king have the value of 10 and then the numbers have the value

10 and then the numbers have the value of the number so we need to check what

of the number so we need to check what the rank is and set the value depending

the rank is and set the value depending on the rank

on the rank so this is the perfect time for a

so this is the perfect time for a conditional statement specifically an if

conditional statement specifically an if statement

statement before the final print statement or

before the final print statement or program we're going to add an if

program we're going to add an if statement to check if the rank equals a

statement to check if the rank equals a and if so we'll assign 11 to a variable

and if so we'll assign 11 to a variable named value

named value so we'll do if

so we'll do if rank and i hope you remember if you're

rank and i hope you remember if you're flying along i hope you remember to use

flying along i hope you remember to use two equal signs instead of one equal

two equal signs instead of one equal sign here so if rank equals a

sign here so if rank equals a then value is going to equal with a

then value is going to equal with a single equal sign is going to equal

single equal sign is going to equal 11.

11. now if rank does not equal a we'll want

now if rank does not equal a we'll want to check if it equals j q or k

to check if it equals j q or k that can be done with an elif statement

that can be done with an elif statement for now we'll just create an if

for now we'll just create an if statement to check if the rank equals j

statement to check if the rank equals j and then if so we will set the value to

and then if so we will set the value to 10.

so we talked about the three logical operators and or

operators and or and not you can use these three

and not you can use these three operators in conditional statements to

operators in conditional statements to check multiple conditions at once so we

check multiple conditions at once so we want to check if

want to check if rank is j or rank is q

rank is j or rank is q or rank is k so update the code with the

or rank is k so update the code with the the and with the ors

now there can be any number of ls statements after an if statement but at

statements after an if statement but at the end there can only be a single else

the end there can only be a single else statement

statement and like we discussed the else is just

and like we discussed the else is just going to be if none of the other ones

going to be if none of the other ones are true so let's add an else statement

are true so let's add an else statement and inside we'll just assign rank to

and inside we'll just assign rank to value because we've already gotten all

value because we've already gotten all the letters out of the way the rest are

the letters out of the way the rest are numbers and we can assign it directly to

numbers and we can assign it directly to the value

now we'll instead of printing the card at the end

instead of printing the card at the end let's print the rank and the value

let's print the rank and the value so i can just type in rank comma value

so i can just type in rank comma value and

and when that multiple values in a print

when that multiple values in a print statement are listed with a comma

statement are listed with a comma separating them both values are printed

separating them both values are printed with a space in between so let's test

with a space in between so let's test this out a few times q10 five five 6 6

this out a few times q10 five five 6 6 so we can see every time we press it

so we can see every time we press it it's going to be a random rank and value

it's going to be a random rank and value now we already talked about dictionaries

now we already talked about dictionaries in python it's like a list but more

in python it's like a list but more general you can think of a dictionary as

general you can think of a dictionary as a mapping between a set of indices which

a mapping between a set of indices which are called keys and values so key value

are called keys and values so key value pairs each key maps to a value so above

pairs each key maps to a value so above the print statement let's create a

the print statement let's create a variable called rank

variable called rank underscore dict for dictionary and

underscore dict for dictionary and create a dictionary with two items

create a dictionary with two items a key value pair for the rank and a key

a key value pair for the rank and a key value pair for the value

so we have the string rank here and then the actual rank variable string value

the actual rank variable string value and the actual value variable

and the actual value variable before we are

before we are printing the rank variable and the value

printing the rank variable and the value variable but let's update this code so

variable but let's update this code so we're actually getting the rank and

we're actually getting the rank and value from the rank dictionary right

value from the rank dictionary right here

here so i'm going to copy that and then i

so i'm going to copy that and then i just pasted that but now i'm going to

just pasted that but now i'm going to use bracket notation

use bracket notation and so i'll put two brackets but then i

and so i'll put two brackets but then i also have to surround this in quotation

also have to surround this in quotation marks

marks and then i'm gonna

and then i'm gonna put the rank dictionary the brackets

put the rank dictionary the brackets and then the quotation marks because

and then the quotation marks because we're accessing that key there

we're accessing that key there and then i can just run the program and

and then i can just run the program and it's still doing the same thing as

it's still doing the same thing as before just a lot more complicated as

before just a lot more complicated as far as the code goes but it's going to

far as the code goes but it's going to be good to have more complicated code as

be good to have more complicated code as our program is going to become more

our program is going to become more complicated as we go

complicated as we go so when writing a program there are many

so when writing a program there are many ways to do almost everything

ways to do almost everything now we're going to refactor the code to

now we're going to refactor the code to get the value of each rank without using

get the value of each rank without using an if statement

an if statement instead we'll store both the rank name

instead we'll store both the rank name and value in the ranks list using

and value in the ranks list using dictionaries so let's delete all the

dictionaries so let's delete all the code lines of code after where it says

code lines of code after where it says shuffle

shuffle so

so here i know we typed in a lot of stuff

here i know we typed in a lot of stuff there but it was just kind of to

there but it was just kind of to practice and now we're going to practice

practice and now we're going to practice a different method of doing this

a different method of doing this so now let's create a new card variable

so now let's create a new card variable a new variable called card at the end

a new variable called card at the end and let's assign to the card variable

and let's assign to the card variable a a single card that will deal from the

a a single card that will deal from the deck but we'll make sure that card is

deck but we'll make sure that card is not

not in a list so this is a little tricky i'm

in a list so this is a little tricky i'm gonna do deal and i'll deal one card

gonna do deal and i'll deal one card but now i have to get

but now i have to get the first item so this is going to deal

the first item so this is going to deal one card but the one card is going to

one card but the one card is going to deal is going to be in a list so i want

deal is going to be in a list so i want to get the first item in the list which

to get the first item in the list which is going to be the only item in the list

is going to be the only item in the list so i had to put the zero in brackets

so i had to put the zero in brackets here to get that card out of a list

here to get that card out of a list before it goes into the card variable

before it goes into the card variable now we're going to update the ranks list

now we're going to update the ranks list so here's the the ranks list each

so here's the the ranks list each element the list should now be a

element the list should now be a dictionary when lists or list elements

dictionary when lists or list elements are long it's common to put each element

are long it's common to put each element on its own line so we're going to put

on its own line so we're going to put each element on its own line and each

each element on its own line and each element is going to have the rank and

element is going to have the rank and the value so for instance it will be

the value so for instance it will be rank a value 11

rank a value 11 rank 2 value 2.

