This cheat sheet covers some of the most commonly used Python commands, functions, and syntax to help you work efficiently with Python code.
Use this cheat sheet to jumpstart your Python learning journey.
1. Python Basics
1.1. Print and Input
print() – Output to the console.
print() – Output to the console.
print("Hello, world!")input() – Get user input.
name = input("Enter your name: ") # Takes user input1.2. Variables and Data Types
String – Text data.
String – Text data.
myString = "Hello, Python!"Integer – Whole number.
myInt = 42Float – Decimal number.
myFloat = 3.14Boolean – True or False value.
isActive = True1.3. Comments
Single-line comment:
Single-line comment:
# This is a commentMulti-line comment (using triple quotes):
'''This is a
multi-line comment''' 2. Data Structures
2.1. Lists
Create a list:
Create a list:
myList = [1, 2, 3, 4, 5]Access list items:
print(myList[0]) # Access first element (index 0)Add an item:
myList.append(6) # Add 6 to the listRemove an item:
myList.remove(3) # Remove the first occurrence of 3Slice a list:
subList = myList[1:4] # Get items from index 1 to 32.2. Tuples
Create a tuple:
Create a tuple:
myTuple = (1, 2, 3)Access tuple items:
print(myTuple[0]) # Access first itemTuples are immutable – Cannot change values once created.
2.3. Dictionaries
Create a dictionary:
Create a dictionary:
myDict = {"name": "John", "age": 25}Access dictionary items:
print(myDict["name"]) # Access value for 'name'Add or update a key-value pair:
myDict["city"] = "New York"Delete a key-value pair:
del myDict["age"]2.4. Sets
Create a set:
Create a set:
mySet = {1, 2, 3, 4}Add an item:
mySet.add(5)Remove an item:
mySet.remove(3) 3. Conditionals and Loops
3.1. If, Elif, Else
If statements:
If statements:
if x > 10:
print("x is greater than 10")Elif and Else:
if x > 10:
print("x is greater than 10")
elif x == 10:
print("x is equal to 10")
else:
print("x is less than 10")3.2. For Loop
Iterate over a range:
Iterate over a range:
for i in range(5): # From 0 to 4
print(i)Iterate over a list:
myList = ["apple", "banana", "cherry"]
for fruit in myList:
print(fruit)3.3. While Loop
While loop example:
While loop example:
count = 0
while count < 5:
print(count)
count += 13.4. Break, Continue, and Pass
break – Exit the loop.
break – Exit the loop.
for i in range(5):
if i == 3:
break
print(i)continue – Skip the current iteration.
for i in range(5):
if i == 3:
continue
print(i)pass – Do nothing, used as a placeholder.
for i in range(5):
if i == 3:
pass # Do nothing
print(i) 4. Functions
4.1. Define a Function
Basic function definition:
Basic function definition:
def greet(name):
print("Hello, " + name)Function with return value:
def add(a, b):
return a + b4.2. Lambda Functions
Lambda function (anonymous function):
Lambda function (anonymous function):
add = lambda a, b: a + b
print(add(2, 3)) # Output: 54.3. Default Argument Values
Function with default argument:
Function with default argument:
def greet(name="Guest"):
print("Hello, " + name)
greet() # Output: Hello, Guest
greet("Alice") # Output: Hello, Alice 5. Exception Handling
5.1. Try, Except
Basic exception handling:
Basic exception handling:
try:
x = 10 / 0
except ZeroDivisionError:
print("Cannot divide by zero!")Handling multiple exceptions:
try:
x = int("abc")
except ValueError:
print("Invalid input!")
except ZeroDivisionError:
print("Cannot divide by zero!")Finally – Code that always runs:
try:
file = open("myfile.txt", "r")
except FileNotFoundError:
print("File not found!")
finally:
print("This will always execute.") 6. File I/O
6.1. Open, Read, and Write Files
Open a file:
Open a file:
file = open("file.txt", "r") # "r" = read modeRead contents:
content = file.read() # Read entire file
print(content)
file.close() # Always close the file when doneWrite to a file:
with open("file.txt", "w") as file: # "w" = write mode
file.write("Hello, world!")Reading lines from a file:
with open("file.txt", "r") as file:
for line in file:
print(line.strip()) # Strip newline characters 7. Classes and Objects
7.1. Define a Class
Creating a class:
Creating a class:
class Dog:
def __init__(self, name, breed):
self.name = name
self.breed = breed
def bark(self):
print(self.name + " says Woof!")Create an object:
myDog = Dog("Rex", "German Shepherd")
myDog.bark() # Output: Rex says Woof!7.2. Inheritance
Inheritance in classes:
Inheritance in classes:
class Animal:
def speak(self):
print("Animal speaks")
class Dog(Animal):
def speak(self):
print("Dog barks")
dog = Dog()
dog.speak() # Output: Dog barks
8. Useful Built-in Functions
8.1. len()
Get length of a list, string, etc.:
myList = [1, 2, 3]
print(len(myList)) # Output: 3
8.2. range()
Generate a range of numbers:
for i in range(5): # Loop from 0 to 4
print(i)
8.3. sorted()
Sort a list:
myList = [3, 1, 4, 1, 5, 9]
print(sorted(myList)) # Output: [1, 1, 3, 4, 5, 9]
8. Useful Built-in Functions
8.1. len()
Get length of a list, string, etc.:
Get length of a list, string, etc.:
myList = [1, 2, 3]
print(len(myList)) # Output: 38.2. range()
Generate a range of numbers:
Generate a range of numbers:
for i in range(5): # Loop from 0 to 4
print(i)8.3. sorted()
Sort a list:
Sort a list:
myList = [3, 1, 4, 1, 5, 9]
print(sorted(myList)) # Output: [1, 1, 3, 4, 5, 9]8.4. sum()
Get the sum of a list:
Get the sum of a list:
numbers = [1, 2, 3, 4]
print(sum(numbers)) # Output: 108.5. min() and max()
Find minimum and maximum values:
Find minimum and maximum values:
numbers = [3, 1, 4, 1, 5, 9]
print(min(numbers)) # Output: 1
print(max(numbers)) # Output: 9This cheat sheet provides the essential Python concepts, syntax, and functions to help you write clean, efficient Python code.
Happy Codding ;)
