these are my notes from BroCode's python course on youtube, formatted in markdown for readability. i'm creating these notes to refer back to them in the future, and they might also benefit others following the course. good luck to everyone!
print("hello world")- a variable is a container for a value, it behaves as the value that it contains.
name = "Bro"
print(type(name))
print("Hello " + name)first_name="Bro"
last_name="Code"
full_name=first_name + last_name
print("Hello "+ full_name)age = 21
# to increment
age +=1
print(age)
print('Your age is: '+str(age))when assigning value for integer type variables we do not use quotes as strings are not used in math.
height=250.5
print(height)can only store True or False values
human = False
print(human)- use the 'type' function to find variable data type
print(type(name))
print(type(age))
print(type(height))
print(type(human))- multiple assignment allows us to assign multiple variables at the same time in one line of code.
name, age, attractive= "Bro", 32, True
print(name, age, attractive)in case different variables hold same value
Bill = Tina = Steve = 30
print(Bill)- some functions we can use with strings
print(name.find("B"))
print(name.capitalize())
print(name.upper())
print(name.lower())
print(name.isdigit())
print(name.isalpha())
print(name.count("o"))
print(name.replace("o", 'a'))
print(name*3)- type casting is converting the data type of a value to another data type.
x = 1 #int
y = 2.0 #float
z = "3" #str
# convert to string
x = str(x)
y = str(y)
z = str(z)
# convert to float
x = float(x)
y = float(y)
z = float(z)
# convert to integer
x = int(x)
y = int(y)
z = int(z)name = input("What is your name?: ")
age = int(input("How old are you?: "))
height = float(input("How tall are you?: "))
print("Hello "+name)
print("You are "+str(age)+ " years old")
print("You are "+str(height)+ " cm tall")we've converted the age into integer data type when entering it but we had to convert it back to string to display it
import math
pi = 3.14
x = 1
y = 2
z = 3
print(round(pi))
print(math.ceil(pi))
print(math.floor(pi))
print(abs(pi)) # absolute value
print(pow(pi, 2)) # power function
print(math.sqrt(pi)) # square root
print(max(pi,x,y,z)) # finds max value
print(min(pi,x,y,z)) # finds min value- string slicing is creating a substring by extracting elements from another string. indexing[ ] or slice( )
# [start:stop:step]
# start index in inclusive. stop index is exclusive.
# step is how much the index increases. default is 1.
name = "Bro Code"
first_name = name[:3]
last_name = name[4:]
funky_name = name[::3]
reversed_name = name[::-1]
print(first_name)
print(last_name)
print(funky_name)
website1 = 'http://test.com'
website2 = 'http://google.com'
slice = slice(7,-4)
print(website1[slice])
print(website2[slice])- a block of code that will execute if its condition is true.
age = int(input("How old are you?:"))
if age == 100:
print("You are a century old!")
elif age >= 18:
print("You are an adult!")
elif age <0:
print("You have not been born yet!")
else:
print("You are a child!")- the logical operators ( AND , OR , NOT ) are used to check if two or more conditional statements are true.
temp = int(input("What is the temperature ourside?: "))
if (temp >= 0 and temp <= 30):
print("The weather is good today!")
print("Go outside!")
elif (temp <0 or temp >30):
print("The weather is bad today!")
print("Stay inside!")
# the NOT operator inverts the statement
if not(temp >= 0 and temp <= 30):
print("The weather is bad today!")
print("Stay inside!")
elif not(temp <0 or temp >30):
print("The weather is good today!")