rank 2 value 2. so it's going to look like

so it's going to look like this

this and i'm now i'm actually going to zoom

and i'm now i'm actually going to zoom out just a little bit and we have all

out just a little bit and we have all these they're all these ranks and each

these they're all these ranks and each one in this list

one in this list is a dictionary each element in the list

is a dictionary each element in the list is a dictionary

is a dictionary okay now that this is updated let's go

okay now that this is updated let's go down and just print a card so we can see

down and just print a card so we can see now that we've updated that ranks list

now that we've updated that ranks list so print

so print card

card okay so this is what it's going to look

okay so this is what it's going to look like coming from

like coming from our list

our list so we got the suit

so we got the suit and then we have the rank that's also

and then we have the rank that's also going to have the value here the rank

going to have the value here the rank and the value

and the value we can see every time we click it we get

we can see every time we click it we get a random item

a random item now let's update the code so instead of

now let's update the code so instead of printing the whole card we just

printing the whole card we just print the value so in this example the

print the value so in this example the value is two so we just want to print

value is two so we just want to print this to just that that value so how can

this to just that that value so how can we update this see if you can figure out

we update this see if you can figure out how to update this line so only prints

how to update this line so only prints just the value number there

just the value number there so first of all we have to see that

so first of all we have to see that we're in a list and we need so this is

we're in a list and we need so this is the first element of the list this is

the first element of the list this is the second element so wait to start by

the second element so wait to start by getting the second element of the list

getting the second element of the list which is

which is index one

index one and then

and then we have an object here or a dictionary i

we have an object here or a dictionary i mean and we need to get

mean and we need to get so here we have this key value pair so

so here we have this key value pair so we need the value at that key so to get

we need the value at that key so to get the value of that key we are going to

the value of that key we are going to put more brackets and i'm going to put

put more brackets and i'm going to put value the key of value so now with that

value the key of value so now with that should work let's try it

should work let's try it okay nine

okay nine seven see every time it's gonna just

seven see every time it's gonna just give us the value of the card

give us the value of the card now we'll start defining classes that

now we'll start defining classes that will be used in order to separate out

will be used in order to separate out different aspects of the game

different aspects of the game so classes you may remember provide a

so classes you may remember provide a way of bundling data and functionality

way of bundling data and functionality together creating a new class creates a

together creating a new class creates a new type of object allowing new

new type of object allowing new instances of that type to be made an

instances of that type to be made an object can contain a number of functions

object can contain a number of functions which we call methods as well as data

which we call methods as well as data that is used by those functions called

that is used by those functions called attributes so

attributes so we're going to use classes to model

we're going to use classes to model three parts of the game a card a deck

three parts of the game a card a deck and a hand so far we've mainly worked on

and a hand so far we've mainly worked on the elements of the debt class

the elements of the debt class so right after this import statement at

so right after this import statement at the top

the top we're going to

we're going to make a class a class called

make a class a class called dec and we're going to put everything

dec and we're going to put everything that we've written so far in that class

that we've written so far in that class so we're just gonna do class

deck colon

colon okay now we just highlight

okay now we just highlight everything here and then i'm gonna press

everything here and then i'm gonna press tab

tab to put everything in the class of deck

to put everything in the class of deck because everything's

because everything's indented a little bit

indented a little bit and then these last few lines of code we

and then these last few lines of code we don't need so i'll just delete those

don't need so i'll just delete those those are just for testing out

those are just for testing out a class is like a template you can use

a class is like a template you can use that class to create an instance of the

that class to create an instance of the class called an object

class called an object then you can use the instance each

then you can use the instance each instance keeps track of its own state so

instance keeps track of its own state so you can update an instance created from

you can update an instance created from a class and it won't impact other

a class and it won't impact other objects created from the same class soon

objects created from the same class soon you'll see an example of all this to

you'll see an example of all this to make it easier to understand

make it easier to understand but first let's prepare a class to

but first let's prepare a class to create an instance from it

create an instance from it when you create an instance of a class

when you create an instance of a class python automatically calls a function

python automatically calls a function also called a method in the clast named

also called a method in the clast named init remember we already discussed this

init remember we already discussed this earlier in the course so the contents of

earlier in the course so the contents of this init method should be code that is

this init method should be code that is run one time to initialize the instance

run one time to initialize the instance so at the beginning of our class let's

so at the beginning of our class let's create this init function so we'll do

create this init function so we'll do def

def underscore underscore init

underscore underscore init underscore underscore and if you

underscore underscore and if you remember from before we always have to

remember from before we always have to pass in

pass in self

self to all of these

to all of these functions in a class because then it

functions in a class because then it gets itself is referring to the instance

gets itself is referring to the instance of the class that we've developed now

of the class that we've developed now we're going to indent all the code

we're going to indent all the code that's not part of the shuffle or deal

that's not part of the shuffle or deal function so the code will be part of

function so the code will be part of this new function so i'm just going to

this new function so i'm just going to highlight

highlight all this here

all this here including

including the suits here and then just press

the suits here and then just press tab

tab so like i said we just added self in

so like i said we just added self in here you should always

here you should always all the methods in a class or all the

all the methods in a class or all the functions should have self

functions should have self anything inside the parentheses remember

anything inside the parentheses remember is called an argument their variables

is called an argument their variables pass them from the color to the

pass them from the color to the functions

functions as i've said all functions in a class

as i've said all functions in a class should receive self as an argument and

should receive self as an argument and self represents the instance of the

self represents the instance of the class by using the self keyword the

class by using the self keyword the function can access the attributes and

function can access the attributes and methods of the class

methods of the class so let's make sure to add self as the

so let's make sure to add self as the first item in the parentheses of the

first item in the parentheses of the other functions

other functions so we are going to add self here

so we are going to add self here and then see how we already have number

and then see how we already have number here but we're going to hit self at the

here but we're going to hit self at the beginning

beginning and we so we can still

and we so we can still call this function with just

call this function with just a single number but it's going to also

a single number but it's going to also get a reference to the instance here now

get a reference to the instance here now i want you to notice that

i want you to notice that the cards here is underlying in

the cards here is underlying in red so before it wasn't when we were

red so before it wasn't when we were before we made this into a class we

before we made this into a class we could just access

could just access this cards variable but now we cannot so

this cards variable but now we cannot so let's fix that

let's fix that inside a class in order to access a

inside a class in order to access a variable in multiple functions also

variable in multiple functions also called methods the variable has to start

called methods the variable has to start with self dot

with self dot so we're going to change all instances

so we're going to change all instances of cards in every function to self.card

of cards in every function to self.card starting

starting with this so self dot cards

with this so self dot cards now this is going to make it so we can

now this is going to make it so we can access it in other places and then we'll

access it in other places and then we'll change this to self dot cards

change this to self dot cards and then this is self

dot cards and then self

and then self dot cards

so now this will be a variable that's specifically associated with the

specifically associated with the instance of the deck that's created and

instance of the deck that's created and then we can access it in all of these

then we can access it in all of these other methods

other methods okay we can now create an instance also

okay we can now create an instance also called an object of the deck class so at

called an object of the deck class so at the very end of the code

the very end of the code let's create a variable called deck 1

let's create a variable called deck 1 and make it an instance of the deck

and make it an instance of the deck class

so to make sure i'm not indented at all and i'll do deck

and i'll do deck 1

1 equals

deck there we go now since we created cards with

now since we created cards with self.cards

self.cards we can access that we can access cards

we can access that we can access cards from the instance of the class so let's

from the instance of the class so let's just print out the cards from our deck

just print out the cards from our deck one so do print

one so do print deck

deck one dot cards

and we can try that out now you can see the the list of all of these cards

the the list of all of these cards it has the suit

it has the suit and the rank and the value for each card

and the rank and the value for each card so underneath where we created deck one

so underneath where we created deck one let's create deck two we'll create

let's create deck two we'll create another instance of another deck

another instance of another deck so

so [Music]

