Python Cheat Sheet¶
Beginner Concepts¶
Variables and Data Types¶
# Variables and Data Types
name = "John" # String
age = 25 # Integer
height = 1.75 # Float
is_student = True # Boolean
# Basic Input and Output
print("Hello, World!")
name = input("Enter your name: ")
print("Hello,", name)
# Conditional Statements
if age >= 18:
print("You are an adult")
else:
print("You are a minor")
# Conditional Statements
if age >= 18:
print("You are an adult")
else:
print("You are a minor")
# Loops
for i in range(5):
print(i)
while condition:
# Code block
# Lists
numbers = [1, 2, 3, 4, 5]
fruits = ["apple", "banana", "orange"]
# Functions
def greet(name):
print("Hello,", name)
greet("Alice")
# Dictionaries
person = {"name": "John", "age": 25, "city": "New York"}
print(person["name"])
Intermediate concepts¶
# Dictionaries
person = {"name": "John", "age": 25, "city": "New York"}
print(person["name"])
# List Comprehensions
squared_numbers = [x**2 for x in range(1, 6)]
print(squared_numbers)
# Classes and Objects
class Car:
def __init__(self, make, model):
self.make = make
self.model = model
my_car = Car("Toyota", "Corolla")
print(my_car.make, my_car.model)
# Exception Handling
try:
result = 10 / 0
except ZeroDivisionError:
print("Error: Division by zero")
# Modules and Packages
import math
print(math.sqrt(16))
# File Handling
with open("data.txt", "r") as file:
data = file.read()
print(data)
Virtual Environments¶
Why Use Virtual Environments?
- Isolation: Each virtual environment is self-contained, with its own Python interpreter and packages, preventing conflicts between different projects.
- Dependency Management: Allows you to specify project-specific dependencies without affecting other projects.
- Portability: Virtual environments can be easily shared or recreated, ensuring consistent environments across different systems.
# Create - This command creates a new directory named myenv containing the virtual environment.
python -m venv myenv
# Activate
source myenv/bin/activate
# Within the virtual emvironment, any Python package can be installed using 'pip' and will be specific to that environment.
pip install package_name
# Deactivate:
deactivate