Python Cheatsheet

name = 'John'
age = 30
is_student = False
height = None

# Complex data types
numbers = [1, 2, 3]

person = { 'name': 'John', 'age': 30 }

set_items = {1, 2, 3}

tuple_items = (1, 2, 3)

if age > 18:
  print('Adult')
else:
  print('Minor')

# Loops
for i in range(5):
  print(i)

i = 0
while i < 5:
  print(i)
  i += 1

# Ternary operator
message = 'Adult' if age > 18 else 'Minor'

def greet(name):
  return f'Hello, {name}'

print(greet('John'))

# Lambda expression
add = lambda x, y: x + y
print(add(5, 10))

# Keyword arguments and default parameters
def greet(name='Guest', age=18):
  return f'Hello, {name}. You are {age}.'

class Animal:
  def __init__(self, name):
    self.name = name
  def speak(self):
    print(f'{self.name} makes a sound.')

class Dog(Animal):
  def bark(self):
    print(f'{self.name} barks.')

rex = Dog('Rex')
rex.speak()
rex.bark()

# Inheritance
class Cat(Animal):
  def meow(self):
    print(f'{self.name} meows.')

whiskers = Cat('Whiskers')
whiskers.speak()
whiskers.meow()

# Class methods and static methods
class MathUtils:
  @classmethod
  def add(cls, a, b):
    return a + b

  @staticmethod
  def subtract(a, b):
    return a - b

try:
  result = 10 / 0
except ZeroDivisionError as e:
  print(f'Error: {e}')
else:
  print('No error')
finally:
  print('This will always run')

# List comprehension
squares = [x**2 for x in range(10) if x % 2 == 0]
print(squares)

# Generator expression
gen = (x**2 for x in range(10) if x % 2 == 0)
for value in gen:
  print(value)

with open('file.txt', 'r') as file:
  content = file.read()
  print(content)

with open('output.txt', 'w') as file:
  file.write('Hello, World!')

# Appending to a file
with open('output.txt', 'a') as file:
  file.write('\nAppending text')

def decorator(func):
  def wrapper(*args, **kwargs):
    print('Before function call')
    result = func(*args, **kwargs)
    print('After function call')
    return result
  return wrapper

@decorator
def say_hello(name):
  print(f'Hello, {name}')

say_hello('John')

# Iterator class
class MyIterator:
  def __init__(self, start, end):
    self.current = start
    self.end = end

  def __iter__(self):
    return self

  def __next__(self):
    if self.current < self.end:
      self.current += 1
      return self.current - 1
    else:
      raise StopIteration

for i in MyIterator(1, 5):
  print(i)

# Generator function
def countdown(num):
  while num > 0:
    yield num
    num -= 1

for count in countdown(5):
  print(count)

import asyncio

async def fetch_data():
  await asyncio.sleep(1)
  print('Data fetched after 1 second')

asyncio.run(fetch_data())

# Running multiple coroutines
async def main():
  await asyncio.gather(fetch_data(), fetch_data())

asyncio.run(main())

person = { 'name': 'John', 'age': 30 }

print(person['name'])

person['age'] = 31

for key, value in person.items():
  print(f'{key}: {value}')

# Dictionary comprehension
squared_numbers = {x: x**2 for x in range(5)}
print(squared_numbers)

import math
result = math.sqrt(16)
print(result)  # 4.0

import os
print(os.getcwd())

# Importing from custom modules
from my_module import my_function
my_function()

class CustomContext:
  def __enter__(self):
    print('Entering context')
  def __exit__(self, exc_type, exc_value, traceback):
    print('Exiting context')

with CustomContext():
  print('Inside context')

import re
pattern = r'\d+'
result = re.findall(pattern, 'The number is 123')
print(result)  # ['123']

# Using re.match and re.search
if re.match(r'\d+', '123abc'):
  print('Match found')

import json
data = { 'name': 'John', 'age': 30 }
json_data = json.dumps(data)
parsed_data = json.loads(json_data)
print(parsed_data['name'])  # 'John'

import datetime

now = datetime.datetime.now()
print(now)

formatted_date = now.strftime('%Y-%m-%d %H:%M:%S')
print(formatted_date)

# Time delta
delta = datetime.timedelta(days=7)
next_week = now + delta
print(next_week)

import unittest

class TestMathOperations(unittest.TestCase):
  def test_add(self):
    self.assertEqual(1 + 1, 2)

if __name__ == '__main__':
  unittest.main()

import threading

def print_numbers():
  for i in range(5):
    print(i)

thread = threading.Thread(target=print_numbers)
thread.start()

import multiprocessing

process = multiprocessing.Process(target=print_numbers)
process.start()
process.join()