[Music] so now we can call methods on these

so now we can call methods on these instances and you see some of the

instances and you see some of the methods we have we have shuffle and deal

methods we have we have shuffle and deal so on deck 2 right after we create the

so on deck 2 right after we create the deck 2 let's shuffle the deck so deck

deck 2 let's shuffle the deck so deck 2 dot shuffle

2 dot shuffle and then i have to make sure to put the

and then i have to make sure to put the parentheses

parentheses at the end here

at the end here right if we print deck one let's print

right if we print deck one let's print deck two or the cards of deck two so i'm

deck two or the cards of deck two so i'm gonna copy that and then we'll print

gonna copy that and then we'll print deck two cards so now we should see that

deck two cards so now we should see that the deck one cards are not shuffled and

the deck one cards are not shuffled and the deck two cards are shuffled so let

the deck two cards are shuffled so let me move this over here i'm gonna run the

me move this over here i'm gonna run the program

program and let's see if we can see that where

and let's see if we can see that where deck one so here's where here's deck one

deck one so here's where here's deck one and we can see how it's all diamonds

and we can see how it's all diamonds diamonds diamonds diamonds diamonds all

diamonds diamonds diamonds diamonds all the diamonds are in a row because

the diamonds are in a row because unshuffled but then if we go into deck 2

unshuffled but then if we go into deck 2 we can see we have diamonds clubs spades

we can see we have diamonds clubs spades diamonds hearts so these are shuffled in

diamonds hearts so these are shuffled in deck 2 they are shuffled

deck 2 they are shuffled okay the deck works

okay the deck works now let's add safeguards to prevent

now let's add safeguards to prevent errors every time the deal function is

errors every time the deal function is called a card is removed from the cards

called a card is removed from the cards list

list you can only remove a card if there are

you can only remove a card if there are cards to remove

cards to remove so before the program tries to pop a

so before the program tries to pop a card off self.cards is to check if the

card off self.cards is to check if the length of self.cards is greater than

length of self.cards is greater than zero

zero remember you can get the number of items

remember you can get the number of items in a list with length so see if you can

in a list with length so see if you can figure that out on your own and then i'm

figure that out on your own and then i'm about to show you how it's done

about to show you how it's done so when it's going to deal here

so when it's going to deal here right as we're dealing we're going to

right as we're dealing we're going to add an if statement here so if

add an if statement here so if the length

the length of self dot cards

is greater than zero and we do we don't need this parentheses

and we do we don't need this parentheses here so if the length of self.cards is

here so if the length of self.cards is greater than zero

greater than zero then we will

then we will do this we'll pop up a card and add it

do this we'll pop up a card and add it to the cards dealt if not we just won't

to the cards dealt if not we just won't do anything and then we'll return cards

do anything and then we'll return cards dealt which could be an empty array if

dealt which could be an empty array if there were no cards on the deck

there were no cards on the deck now let's add something to the shuffle

now let's add something to the shuffle function a deck with only one card does

function a deck with only one card does not need to be shuffled so let's add the

not need to be shuffled so let's add the appropriate if statement to the shuffle

appropriate if statement to the shuffle function

function so we'll do

so we'll do if the length of self

if the length of self dot cards

dot cards is

is greater than one

greater than one then we will shuffle and then make sure

then we will shuffle and then make sure i'll make sure to put the

i'll make sure to put the colon there

colon there okay

okay since a card is a separate concept than

since a card is a separate concept than a deck

a deck next we'll make a card class

next we'll make a card class so let's create a card class with an

so let's create a card class with an init function and in that init function

init function and in that init function we'll set self.suit to equal hearts

so hopefully you already tried this i'm going to do class

going to do class card

card and then i will do def

and then i will do def net

net [Music]

[Music] and then after the suit will lose self

and then after the suit will lose self dot rank and set it to a

so currently anytime a card is created it will be an ace of hearts let's

it will be an ace of hearts let's refactor the code so the suit and rank

refactor the code so the suit and rank are specified when a card object is

are specified when a card object is constructed so the init method can take

constructed so the init method can take additional parameters besides self that

additional parameters besides self that are passed into it as objects is

are passed into it as objects is constructed so we'll update it to take

constructed so we'll update it to take suit and rank

suit and rank [Music]

[Music] now we'll create a special method

now we'll create a special method that's underscore underscore str

that's underscore underscore str underscore underscore

when a class has this specific method it's called when print is invoked on an

it's called when print is invoked on an object from the class

object from the class so we want to make it so when we print

so we want to make it so when we print an object from the card class it will

an object from the card class it will print something like 10 of hearts or

print something like 10 of hearts or three of clubs or something like that

three of clubs or something like that so we don't do print here we do return

so we don't do print here we do return it's going to return this to the print

it's going to return this to the print statement it's going to turn self dot

statement it's going to turn self dot rank

rank and then we have to get

and then we have to get the rank

the rank [Music]

[Music] and we do plus

and we do plus and then of or to put a string there

and then of or to put a string there plus

plus self dot suit

self dot suit so now it's going to return the rank

so now it's going to return the rank which is like 2 or a of and then the

which is like 2 or a of and then the suit which is one of these

suit which is one of these so let's just try it out real quick and

so let's just try it out real quick and we go to the bottom we don't need any of

we go to the bottom we don't need any of these to test because we're testing

these to test because we're testing something completely different now let's

something completely different now let's do card one

do card one equals

equals [Music]

[Music] card i'm going to create a card and i

card i'm going to create a card and i have to pass in remember i have to first

have to pass in remember i have to first pass in the suit so how about hearts and

pass in the suit so how about hearts and then i have to pass in the rank but we

then i have to pass in the rank but we want to make it look like these ranks so

want to make it look like these ranks so i'm just going to

i'm just going to copy one of these here

and then after we create the card i can just

after we create the card i can just print

print card one

card one let me clear this and then i'll just run

let me clear this and then i'll just run that j of hearts

that j of hearts oh see i got the j of hearts and feel

oh see i got the j of hearts and feel free to add a few more cards like this

free to add a few more cards like this and test out a few more if you want

and test out a few more if you want okay now we're going to refactor this

okay now we're going to refactor this slightly you remember way toward the

slightly you remember way toward the beginning of this course we talked about

beginning of this course we talked about f strings so f strings allow us to put

f strings so f strings allow us to put variables right within a string do you

variables right within a string do you remember how to do that let's see if you

remember how to do that let's see if you can update this to use enough string

can update this to use enough string so first we're going to create a new

so first we're going to create a new string but we're going to start with the

string but we're going to start with the letter f

letter f and then

and then inside this string we put curly braces

inside this string we put curly braces around

around the

the python code and we don't need these

python code and we don't need these other strings here so

and then an ending string here

ending string here okay it's still showing these um red

okay it's still showing these um red squiggly lines because if i have a

squiggly lines because if i have a double quote around the strings and

double quote around the strings and anytime other quotes are in the middle i

anytime other quotes are in the middle i have to put a different type of quote so

