Python Guide | Generated by AI
Here is a concise Python guide covering string operations, math, text processing, I/O, file handling, networking, collections, and multithreading. Each section includes a brief overview and practical examples to help you get started or refresh your knowledge.
Python Guide: Essential Topics
1. String Operations
Strings in Python are immutable sequences of characters. You can perform operations like concatenation, repetition, slicing, and use built-in methods for manipulation.
Examples:
# Concatenation and repetition
s1 = "Hello"
s2 = "World"
print(s1 + " " + s2) # Output: Hello World
print(s1 * 3) # Output: HelloHelloHello
# Slicing
print(s1[1:4]) # Output: ell
# Built-in methods
print(s1.upper()) # Output: HELLO
print(s2.lower()) # Output: world
print(" hi ".strip()) # Output: hi
print("a,b,c".split(',')) # Output: ['a', 'b', 'c']
print(','.join(['a', 'b', 'c'])) # Output: a,b,c
# String formatting with f-strings
name = "Alice"
age = 30
print(f"My name is {name} and I am {age} years old.") # Output: My name is Alice and I am 30 years old.
2. Math
The math module provides mathematical functions and constants for common calculations.
Example:
import math
print(math.sqrt(16)) # Output: 4.0
print(math.pow(2, 3)) # Output: 8.0
print(math.sin(math.pi / 2)) # Output: 1.0
print(math.pi) # Output: 3.141592653589793
3. Text Processing (Regular Expressions)
The re module enables pattern matching and text manipulation using regular expressions.
Example:
import re
text = "The rain in Spain"
match = re.search(r"rain", text)
if match:
print("Found:", match.group()) # Output: Found: rain
# Find all 4-letter words
print(re.findall(r"\b\w{4}\b", text)) # Output: ['rain', 'Spain']
4. I/O (Input and Output)
Basic input and output operations allow interaction with the user.
Example:
name = input("Enter your name: ")
print("Hello, " + name + "!")
5. File Handling
Python simplifies reading from and writing to files using the open() function, with the with statement recommended for automatic file closure.
Example:
# Writing to a file
with open("example.txt", "w") as f:
f.write("Hello, World!\n")
# Reading from a file
with open("example.txt", "r") as f:
content = f.read()
print(content) # Output: Hello, World!
6. Networking
The requests library (install with pip install requests) makes HTTP requests straightforward.
Example:
import requests
response = requests.get("https://api.github.com")
print(response.status_code) # Output: 200
print(response.json()) # Output: JSON data from GitHub API
7. Collections
The collections module offers specialized data structures like Counter, deque, namedtuple, etc. Here’s an example with Counter.
Example:
from collections import Counter
words = ["apple", "banana", "apple", "cherry"]
word_count = Counter(words)
print(word_count) # Output: Counter({'apple': 2, 'banana': 1, 'cherry': 1})
Other Collections:
namedtuple: Creates tuple subclasses with named fields.deque: Double-ended queue for efficient appends/pops from both ends.OrderedDict: Dictionary that remembers insertion order.defaultdict: Dictionary with a default value for missing keys.
8. Multithreading
The threading module enables concurrent task execution, ideal for I/O-bound operations.
Example:
import threading
import time
def print_numbers():
for i in range(5):
print(i)
time.sleep(1)
# Create and start a thread
t = threading.Thread(target=print_numbers)
t.start()
# Main thread continues
print("Main thread finished")
This guide provides a starting point for each topic with practical examples. For more in-depth learning, consult the official Python documentation or specialized resources. Happy coding!