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PYTHON | QUICK REFERENCE

This section gives a quick reference to popular Python commands

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SECTION 1 | BASIC SYNTAX

ELEMENT	DESCRIPTION
Variables	Variables are containers for storing data values. Remember the rules for creating variables. VARIABLE NAMING RULES ✘ Cannot start the name with a number ​✘ Cannot contain spaces ​✘ Cannot use command words such as print, python, turtle, exit, for, while and many more... VARIABLE NAMING CONVENTIONS ✓Should start with a lowercase letter ✓If more than one word used the first letter uppercase of proceeding words or use _ to join words ​✓Names should be meaningful to the content of the variable​ firstName = "John" age = 25
​input()	The input() function allows you to prompt the user for input. ​user_name = input("Enter your name: ")
​Single Line Comments	Used to add comments to your code that Python will ignore during execution. ​# This is a single-line comment
Multi Line Comments	Python does not have a specific syntax for multi-line comments, but you can use triple quotes. ''' This is a multi-line comment. Python will ignore this during execution. '''
print()	The print() function outputs text or variables to the console. ​print("Hello, World!")
Strings	​ Strings are sequences of characters, enclosed in either single or double quotes. greeting = ("Hello")
Concatenate with +	Concatenate strings and variables using the + sign joins them together as one value. message = ("Hello " + name)
Concatenate with ,	Using a comma in the print() function to join strings and variables. print("Hello", name)​
Concatenate with f{}	Using the f method to ​format strings allow you to embed expressions inside string literals. ​message = (f"My name is {name} and I am {age} years old.")

SECTION 2 | DATA TYPES

ELEMENT	DESCRIPTION
string	Strings are sequences of characters, enclosed in either single or double quotes. greeting = ("Hello") age = ("10") #Remember if you put a number in speech-marks Python will treat it as a string/text
integer - int	int - ​this is a integer number (no decimal places) ​num = (10)
float	​float - the is a number with decimal places ​num = (10.55)
boolean	Boolean represents one of two values: True or False. ​ is_student = True has_graduated = False

SECTION 3 | OPERATORS

​ARITHMETIC OPERATORS

COMPARISON OPERATORS

ASSIGNING OPERATORS

LOGIC OPERATORS

SECTION 4 | IF STATEMENTS

ELEMENT	DESCRIPTION	EXAMPLE
if	Used to perform different actions based on different conditions. if: Executes a block of code if the specified condition is true.	​if age > 18:     print("You are an adult.")
elif	​Executes a block of code if the previous conditions were not true, but the current condition is true.	if age < 13:     print("You are a child.") elif age < 18:     print("You are a teenager.")
else	​ Executes a block of code if no conditions are true.	​if age < 18:     print("You are not an adult.") else:     print("You are an adult.")
indentation	In Python, indentation is used to define code blocks. Unlike many other programming languages that use braces {} or other symbols to define code blocks, Python uses whitespace (tabs). Purpose: Indentation allows Python to determine which statements belong to a particular code block, such as those inside a loop or a conditional statement. This makes the code more readable and enforces a consistent structure.	age = int(input("how old are you: ")) ​​if age > 18:     print("You are an adult.") ​name = input("What is your name") #In this example only the print statement is inside the if statement

SECTION 5 | LOOPS

ELEMENT	DESCRIPTION	EXAMPLE
for value in	Iterates over a sequence (like a list, tuple, or string) and executes a block of code for each item in the sequence.	​for fruit in ["apple", "banana"]:     print(fruit)
for num in range	​The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (also by default), and stops before a specified number.	for num in range(5):     print(num)  # Outputs: 0, 1, 2, 3, 4
​Specifying Start and Stop	Generates a sequence of numbers starting from the first specified number up to (but not including) the second specified number.	for i in range(2, 5):     print(i)  # Outputs: 2, 3, 4
Specifying Step	Adds a third argument to specify the increment.	​for i in range(0, 10, 2):     print(i)  # Outputs: 0, 2, 4, 6, 8
while	​Executes a block of code as long as the specified condition is true.	​count = 0 while count < 5:     print(count)     count += 1
break	Used to change the behavior of loops during their execution. break: Exits the loop and continues executing the code after the loop.	for number in range(10):     if number == 5:         break     print(number)
continue	Skips the current iteration of the loop and continues with the next iteration.	​for number in range(5):     if number == 2:         continue     print(number)
pass	A null operation; nothing happens when it's executed. It's used as a placeholder.	​for letter in "Python":     if letter == "h":         pass     print(letter)