have to put a different type of quote so we're going to use

we're going to use single quotes okay so now we can make

single quotes okay so now we can make this a whole a string but we use the

this a whole a string but we use the brackets to put the variables right

brackets to put the variables right within the string so now we've updated

within the string so now we've updated that to use an f string

that to use an f string so currently in the deck class the last

so currently in the deck class the last line of this init method

line of this init method appends a list as an item to the cards

appends a list as an item to the cards list

list instead of appending

instead of appending suit

suit comma rank

comma rank we'll create and append an instance of

we'll create and append an instance of the card class

the card class then afterwards when a deck is created

then afterwards when a deck is created it's filled with cards

it's filled with cards so it's just like this we're just going

so it's just like this we're just going to delete that i'll put card

to delete that i'll put card and then i'll pass in a suit and they

and then i'll pass in a suit and they rank so now we're passing in

rank so now we're passing in card instances

card instances so we're done with the deck and card

so we're done with the deck and card classes and we created them in such a

classes and we created them in such a way that they could basically be used

way that they could basically be used for any card game

for any card game now let's make a hand class

now let's make a hand class this will represent a hand in the game

this will represent a hand in the game of blackjack so create a hand class and

of blackjack so create a hand class and add an inet method and initialize a

add an inet method and initialize a variable called self.cards that is set

variable called self.cards that is set to an empty list so let's go down here

to an empty list so let's go down here and we can also get rid of all this test

and we can also get rid of all this test code here

code here so the new class is called hand

and we'll also make the hand keep track of the value of the hands a self.value

of the value of the hands a self.value will start it at zero

in this blackjack game there will be a human controlled player and a program

human controlled player and a program controlled dealer so let's add a dealer

controlled dealer so let's add a dealer parameter in the init constructor method

parameter in the init constructor method of the hand class

of the hand class and then when the hand classes create a

and then when the hand classes create a dealer should be set to true or false to

dealer should be set to true or false to keep track of what type of hand it is

keep track of what type of hand it is so i'll pass in the parameter dealer and

so i'll pass in the parameter dealer and then we just have to create a variable

then we just have to create a variable and call dealer and set it to dealer so

and call dealer and set it to dealer so self dot dealer

self dot dealer equals dealer

equals dealer [Music]

[Music] if you remember from before function

if you remember from before function parameters can have default values so we

parameters can have default values so we want to make it so the default value of

want to make it so the default value of dealer is false

dealer is false so then if

so then if we create a hand and we don't set the

we create a hand and we don't set the dealer value it will automatically be

dealer value it will automatically be false

false and i'm just going to take out these

and i'm just going to take out these spaces here to make it smaller here

spaces here to make it smaller here so now a hand can be created

so now a hand can be created let's give it some functionality we'll

let's give it some functionality we'll add an add card method and the method

add an add card method and the method should take a card list as a parameter

and then we need to add that card list to the cards

to the cards so we can use the extend function the

so we can use the extend function the extend method to append each item in

extend method to append each item in card list onto the cards list so it's

card list onto the cards list so it's just going to look like this self dot

just going to look like this self dot cards dot append no extend i mean dot

cards dot append no extend i mean dot extend

extend and then we pass in

and then we pass in card list

card list now let's just add some code to test out

now let's just add some code to test out what we have so far so let's create a

what we have so far so let's create a deck and then we will shuffle the deck

deck and then we will shuffle the deck deck.shuffle

deck.shuffle [Music]

[Music] now we'll create a hand

now we can add cards to the hand so hand dot

dot add

add card

and we will deck dot deal we'll deal two cards into the hand

cards into the hand and then we'll just print

and then we'll just print hand cards

okay so this is what how it printed out i was expecting this to look a little

i was expecting this to look a little different

different because of this function it print it

because of this function it print it should print like that

should print like that but i think the reason is

but i think the reason is because

because this is a list so it's printing a list

this is a list so it's printing a list not an individual card so let's change

not an individual card so let's change this to print an individual card i'll

this to print an individual card i'll print the first card so put zero in

print the first card so put zero in there i'll try it again nine of diamonds

there i'll try it again nine of diamonds and then we can also print the next card

and then we can also print the next card three of hearts

three of hearts and then we can also print both cards if

and then we can also print both cards if we just copy that and do

we just copy that and do hand that cards

hand that cards zero

zero handout cards

handout cards one

one okay ace of hearts and nine of spades so

okay ace of hearts and nine of spades so those are the two cards that were dealt

those are the two cards that were dealt to the hand

to the hand now we'll go back to the hand class and

now we'll go back to the hand class and we'll add the ability to calculate the

we'll add the ability to calculate the value of a hand so let's add a method

value of a hand so let's add a method called calculate value

called calculate value and inside the method we'll set

and inside the method we'll set self.value to zero

now we'll take this one step at a time first let's let's make a for loop that's

first let's let's make a for loop that's going to go through every single card

going to go through every single card and inside the for loop we'll just set

and inside the for loop we'll just set the value

the value of the card to a variable called card

of the card to a variable called card underscore value so i'll do four card

underscore value so i'll do four card and self.cards

okay so we're not doing anything with that yet but we're going to in a second

that yet but we're going to in a second here

here now we want to make sure that this is an

now we want to make sure that this is an integer

integer so let's convert that to an integer if

so let's convert that to an integer if you remember you just use int

you remember you just use int [Music]

[Music] and then put it in print int and then

and then put it in print int and then inside the parentheses we put this value

inside the parentheses we put this value not just getting the card value for each

not just getting the card value for each card is not enough something must be

card is not enough something must be done with the variable so let's add that

done with the variable so let's add that value

value to

to self.value

self.value so we'll do self

so we'll do self dot value

dot value and then if you remember from before we

and then if you remember from before we can use the plus equals to

can use the plus equals to add that to the current value those will

add that to the current value those will do a card

do a card value

value so as you may know in blackjack and ace

so as you may know in blackjack and ace can have the value of either 11 or 1

can have the value of either 11 or 1 depending on what is better for the

depending on what is better for the player so there's a few ways to

player so there's a few ways to implement that in code so we're going to

implement that in code so we're going to do one way that's relatively simple

do one way that's relatively simple first we'll check if the hand has an ace

first we'll check if the hand has an ace so let's first create a variable that

so let's first create a variable that will store whether the

will store whether the hand has an a so just be called hand has

hand has an a so just be called hand has underscore ace we'll set to false and

underscore ace we'll set to false and we'll put it right under here

we'll put it right under here so we'll do

so we'll do has ace and we'll set to false and since

has ace and we'll set to false and since we're only going to be using has ace

we're only going to be using has ace within

within this

this method we don't need to use self that

method we don't need to use self that has ace because we're only using it here

has ace because we're only using it here and now when we're going through the the

and now when we're going through the the list of cards let's check if the the

list of cards let's check if the the rank of a card is an ace and then set

rank of a card is an ace and then set has aced equals true

has aced equals true so i'll do it

so i'll do it if

if card dot rank

card dot rank the rank is going to be equal double

the rank is going to be equal double equal sign if it equals ace

after this entire for loop we're going to check if the card has an

we're going to check if the card has an ace

ace and if the value is over 21

and if the value is over 21 if so then we'll just subtract 10 from

if so then we'll just subtract 10 from the value

the value because that'll be the same as setting

because that'll be the same as setting the ace to equal one instead of 11.

the ace to equal one instead of 11. so we'll just do if has

so we'll just do if has ace

is greater than 21 to self.value

to self.value minus equals

minus equals 10.

