Python Cheat Sheet - Every Syntax Pattern You Need (2026)

Python Cheat Sheet (2026)

Every Python syntax pattern in one page. Keep this handy.

Data Types

str = "hello"                # String
num = 42                      # Integer
float_num = 3.14              # Float
bool_val = True               # Boolean
my_list = [1, 2, 3]           # List (mutable)
my_tuple = (1, 2, 3)          # Tuple (immutable)
my_dict = {"key": "value"}   # Dictionary
my_set = {1, 2, 3}            # Set (unique)

List Comprehensions

squares = [x**2 for x in range(10)]
evens = [x for x in range(20) if x % 2 == 0]
flat = [item for sublist in nested for item in sublist]
# Dict comprehension
squares_dict = {x: x**2 for x in range(5)}

Functions

def greet(name: str, greeting: str = "Hello") -> str:
    return f"{greeting}, {name}!"

# Lambda
square = lambda x: x ** 2

# *args and **kwargs
def flexible(*args, **kwargs):
    print(args)    # tuple
    print(kwargs)  # dict

Classes

class User:
    def __init__(self, name: str, email: str):
        self.name = name
        self.email = email

    @property
    def display_name(self) -> str:
        return self.name.title()

    def __repr__(self) -> str:
        return f"User({self.name})"

# Inheritance
class Admin(User):
    def __init__(self, name, email, permissions):
        super().__init__(name, email)
        self.permissions = permissions

File I/O

# Read file
with open("file.txt") as f:
    content = f.read()
    lines = f.readlines()

# Write file
with open("output.txt", "w") as f:
    f.write("Hello world")

# JSON
import json
data = json.loads(json_string)
json_string = json.dumps(data, indent=2)

Error Handling

try:
    result = risky_operation()
except ValueError as e:
    print(f"Value error: {e}")
except Exception as e:
    print(f"Error: {e}")
finally:
    cleanup()

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