print("Go outside!")- a while loop is a statement that will execute its block of code as long as its condition is true
name = ""
while len(name) == 0: # we can also write "while not name:"
name = input("Enter your name: ")
print("Hello "+name)- a for loop is a statement that will execute its block of code a limited amount of times
for i in range(10):
print(i)- countdown timer
import time
for seconds in range(10,0,-1):
print(seconds)
time.sleep(1)
print("Happy New Year!")rows = int(input("How many rows?: "))
columns = int(input("How many columns?: "))
symbol = input("Enter a symbol to use: ")
for i in range(rows):
for j in range(columns):
print(symbol, end="") # to avoid making a new line
print()- used to change a loop's execution from its normal sequence
# break = used to terminate the loop entirely
# continue = skips to the next iteration of the loop
# pass = does nothing, acts as a placeholder
while True:
name = input("Enter your name: ")
if name !="":
break
phone_number = "123-456-7890"
for i in phone_number:
if i == "-":
continue
print(i, end="")
for i in range(1,21):
if i == 13:
pass
else: print(i)- lists are used to store multiple items in a single variable
food = ["pizza", "hamburger", "hotdog"]
food.append("ice cream")
food.remove("hotdog")
food.pop() #removes last element in list
food.insert(0,"cake")
food.sort()
food.clear()
print(food[0])
for x in food:
print(x)- a 2D list is basically a list of lists
drinks = ["coffee", "soda", "tea"]
dinner = ["pizza", "hamburger", "hotdog"]
desert = ["cake", "ice cream"]
food = [drinks, dinner, desert]
print(food[0][1])
print(food[1][1])- a tuple is a collection which is ordered and unchangeable, it's used to group together related data
student = ("Bro", 21, "male")
print(student.count("Bro"))
print(student.index("male"))
for x in student:
print(x)
if "Bro" in student:
print("Bro is here!")- a set is a collection which is unordered, unindexed and doesn't include duplicare values
utensils = {"fork", "spoon", "knife"}
dishes = {"bowl", "plate", "cup", "knife"}
utensils.add("napkin")
utensils.remove("fork")
utensils.clear()
dishes.update(utensils)
dinner_table = utensils.union(dishes)
print(dishes.difference(utensils))
print(utensils.intersection(dishes))
for x in dinner_table:
print(x)- a dictionary is a changeable, unordered collection of unique key:value pairs. dictionaries are fast because they use hashing, which allows us to access a value quickly!
capitals = {'USA':'Washington DC',
'India':'New Dehli',
'China': 'Beijing',
'Russia': 'Moscow'}
print(capitals['Russia']) #this causes issues if not in dictionary. Get method better.
print(capitals.get('Germany')) # this will return None if not there.
print(capitals.keys()) # will print only the keys
print(capitals.values()) # will print only the values
print(capitals.items()) # will print all items
for key, value in capitals.items(): # this will also print whole dictionary.
print(key, value)
capitals.update({'Germany': 'Berlin'}) # way to add to dictionary.
capitals.update({'USA': 'Las Vegas'}) # way to update or add to dictionary.
capitals.pop('China') # removes key, value from dictionary.
capitals.clear()- the index operator
[]gives us access to a sequence's element (ex. strings, lists, tuples..)
name = "bro Code!"
if(name[0].islower()):
name = name.capitalize()
print(name)
first_name = name[:3].upper()
last_name = name[4:].lower()
last_character = name[-1]
print(first_name)
print(last_name)
print(last_character)- a function is a block of code that is executed only when it is called
def hello(first_name, last_name, age): # parameters
print("Hello "+first_name+" "+last_name)
print("You are "+ str(age) + " years old") # we need to convert it to string
print("Have a nice day!")
hello("Bro", "Code", 21) # arguments- the return value is the value or object that a function sends back to the caller
def multiply(number1, number2):
return number1 * number2 # the result
x = multiply(6,8)
print(x)- arguments preceded by an identifier when passed to a function are known as keyword arguments; unlike positional arguments, their order does not matter, as python knows the names of the arguments that the function receives
def hello(first,middle,last):
print("Hello "+first+" "+middle+" "+last)
hello("Code", "Dude", "Bro") # positional arguments.
hello(last="Code", middle="Dude", first="Bro") # keyword arguments.- nested function calls are when one function call is used as an argument for another function. these calls are resolved from the innermost to the outermost, with the return value of the inner function serving as the argument for the next outer function
num = input("Enter a whole positive number: ")
print(num)
num = float(num)
print(num)
num = abs(num)
print(num)
num = round(num)
print(num)
# we can simplify all this using a nested function call
print(round(abs(float(input("Enter a whole positive number: ")))))- the region where a variable is recognized is called its scope. a variable is only available within the scope where it is created, and both global and local versions of a variable can be created
name = "Bro" # global scope (available inside & outside functions)
def display_name():
name = "Code" # local scope (available only inside this function)
print(name)
# LEGB Rule: Local -> Enclosing -> Global -> Built-in
display_name()
print(name)- *args is a parameter that will pack all arguments into a tuple, it is useful so that a function can accept a varying amount of arguments
def add(*stuff):
sum = 0
# stuff = list(stuff) # if you want to change an item in tuple, turn into list
#stuff[0] = 0 # this turns the 1st item to 0.