10. okay and look at this this is something

okay and look at this this is something i don't think i've discussed yet

i don't think i've discussed yet you could say if has

you could say if has equals true and self.value is greater

equals true and self.value is greater than 21.

than 21. but you can also it's like a shorthand

but you can also it's like a shorthand you don't have to say if has ace equals

you don't have to say if has ace equals true

true if has a because has ace is just going

if has a because has ace is just going to equal true or false you can just say

to equal true or false you can just say if has ace so that's just the same as

if has ace so that's just the same as saying if true or if false

saying if true or if false and so we're seeing if both of these

and so we're seeing if both of these evaluate the true then we will subtract

evaluate the true then we will subtract 10 from the value okay now we'll just

10 from the value okay now we'll just add another method to get the value of a

add another method to get the value of a hand called getvalue and the function

hand called getvalue and the function will just return self.value

will just return self.value so we're going to make sure that we're

so we're going to make sure that we're not we're indented correctly and do def

not we're indented correctly and do def get

get value

value return

return self

self dot value

and then i have to make sure i put the parentheses here

parentheses here and then i have to remember to put self

and then i have to remember to put self since this is a self.value we could call

since this is a self.value we could call down here like we could call

down here like we could call hand

hand value to get the value but it's

value to get the value but it's generally better to make a function to

generally better to make a function to return the value so i can do get

return the value so i can do get value that way there may be some extra

value that way there may be some extra code you want to run in there like

code you want to run in there like depending on different conditions

depending on different conditions you may want to modify the value before

you may want to modify the value before you return it

you return it so it's best practice to create a method

so it's best practice to create a method that will get a value like this for you

so currently this value that's returned could be incorrect

could be incorrect because

because if someone's going to get the value the

if someone's going to get the value the value has to be calculated correctly

value has to be calculated correctly first and like checking for aces and and

first and like checking for aces and and other things so let's call

other things so let's call let's calculate the value before we

let's calculate the value before we return the value so i'm going to do self

return the value so i'm going to do self dot calculate value so

dot calculate value so this is something that i think is new

this is something that i think is new where to call calculate value from

where to call calculate value from within this we're going to have to call

within this we're going to have to call self.calculatevalue

self.calculatevalue and self will refer to the instance that

and self will refer to the instance that we're working with so we're calling the

we're working with so we're calling the calculate value on the instance that's

calculate value on the instance that's that is the the hand instance and we're

that is the the hand instance and we're getting the value and then we're

getting the value and then we're returning the value

returning the value okay let's create another method called

okay let's create another method called is blackjack and it'll return true if

is blackjack and it'll return true if there's a blackjack and false otherwise

there's a blackjack and false otherwise so it's a blackjack if the value is 21.

so it's a blackjack if the value is 21. so i'm gonna do

so i'm gonna do def

def get or is

get or is oh and put self here

oh and put self here okay so this is going to evaluate you to

okay so this is going to evaluate you to either true or false and return true or

either true or false and return true or false depending on whether there's a

false depending on whether there's a blackjack

blackjack now we'll create the final method in the

now we'll create the final method in the hand class that will display information

hand class that will display information about the hand so let's create a method

about the hand so let's create a method called display they'll

called display they'll to start with will just print your hand

to start with will just print your hand [Music]

[Music] okay now let's do a quick refactor

okay now let's do a quick refactor instead of saying your hand it should

instead of saying your hand it should either say dealer's hand or your hand

either say dealer's hand or your hand depending on whether

depending on whether self.dealer

self.dealer is

is true or not

true or not so we're going to you to to do this all

so we're going to you to to do this all in one line we're going to use a few

in one line we're going to use a few things that we learned about earlier

things that we learned about earlier including

including ternary operators

ternary operators f strings and going between double

f strings and going between double quotes and single quotes and then one

quotes and single quotes and then one other new thing we are going to make

other new thing we are going to make this into an f string

this into an f string and then we are going to be using

and then we are going to be using actually

actually single quotes and double quotes within

single quotes and double quotes within this f string so if you want to use

this f string so if you want to use single quotes and double quotes within a

single quotes and double quotes within a string

string then you can surround it with a triple

then you can surround it with a triple single quote so i'm going to delete this

single quote so i'm going to delete this quote and just do three single quotes

quote and just do three single quotes and then delete this quote and do three

and then delete this quote and do three single quotes and so

single quotes and so we got the

we got the double quote

double quote single quote and now this is a triple

single quote and now this is a triple quote so now we can use the double quote

quote so now we can use the double quote and single quotes within this string

and single quotes within this string so i'm going to um i'm just going to

so i'm going to um i'm just going to delete your right here and we are going

delete your right here and we are going to

to put a ternary operator to see if it's

put a ternary operator to see if it's going to say dealers or yours in the

going to say dealers or yours in the dealer's hand or your hand so

dealer's hand or your hand so to do some code i'm going to put these

to do some code i'm going to put these curly braces here

curly braces here and then to do this ternary operator

and then to do this ternary operator we're going to put dealer

we're going to put dealer and now here so here's the double quote

and now here so here's the double quote and here's the single quote so dealers

and here's the single quote so dealers it will

it will return dealers

return dealers if

if self.dealer

so basically if self.dealer equals true so return dealers if self.dealer

so return dealers if self.dealer else will return

else will return your

your okay that's the line so it's going to be

okay that's the line so it's going to be the dealer's hand or your hand and next

the dealer's hand or your hand and next we will add a for loop that will print

we will add a for loop that will print out each of the cards

out each of the cards so

so for card and self.cards

for card and self.cards print

print card

card and then finally if the player is not

and then finally if the player is not the dealer it should print value

the dealer it should print value and then a colon and then print the

and then a colon and then print the value of the cards so to do this we can

value of the cards so to do this we can actually use the the not operator so

actually use the the not operator so if not

if not self.dealer

self.dealer [Music]