SECTION 6 | ARRAYS

	DESCRIPTION	EXAMPLE
append()	Adds an element to the end of the list.​	​fruits = ["apple", "banana"] fruits.append("cherry") print(fruits)  ​# Outputs: ['apple', 'banana', 'cherry']
remove()	Removes the first occurrence of the specified value from the list.	​fruits = ["apple", "banana", "cherry"] fruits.remove("banana") print(fruits)  # Outputs: ['apple', 'cherry']
​pop()	Removes the element at the specified position, or the last element if no index is specified.	​fruits = ["apple", "banana", "cherry"] fruits.pop(1) print(fruits)  # Outputs: ['apple', 'cherry']
​extend()	​Adds elements from another list (or any iterable) to the end of the current list.	fruits = ["apple", "banana"] fruits.extend(["cherry", "date"]) print(fruits)  ​# Outputs: ['apple', 'banana', 'cherry', 'date']
​count()	​Returns the number of times the specified value appears in the list.	​numbers = [1, 2, 3, 2, 4, 2] count = numbers.count(2) print(count)  # Outputs: 3
​index()	Returns the index of the first occurrence of the specified value.	​fruits = ["apple", "banana", "cherry"] idx = fruits.index("banana") print(idx)  # Outputs: 1
​sort()	​Sorts the list in ascending order by default.	​numbers = [3, 1, 4, 2] numbers.sort() print(numbers)  # Outputs: [1, 2, 3, 4]
​reverse()	​Reverses the order of the list.	fruits = ["apple", "banana", "cherry"] fruits.reverse() print(fruits)  ​# Outputs: ['cherry', 'banana', 'apple']
copy()	​Returns a copy of the list.	​newList = myList.copy()
clear()	​Removes all the elements from the list	listName.clear()
​set()	​Remove duplicates from a list	​myList2 = set(myList1)

SECTION 7 | 2D ARRAYS

ELEMENT	DESCRIPTION	EXAMPLE
Accessing Elements	Access elements using row and column indices.	​matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] print(matrix[1][2])  # Outputs: 6
​Appending Rows	​Add a new row to the 2D list.	matrix = [[1, 2, 3], [4, 5, 6]] matrix.append([7, 8, 9]) print(matrix)  ​# Outputs: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
​Appending Columns	​Add a new column to the 2D list.	matrix = [[1, 2], [4, 5], [7, 8]] for row in matrix:     row.append(0) # Appending 0 to each row print(matrix)  # Outputs: [[1, 2, 0], [4, 5, 0], [7, 8, 0]]
​Removing Rows	​Remove a row from the 2D list.	matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] matrix.pop(1) print(matrix)  ​# Outputs: [[1, 2, 3], [7, 8, 9]]
​Flattening a 2D List	​Convert a 2D list into a 1D list.	matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] flattened = [num for row in matrix for num in row] print(flattened)  ​# Outputs: [1, 2, 3, 4, 5, 6, 7, 8, 9]

SECTION 8 | FUNCTIONS

ELEMENT	DESCRIPTION	EXAMPLE
Defining Functions	​Functions are blocks of reusable code. They are defined using the def keyword.	​def greet(name):     return f"Hello, {name}!" print(greet("Alice"))  # Outputs: Hello, Alice!
​Positional Arguments	​Functions can take arguments (inputs) and return values (outputs). Positional Arguments: Arguments passed in order.	​def add(x, y):     return x + y
Keyword Arguments	Keyword Arguments are ​Arguments passed by name.	​def print_info(name, age):     print(f"Name: {name}, Age: {age}") print_info(age=30, name="John")
​Default Arguments	Default Arguments are Arguments with default values.	​def greet(name="Guest"):     return f"Hello, {name}!" print(greet())  # Outputs: Hello, Guest!
​Return Values	​Use the return keyword to send a result back	​def square(num):     return num * num result = square(4)  # result is 16
*args	​*args allows you to pass a variable number of positional arguments to a function. Inside the function, args is a tuple containing all passed arguments.	def add_numbers(*args):     return sum(args) print(add_numbers(1, 2, 3, 4))  # Outputs: 10
​*kwargs	**kwargs allows you to pass a variable number of keyword arguments to a function. Inside the function, kwargs is a dictionary containing all passed keyword arguments.	def print_data(**kwargs):     for key, value in kwargs.items():         print(f"{key}: {value}") print_data(name="John", age=30, country="USA") # Outputs: # name: John # age: 30 # country: USA