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Python Cheatsheet

Essential Python syntax, built-in functions, and common operations

Useful Python Resources

Python Documentation

Official Python documentation with complete language reference

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Python Package Index (PyPI)

Repository of Python packages - find and install third-party libraries

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Real Python

In-depth Python tutorials and articles for all skill levels

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Python Cookbook

Solutions to common Python programming problems

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Basic Syntax

variable = value

Variable assignment

print(value)

Output a value to the console

# This is a comment

Single line comment

"""Multi-line comment"""

Multi-line comment/docstring

if condition: code

Basic if statement

for item in iterable: code

For loop syntax

while condition: code

While loop syntax

def function_name(params): return value

Function definition

Data Types

str("text")

String type

int(10)

Integer type

float(10.5)

Floating-point type

bool(True)

Boolean type

list([1, 2, 3])

List (mutable sequence)

tuple((1, 2, 3))

Tuple (immutable sequence)

dict({"key": "value"})

Dictionary (key-value pairs)

set({1, 2, 3})

Set (unique unordered elements)

String Operations

str.upper()

Convert string to uppercase

str.lower()

Convert string to lowercase

str.strip()

Remove whitespace from ends

str.split(delimiter)

Split string into list

",".join(list)

Join list elements with delimiter

str.replace(old, new)

Replace substring in string

str.format()

Format string with placeholders

f"Value: {variable}"

F-string formatting (Python 3.6+)

List Operations

list.append(item)

Add item to end of list

list.extend(iterable)

Add items from iterable to list

list.insert(index, item)

Insert item at position

list.remove(item)

Remove first occurrence of item

list.pop([index])

Remove and return item at index

list.sort()

Sort list in place

list.reverse()

Reverse list in place

list.copy()

Create shallow copy of list

Dictionary Operations

dict.get(key, default)

Get value with optional default

dict.keys()

Get view of dictionary keys

dict.values()

Get view of dictionary values

dict.items()

Get view of dictionary key-value pairs

dict.update(other_dict)

Update dictionary with elements from another

dict.pop(key[, default])

Remove specified key and return value

dict.clear()

Remove all items

dict.copy()

Create shallow copy of dictionary

File Operations

with open(file, "r") as f:

Open file for reading

with open(file, "w") as f:

Open file for writing

f.read()

Read entire file

f.readline()

Read single line from file

f.readlines()

Read all lines into list

f.write(string)

Write string to file

f.writelines(list)

Write list of strings to file

import json

Import JSON module

Object-Oriented Programming

class ClassName: pass

Define a class

class Child(Parent):

Class inheritance

def __init__(self):

Constructor method

@classmethod

Class method decorator

@staticmethod

Static method decorator

@property

Property decorator

super().__init__()

Call parent class method

isinstance(obj, class)

Check instance type

Exception Handling

try: code except Error: handle

Basic exception handling

raise Exception("message")

Raise an exception

finally:

Code that always executes

else:

Code that runs if no exception

except (Error1, Error2):

Catch multiple exceptions

except Error as e:

Catch and use error object

assert condition, message

Assertion statement

with context_manager:

Context manager protocol

Modules and Packages

import module

Import a module

from module import name

Import specific name

from module import *

Import all names (not recommended)

import module as alias

Import with alias

from . import module

Relative import

pip install package

Install package with pip

pip list

List installed packages

pip freeze > requirements.txt

Save dependencies list