then we will print and we'll print value

and we'll print value value

value and then i can just put a comma to print

and then i can just put a comma to print two different items so the string and

two different items so the string and it'll print self dot get

it'll print self dot get value

value and it's gonna when you put a comma and

and it's gonna when you put a comma and two different things it's gonna put a

two different things it's gonna put a space in between

space in between and then finally we'll just add an empty

and then finally we'll just add an empty a print statement that will print a

a print statement that will print a blank line

blank line okay let's test this out by

okay let's test this out by instead of printing this we are going to

instead of printing this we are going to print

print hand

hand dot display

dot display to see if this all works how we thought

to see if this all works how we thought it was going to work

it was going to work so your hand k of spades two of spades

so your hand k of spades two of spades value is 12. so it's actually

value is 12. so it's actually calculating that correctly because

calculating that correctly because that's 10 plus 2 is 12 and then it's

that's 10 plus 2 is 12 and then it's going to print none which indicates that

going to print none which indicates that we did something wrong which is that we

we did something wrong which is that we did not need to print this because hand

did not need to print this because hand display display already prints so now

display display already prints so now just call hand.display

just call hand.display okay so now it doesn't put none or

okay so now it doesn't put none or doesn't yeah it doesn't put none at the

doesn't yeah it doesn't put none at the end so that looks right

end so that looks right okay when you're playing blackjack you

okay when you're playing blackjack you don't get to see

don't get to see everyone else's cards

everyone else's cards so

so we're going to update this so when the

we're going to update this so when the dealer's cards are printed during the

dealer's cards are printed during the game

game only the second one should display

only the second one should display the first card should display as hidden

the first card should display as hidden so in this for loop

so in this for loop when we're displaying the cards

when we're displaying the cards we're going to need to get access to the

we're going to need to get access to the card index since that will determine

card index since that will determine which to display

which to display since we're only going to display the

since we're only going to display the second card

second card so let's start by updating this for loop

so let's start by updating this for loop so we can get access to both the card

so we can get access to both the card and the card index

and the card index we briefly touched on this earlier in

we briefly touched on this earlier in the course we're going to be using the

the course we're going to be using the enumerate function

enumerate function so

so when it's for card in

when it's for card in and now i'm going to type in enumerate

and now i'm going to type in enumerate and i'm going to pass in self.cards

and i'm going to pass in self.cards and this is going to return the index

and this is going to return the index and the card for each card so i'm going

and the card for each card so i'm going to type it index

to type it index comma

comma and so

and so in we're getting the index and the card

in we're getting the index and the card for all the items in self.cards

for all the items in self.cards and so now we just have to update what's

and so now we just have to update what's in the for loop

in the for loop to print

to print hidden

hidden if it's the first card and it's a dealer

if it's the first card and it's a dealer so we'll do

so we'll do if index

if index equals zero and self.dealer

then we will print

and then we can use an else any other time

any other time and let's make sure this lines up

and let's make sure this lines up correctly any other time we will print

correctly any other time we will print the card

the card so

so what we did wrong here is this should be

what we did wrong here is this should be double equal sign i did almost did the

double equal sign i did almost did the the main mistake you always have to

the main mistake you always have to watch out never use a single equal sign

watch out never use a single equal sign when you're checking equality

when you're checking equality because that's the single equal sign is

because that's the single equal sign is the assignment operator so if index

the assignment operator so if index equals zero and self and we it is the

equals zero and self and we it is the dealer then we'll print hidden

dealer then we'll print hidden so in our version of the game at the end

so in our version of the game at the end of the game

of the game that all the dealer's cards will be

that all the dealer's cards will be shown so you can see what the dealer had

shown so you can see what the dealer had so to do that we're going to create a

so to do that we're going to create a new parameter in this

new parameter in this display method and it's going to be

display method and it's going to be called show all dealer cards with

called show all dealer cards with underscores for spaces and we're going

underscores for spaces and we're going to set the default value to false

to set the default value to false show

show all

all dealer

dealer cards

cards and when the default value is going to

and when the default value is going to be false

be false now we'll add it to this if statement

so we'll add another

we'll add another and

and not

not show

show all

all dealer cards

dealer cards so

so it's going to be hidden if we're not

it's going to be hidden if we're not showing all the dealer cards

showing all the dealer cards but if we are showing all the dealer

but if we are showing all the dealer cards then this whole if statement will

cards then this whole if statement will be false so we'll just print the card

be false so we'll just print the card and there's going to be one other

and there's going to be one other scenario where we're not going to print

scenario where we're not going to print hidden if there's a blackjack then the

hidden if there's a blackjack then the game is over the person with the

game is over the person with the blackjack is just going to win and then

blackjack is just going to win and then we'll just print all the cards so we're

we'll just print all the cards so we're going to add that to this long if

going to add that to this long if statement here so we'll say

statement here so we'll say and not is

and not is black jack

black jack and it should be

and it should be self dot is blackjack to be able to call

self dot is blackjack to be able to call this method here

this method here and since this is such a long line is

and since this is such a long line is always going to go to this next line we

always going to go to this next line we can do this special thing

can do this special thing we can add a slash here

we can add a slash here and then just go to the next line

and then just go to the next line so

so this slash or it's a backslash i mean

this slash or it's a backslash i mean this backslash will indicate that the

this backslash will indicate that the line continues on the following line

line continues on the following line okay we're done creating the hand class

okay we're done creating the hand class so we'll delete

so we'll delete everything that we were using for

everything that we were using for testing before

testing before okay it's time to code the final and

okay it's time to code the final and longest class that runs the game so what

longest class that runs the game so what i want you to do is create a class

i want you to do is create a class called game and inside the class create

called game and inside the class create a method called play and inside the

a method called play and inside the method create a variable called

method create a variable called gamenumber with the underscore for the

gamenumber with the underscore for the space

space and set that to zero so class game

and set that to zero so class game and then we'll create another variable

and then we'll create another variable games to play and set that to zero

games to play and set that to zero now we're going to set games to play

now we're going to set games to play to be whatever the user inputs

to be whatever the user inputs after they're asked how many games do

after they're asked how many games do you want to play

you want to play so you may remember how to do

so you may remember how to do input from before

input from before so we just do input

so we just do input now we want to make sure the games to

now we want to make sure the games to play is an end so we just need to

play is an end so we just need to convert this to an end

[Music] okay now let's test things so far so at

okay now let's test things so far so at the end i will put g equals game i'm

the end i will put g equals game i'm going to create a new game

going to create a new game and then g dot play

how many games you want to play five

five okay well it's not going to play the

okay well it's not going to play the games yet we still have to create that

games yet we still have to create that so there is a potential for an error

so there is a potential for an error here if i do this again and i just put

here if i do this again and i just put how many games i put you or some letter

how many games i put you or some letter we're going to get an error

we're going to get an error so basically anytime someone puts

so basically anytime someone puts something that's not a number is going

something that's not a number is going to be an error

to be an error so let's create a try accept block to

so let's create a try accept block to handle the exception

handle the exception and

and if they put something that's not a

if they put something that's not a number we'll

number we'll print you must enter a number so let me

print you must enter a number so let me arrange this and we've already learned a

arrange this and we've already learned a little bit about try except blocks i'm

little bit about try except blocks i'm going to put try

going to put try and it's going to try this

and it's going to try this and then if that doesn't work if there's

and then if that doesn't work if there's an exception

an exception [Music]

[Music] it will print

it will print [Music]

[Music] you must enter a number

you must enter a number so currently the user gets only one

so currently the user gets only one chance to input a correct value let's

chance to input a correct value let's make the program keep asking the user

make the program keep asking the user for a value until the user enters a

for a value until the user enters a number this can be done with a while

number this can be done with a while loop the while loop just keeps looping

loop the while loop just keeps looping while something is true so keep looping

while something is true so keep looping until the user enters a number by

until the user enters a number by putting the entire tri-catch block into

putting the entire tri-catch block into a while loop that keeps looping while

a while loop that keeps looping while the game's a play is less than or equal

the game's a play is less than or equal to zero

to zero [Music]

[Music] oh and i have to make sure i spell

oh and i have to make sure i spell while correctly

while correctly okay now let's create the main game loop

okay now let's create the main game loop this is a new loop that will loop one

this is a new loop that will loop one time per game played it should loop

time per game played it should loop while game number is less than games to

while game number is less than games to play and the first line of loop should

play and the first line of loop should increment the game number by one

inside the loop we'll create a deck object in a deck variable and shuffle

object in a deck variable and shuffle the deck

the deck now we'll create a variable called

now we'll create a variable called playerhand and set it to a hand object

playerhand and set it to a hand object and then we'll create a variable called

and then we'll create a variable called dealerhand and set it to a hand object

dealerhand and set it to a hand object but this time we'll make sure to specify

but this time we'll make sure to specify that dealer equals true

okay this next part will be a little more complicated we'll create a for loop

more complicated we'll create a for loop that loops two times and each iteration

that loops two times and each iteration should add a card to the player's hand

should add a card to the player's hand that is dealt from the deck and add a

that is dealt from the deck and add a card to the dealer's hand that is also

card to the dealer's hand that is also dealt from the deck

dealt from the deck [Music]

[Music] okay we just dealt two cards each player

okay we just dealt two cards each player now information is going to be printed

now information is going to be printed to the console for each game so let's

to the console for each game so let's start by printing an empty line

start by printing an empty line now we'll print an asterisk 30 times to

now we'll print an asterisk 30 times to make a divider

make a divider there's a trick to printing something a

there's a trick to printing something a lot of times so i can put an asterisk

lot of times so i can put an asterisk in in quotation marks and then just do

in in quotation marks and then just do times 30.

