# Comments
# This is a comment
""" This is a
multi-line comment """
# Variables
name = "Alice"
age = 30
is_active = True
# Print
print(f"{name} is {age} years old")
---
📦 Data Types & Casting
# Primitives
str_var = "hello"
int_var = 42
float_var = 3.14
bool_var = False
none_var = None
# Type Casting
str(42), int("10"), float("3.5"), bool("")
# Check type
type(str_var)
---
🔁 Control Flow
# Conditional
if age > 18:
print("Adult")
elif age == 18:
print("Just 18")
else:
print("Minor")
# Loops
for i in range(5):
print(i)
while condition:
break # exit loop
continue # skip rest of this iteration
---
🧮 Operators
# Arithmetic
+, -, *, /, %, **, //
# Comparison
==, !=, <, >, <=, >=
# Logical
and, or, not
# Membership
in, not in
# Identity
is, is not
---
🔧 Functions
def greet(name: str = "Guest") -> str:
return f"Hello, {name}"
# Lambda
square = lambda x: x ** 2
---
🎒 Data Structures
List
nums = [1, 2, 3]
nums.append(4)
nums[0] # 1
nums[1:3] # slice
Tuple
coords = (4, 5)
x, y = coords
Set
items = {1, 2, 2, 3}
items.add(4)
Dictionary
person = {"name": "Alice", "age": 30}
person["name"]
person.get("age", 0)
---
🧱 Modules & Packages
import math
from datetime import datetime as dt
print(math.sqrt(9))
print(dt.now())
# Create module
touch utils.py
# Import from file
from utils import some_function
---
🗃️ File I/O
# Write
with open("file.txt", "w") as f:
f.write("Hello\n")
# Read
with open("file.txt", "r") as f:
content = f.read()
---
🧵 Error Handling
try:
result = 10 / 0
except ZeroDivisionError as e:
print("Error:", e)
finally:
print("Always runs")
---
🎭 Object-Oriented Programming (OOP)
class Person:
def __init__(self, name: str):
self.name = name
def greet(self):
return f"Hi, I'm {self.name}"
# Inheritance
class Student(Person):
def greet(self):
return super().greet() + " and I'm a student"
p = Person("Alice")
s = Student("Bob")
---
⏳ Comprehensions
# List
squares = [x ** 2 for x in range(10) if x % 2 == 0]
# Dictionary
d = {x: x ** 2 for x in range(5)}
# Set
unique = {x for x in [1, 2, 2, 3]}
---
⚙️ Lambda, Map, Filter, Reduce
# Lambda
multiply = lambda x, y: x * y
# Map
list(map(str.upper, ["a", "b", "c"]))
# Filter
list(filter(lambda x: x % 2 == 0, range(10)))
# Reduce
from functools import reduce
reduce(lambda x, y: x + y, [1, 2, 3])
---
📦 Virtual Environments
# Create
python -m venv venv
# Activate
source venv/bin/activate # Linux/macOS
venv\\Scripts\\activate # Windows
# Install packages
pip install -r requirements.txt
---
🧪 Testing
# test_sample.py
def add(a, b): return a + b
def test_add():
assert add(2, 3) == 5
# Run tests
pytest test_sample.py
---
🐞 Debugging
# Print-based
print("DEBUG:", variable)
# Built-in
import pdb; pdb.set_trace()
---
📚 Standard Libraries
Library Purpose
os Files, paths, env
sys CLI args, interpreter settings
math Math operations
datetime Time & date
json JSON encoding/decoding
random Randomness
logging Logging
re Regular expressions
---
🔗 Recommended Third-Party Libraries
Library Purpose
requests HTTP requests
pandas Data manipulation
flask Web apps
beautifulsoup4 HTML parsing
pytest Testing
fastapi Modern async web APIs
sqlalchemy ORM for SQL
numpy Scientific computing
---
👤 Author
Built by @
Licensed under MIT
Last Updated: August 2025
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