for i in stuff:
sum += i
return sum
print(add(1,2,3,4,5,6,7,8))- **kwargs is a parameter that will pack all arguments into a dictionary, it is useful so that a function can accept a varying amount of keyword arguments
def hello(**kwargs): # just need the two **, can name it anything
print("Hello "+ kwargs['first']+" "+kwargs['last'])
print("Hello",end=" ")
for key, value in kwargs.items():
print(value, end= " ") # end=" " replaces the new line character (default) with space.
hello(title="Mr.", first="Bro", middle="Dude", last="Code")- the
str.format()is an optional method that gives users more control when displaying outputs
animal = "cow"
item = "moon"
# print("The "+animal+" jumped over the "+item)
# a better way to write this would be using the str.format()
print("The {} jumped over the {}".format(animal, item))
print("The {0} jumped over the {1}".format(animal, item)) # positional argument
print("The {food} jumped over the {house}".format(house="tall", food="pizza")) # keyword argument
# another way to format
text = "The {} jumped over the {}"
print(text.format(animal, item))
name = "Bro"
print("Hello, my name is {:10}".format(name)) # adding ten spacing worth of padding after name
number = 3.14
print("The number pi is {:.3f}".format(number)) #adds 3 deciminal places.
print("The number is {:,}".format(number)) # adds commas
print("The number is {:b}".format(number)) # displays it in binary
print("The number is {:o}".format(number)) # displays it in octodecimal
print("The number is {:X}".format(number)) # displays it in hexidicimal.
print("The number is {:E}".format(number))import random
x = random.randint(1,6) # random integer between 1 and 6
y = random.random() # random floating point number
my_list = ['rock', 'paper', 'scissors']
z = random.choice(my_list)
cards = [1,2,3,4,5,6,7,8,9,'J','Q','K','A']
random.shuffle(cards)
print(cards)- exceptions are events detected during execution that interrupt the flow of a program
try:
numerator = int(input("Enter a number to divide: "))
denominator = int(input("Enter a number to divide by: "))
results = numerator / denominator
except ZeroDivisionError:
print("You cannot divide by zero! Idiot!")
except ValueError:
print("Enter only numbers please.")
except Exception:
# good pratice to put specific exceptions first.
print("Something went wrong :(")
else:
print(results)
finally: # should be at end as you want to close files when done
print("This will always execute")import os
path = "C:\\Users\\Cakow\\Desktop\\test.txt"
# need to manually put in double back slashes
if os.path.exists(path):
print("That location exists!")
if os.path.isfile(path):
print("That is a file")
elif os.path.isdir(path):
print("That is a directory")
else:
print("That location does not exist")try:
with open('test.txt') as file: # will need file path and double-slashes if the file isn't here
print(file.read()) #'with' will also close files after reading them!
except FileNotFoundError:
print("That file was not found")text = "Hello \nThis is some text \nHave a good date!\n"# \n is a new line.
with open('test.txt', 'w') as file: # by default the mode is r. but here it is set to w for write
# mode 'a' will append the new lines to the file
file.write(text)# copyfile() = copies contents of a file
# copy() = copyfile(0 + persmission mode + destination can be a directory
# copy2() = copy() + copies metadata (file's creation and modification times)
import shutil # good module to copy files
shutil.copyfile('test.txt', 'copy.txt') # this function has both a source and a destination
# if the file is not here, you would need to list the file pathimport os
source = "test.txt"
destination = "C:\\Users\\Cakow\\Desktop\\test.txt"
try: # recommended doing code in try/except block to handle issues!
if os.path.exists(destination):
print("There is already a file there")
else:
os.replace(source,destination)
print(source+" was moved")
except FileNotFoundError:
print(source+" was not found")import os
import shutil
path = 'test.txt'
try:
os.remove(path) # delete a file
# os.rmdir(path) # delete a file or empty folder
# shutil.rmtree(path) # delete directory and all files contained within
except FileNotFoundError:
print("That file was not found")
except PermissionError:
print("You do not have permission to delete that")
except OSError:
print("That folder contains files")
else:
print(path+" was deleted")- a module is a file containing python code; it can contain functions, classes.. modules are used with modular programming, which is used to separate a program into parts
in messages.py
def hello():
print("Hello! Have a nice day!")
def bye():
print("Bye! Have a wonderful time")in our main module
import messages # can import messages (hello,bye) OR messages * (all of it)
messages.hello()
messages.bye()