times 30. so it's going to print it 30 times now

so it's going to print it 30 times now we'll print the current game number out

we'll print the current game number out of the total number of games

of the total number of games so it'll be something like game 4 of 10

and we'll use an f string and then we'll just print 30 more

and then we'll just print 30 more asterisks

now we'll display the player's hand and then the dealer's hand

and then the dealer's hand at this point in the game someone could

at this point in the game someone could already have won if they got a blackjack

already have won if they got a blackjack the code should check if there's a

the code should check if there's a winner let's put the code to check if

winner let's put the code to check if there's a winner in a separate method of

there's a winner in a separate method of the game class so create a method called

the game class so create a method called check winner for now the method should

check winner for now the method should just return false

and just make sure everything's indented correctly this should be less indented

correctly this should be less indented than the previous line here

than the previous line here the check winner function should take

the check winner function should take the playerhand and dealer hand as

the playerhand and dealer hand as arguments

now before this return statement we're going to check if

we're going to check if playerhand.getvalue is greater than 21.

playerhand.getvalue is greater than 21. if so we'll print you busted dealer wins

if so we'll print you busted dealer wins and then return true and remember once

and then return true and remember once the program gets to a return statement

the program gets to a return statement none of the following statements in the

none of the following statements in the block are run

block are run [Music]

now we'll use a few lf statements to check for various other conditions so

check for various other conditions so we'll add an lf statement to see if the

we'll add an lf statement to see if the dealer got over 21

dealer got over 21 and then we'll print dealer busted you

and then we'll print dealer busted you win and then return true

win and then return true [Music]

[Music] oh and i just copied all this but this

oh and i just copied all this but this should be an l if not if

should be an l if not if and then we'll add an lf statement to

and then we'll add an lf statement to check if both players have a blackjack

check if both players have a blackjack and then we'll print both players have a

and then we'll print both players have a blackjack tie

blackjack tie and then return true

[Music] and then we'll add an elf statement to

and then we'll add an elf statement to check if player hand has a blackjack and

check if player hand has a blackjack and then we'll print you have blackjack you

then we'll print you have blackjack you win

win and then return true

and then we'll check if the dealer hand has a blackjack and then say dealer has

has a blackjack and then say dealer has blackjack dealer wins

blackjack dealer wins and return true

and return true [Music]

[Music] okay we're done with all the hand when

okay we're done with all the hand when conditions but the game can also end if

conditions but the game can also end if both players choose not to get more

both players choose not to get more cards so we're going to add a new

cards so we're going to add a new argument to the check winner method with

argument to the check winner method with a default value it's going to be game

a default value it's going to be game over equals false

over equals false so we'll add game

so we'll add game over

over equals false

equals false if it's true that means both players

if it's true that means both players have chosen not to get more cards now

have chosen not to get more cards now we'll use the new argument

we'll use the new argument the string of if and lf statements

the string of if and lf statements should only be run

should only be run if it's not a game over and we'll make

if it's not a game over and we'll make sure the line returned false is not in

sure the line returned false is not in the if statement

the if statement so

so here we'll say

here we'll say if

if not game

not game over

over and then i'll just select all these and

and then i'll just select all these and put them

put them in here

in here so if game over is true we'll check if

so if game over is true we'll check if the player hand's value is more than the

the player hand's value is more than the deal hands value and if so we'll print

deal hands value and if so we'll print you in

you in so we can do this with an else here

so we can do this with an else here else

else if player

if player [Music]

[Music] and then we'll do an lf for if it's a

and then we'll do an lf for if it's a tie

so this is an lf and we'll say if these are

and we'll say if these are equal to each other

equal to each other and we'll print

and we'll print tie

and then make sure we have the correct emoji for a tie

emoji for a tie [Music]

[Music] and then else the dealer is one

and then else the dealer is one so we'll just do

so we'll just do else

else [Music]

[Music] and then at the exact same level of

and then at the exact same level of indentation as the else we just added

indentation as the else we just added we'll add return true this will make the

we'll add return true this will make the method return true if game over equals

method return true if game over equals true

true now let's go back to the play method

now let's go back to the play method inside the while loop

inside the while loop and then we'll do an if statement and

and then we'll do an if statement and we'll do if and then we'll call the

we'll do if and then we'll call the check winner function with the player

check winner function with the player hand and the dealer hand so let's go

hand and the dealer hand so let's go back up here

winner and then we'll enter the player hand and

and then we'll enter the player hand and the dealer hand

the dealer hand [Music]

[Music] so if this is true that means we should

so if this is true that means we should go on to the next game

go on to the next game to do that we do continue

to do that we do continue so continue is going to just go to the

so continue is going to just go to the next iteration of the loop and the loop

next iteration of the loop and the loop we're on is this loop so when we go to

we're on is this loop so when we go to the next iteration we start a new game

the next iteration we start a new game at this point in the game the player

at this point in the game the player will be able to choose hit or stand

will be able to choose hit or stand so inside the while loop but not inside

so inside the while loop but not inside the if statement we just added we'll

the if statement we just added we'll create a variable called choice and set

create a variable called choice and set it to be an empty string

the player should be able to keep choosing until the value of their hand

choosing until the value of their hand is over 21. so right under the choice

is over 21. so right under the choice variable we'll add a while loop that

variable we'll add a while loop that loops while player hand's value is less

loops while player hand's value is less than 21 and inside the loop we'll add a

than 21 and inside the loop we'll add a line to get the choice

line to get the choice that's either going to be hit or stand

and then we'll just add this to convert whatever the answer is whatever the user

whatever the answer is whatever the user put in we are going to convert it to

put in we are going to convert it to lowercase

lowercase the while loop we just added should also

the while loop we just added should also stop if the user's choice is stand or or

stop if the user's choice is stand or or s so we'll update the line that starts

s so we'll update the line that starts the while loop to also stop if the

the while loop to also stop if the choice isn't s or stand so just do and

choice isn't s or stand so just do and choice

choice not in

not in and this is there's a few ways to do it

and this is there's a few ways to do it but this is kind of a new way that i'm

but this is kind of a new way that i'm just showing you here

just showing you here [Music]

[Music] so we are checking if choice is not in

so we are checking if choice is not in this list and inside the list we have

this list and inside the list we have two elements s or stand so if choice is

two elements s or stand so if choice is not in that if the choice is not s or

not in that if the choice is not s or stand then we'll continue the loop

stand then we'll continue the loop and then after the input we'll print an

and then after the input we'll print an empty line

also we want the program to keep asking the user for a choice until the user

the user for a choice until the user enters a valid choice

enters a valid choice the valid choices are hs hit and stand

the valid choices are hs hit and stand so right after the last print statement

so right after the last print statement at the same indentation we'll add a

at the same indentation we'll add a while loop that will keep looping until

while loop that will keep looping until the user enters a valid choice

the user enters a valid choice and inside that while loop we'll ask for

and inside that while loop we'll ask for input again

input again but we'll specify it can be h or s as

but we'll specify it can be h or s as well

well [Music]

[Music] so this is going to look very similar to

so this is going to look very similar to this line but it's going to kind of

this line but it's going to kind of clarify things just a little bit

clarify things just a little bit and then we'll print another empty line

and then we'll print another empty line the last while loop we checked if choice

the last while loop we checked if choice was not in a list

was not in a list outside of the recently added a while

outside of the recently added a while loop but inside the loop we just added

loop but inside the loop we just added before that one we'll add an if

before that one we'll add an if statement to check if choice is in the

statement to check if choice is in the list hit or h and if so we'll add a card

list hit or h and if so we'll add a card to the player's hand that is dealt from

to the player's hand that is dealt from the deck

and then right below that will display the player's hand

outside all the while loops about the player making a choice we'll check for a

player making a choice we'll check for a winner we'll use the same if statement

winner we'll use the same if statement and continue statement that we use last

and continue statement that we use last time we checked for winner so i'll just

time we checked for winner so i'll just copy this

copy this and then

and then we have to make sure it's lined up

we have to make sure it's lined up correctly

correctly okay so this is outside of this while

okay so this is outside of this while loop so after this all is all done we

loop so after this all is all done we check for a winner let's just add an

check for a winner let's just add an empty line there to

empty line there to make it more clear that the while loop

make it more clear that the while loop is over

is over now we'll store the value of the

now we'll store the value of the player's hand in a variable named player

player's hand in a variable named player hand value with underscores for spaces

hand value with underscores for spaces [Music]

[Music] and we'll do the same thing with the

and we'll do the same thing with the dealer's hand

dealer's hand [Music]

[Music] remember i could use the command d or

remember i could use the command d or control d to select two words at once

control d to select two words at once and change them both at the same time

and change them both at the same time okay the dealer should keep drawing

okay the dealer should keep drawing cards until dealer hand value is more

cards until dealer hand value is more than 17 so we'll make this happen with a

than 17 so we'll make this happen with a while loop

while loop and inside the loop we'll make sure the

and inside the loop we'll make sure the dealer is dealt a card from the deck and

dealer is dealt a card from the deck and that dealer hand value is updated

that dealer hand value is updated so you can try that yourself but i'm

so you can try that yourself but i'm going to show you right now while

going to show you right now while dealer

dealer hand value

hand value is less than 17.

is less than 17. then we will do dealer

then we will do dealer hand dot

hand dot add card

okay and after this while loop will display the dealer's hand and when we

display the dealer's hand and when we call the display method we'll make sure

call the display method we'll make sure to set show all dealer cards to true

[Music] and since it's the end of the game

and since it's the end of the game that's why we're just showing all the

that's why we're just showing all the cards

cards now we'll check for a winner just like

now we'll check for a winner just like before

then we'll print your hand colon and then the player hand value

then the player hand value [Music]

[Music] and then the dealer's hand

now we'll call the check winner function one final time

one final time but this time it should not be an if

but this time it should not be an if statement and we'll pass in the hands

statement and we'll pass in the hands like before but this time we'll add a

like before but this time we'll add a third argument of true to indicate that

third argument of true to indicate that the game is over

and at this point in the code the game is over

is over so outside the outer while loop and in

so outside the outer while loop and in the play method we'll add the final line

the play method we'll add the final line of saying

of saying thanks for playing

so it's going to be outside that while loop and we'll put print

and just to demonstrate it i use an escape character to add a new line so

escape character to add a new line so this slash in is going to add a new line

this slash in is going to add a new line and then do thanks for playing and when

and then do thanks for playing and when i line this up for with the while loop i

i line this up for with the while loop i realize that this entire function should

realize that this entire function should not be lined up with the while loop

not be lined up with the while loop sometimes it gets tricky with um

sometimes it gets tricky with um figuring out the exact right indentation

figuring out the exact right indentation so if i

so if i kind of go up straight up here

kind of go up straight up here i should say see that this should be

i should say see that this should be lined up with this play function

lined up with this play function so i'm going to come back down to this

so i'm going to come back down to this function

function i'm going to

i'm going to copy this all

copy this all and i'm just going to do shift tab

and i'm just going to do shift tab to indent it all one less

to indent it all one less this happens sometimes when running

this happens sometimes when running python code sometimes the indentation

python code sometimes the indentation can get all mixed up but that should be

can get all mixed up but that should be correct now and i think the red squiggly

correct now and i think the red squiggly lines here on the return true are not a

lines here on the return true are not a mistake in the code but a mistake in the

mistake in the code but a mistake in the error checking because it comes after

error checking because it comes after that emoji and it doesn't know how to

that emoji and it doesn't know how to handle the emoji but it's perfectly fine

handle the emoji but it's perfectly fine for code to have emojis okay let's run

for code to have emojis okay let's run the program and try it out so i'll press

the program and try it out so i'll press play how many games i want to play i'll

play how many games i want to play i'll do three

do three so game of one of three so i can see i

so game of one of three so i can see i have 17 i don't know what the dealer has

have 17 i don't know what the dealer has but i'm going to s for stand

but i'm going to s for stand okay it's always good to test so it says

okay it's always good to test so it says deal is missing one required positional

deal is missing one required positional argument so let's go up to

argument so let's go up to it says line 139 so this can kind of

it says line 139 so this can kind of help us know where to go so let's go up

help us know where to go so let's go up to 139

and yeah i want to deal a single card so i'm going to deal one card here

i'm going to deal one card here and

and were there any other times i did use

were there any other times i did use deal

i want to deal one card here

and yeah i got the deal one up here so i

yeah i got the deal one up here so i just think i just forgot the deal one in

just think i just forgot the deal one in those places

those places so uh thanks to these error messages

so uh thanks to these error messages whenever you have a problem make sure to

whenever you have a problem make sure to read the error messages and it can often

read the error messages and it can often give you a very good idea of what you

give you a very good idea of what you need to do wrong because even says deal

need to do wrong because even says deal is missing one required positional

is missing one required positional argument the number so that can really

argument the number so that can really help figure out what's wrong with your

help figure out what's wrong with your code so let's try that again we'll do

code so let's try that again we'll do three games

three games and then this time i will hit

and then this time i will hit and i'm going to stand

and i'm going to stand okay so now we have another error

okay so now we have another error so it says 173

so it says 173 and oh this i can already see this is

and oh this i can already see this is spelled wrong so let's go to

spelled wrong so let's go to 173

and make sure i spell that correctly

make sure i spell that correctly and make sure i spell that correctly

and make sure i spell that correctly okay let's try again

okay let's try again how many games you want to play three

how many games you want to play three i'm going to hit

i'm going to hit and hit

and hit okay so the first game

okay so the first game you busted dealer wins and now we're on

you busted dealer wins and now we're on game number two i'll hit

game number two i'll hit and this time i will stand

and this time i will stand okay dealer busted you win now we're on

okay dealer busted you win now we're on game three of three

game three of three and i will hit

and i will hit and i will stand

and i will stand and final results your hand 20 dealer's

and final results your hand 20 dealer's hand 19

hand 19 you win

you win thanks for playing

thanks for playing we just completed this whole game

we just completed this whole game okay we've reached the end of the course

okay we've reached the end of the course so you've learned the basics of python

so you've learned the basics of python and if you've been coding along you've

and if you've been coding along you've written two python programs good luck on

written two python programs good luck on your programming journey thanks for

your programming journey thanks for watching and remember use your code for

watching and remember use your code for good bye bye bye

good bye bye bye bye bye

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Python for Beginners – Full Course [Programming Tutorial]