Python Practical Guide: File I/O, CSV, JSON, HTTP Requests, SQLite, Scheduling, Logging, Argument Parsing, Compression, Subprocess, DateTime, Email, Image Processing, NumPy, Pandas, Regex, System Info, Socket Programming, and AsyncIO

1. File read/write: with open('file.txt','r') as file: content = file.read() print(content) and with open('output.txt','w') as file: file.write("Hello, World!")

2. CSV handling: read with import csv with open('data.csv','r') as file: reader = csv.reader(file) for row in reader: print(row) ; write with import csv data = [['Name','Age'],['Alice',30],['Bob',25]] with open('output.csv','w', newline='') as file: writer = csv.writer(file) writer.writerows(data)

3. JSON handling: read with import json with open('data.json','r') as file: data = json.load(file) print(data) ; write with import json data = {'name':'Alice','age':30} with open('output.json','w') as file: json.dump(data, file)

4. HTTP requests: GET with import requests response = requests.get('https://api.example.com/data') if response.status_code == 200: print(response.json()) else: print(f"Request failed with status code: {response.status_code}") ; POST with import requests payload = {'key':'value'} response = requests.post('https://api.example.com/submit', data=payload) if response.status_code == 200: print(response.json()) else: print(f"Request failed with status code: {response.status_code}")

5. SQLite database: import sqlite3 conn = sqlite3.connect('example.db') c = conn.cursor() c.execute('''CREATE TABLE IF NOT EXISTS stocks (date text, trans text, symbol text, qty real, price real)''') c.execute("INSERT INTO stocks VALUES ('2023-01-01','BUY','RHAT',100,35.14)") conn.commit() c.execute('SELECT * FROM stocks') print(c.fetchall()) conn.close()

6. Scheduling tasks: import schedule, time def job(): print("I'm working...") schedule.every(10).seconds.do(job) while True: schedule.run_pending() time.sleep(1)

7. Logging: import logging logging.basicConfig(filename='app.log', level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s') logging.info('This is an info message') logging.warning('This is a warning message') logging.error('This is an error message')

8. Command‑line argument parsing: import argparse parser = argparse.ArgumentParser(description='Process some integers.') parser.add_argument('integers', metavar='N', type=int, nargs='+', help='an integer for the accumulator') parser.add_argument('--sum', dest='accumulate', action='store_const', const=sum, default=max, help='sum the integers (default: find the max)') args = parser.parse_args() print(args.accumulate(args.integers))

9. File compression: import zipfile with zipfile.ZipFile('archive.zip','w') as zipf: zipf.write('file.txt') ; extraction with import zipfile with zipfile.ZipFile('archive.zip','r') as zipf: zipf.extractall('.')

10. Subprocess execution: import subprocess result = subprocess.run(['ls','-l'], capture_output=True, text=True) print(result.stdout)

11. Date and time: from datetime import datetime now = datetime.now() print(now.strftime("%Y-%m-%d %H:%M:%S"))

12. Sending email: import smtplib from email.mime.text import MIMEText msg = MIMEText('This is the body of the email') msg['Subject'] = 'Hello' msg['From'] = '[email protected]' msg['To'] = '[email protected]' with smtplib.SMTP('smtp.example.com', 587) as server: server.starttls() server.login('username','password') server.sendmail('[email protected]',["[email protected]"],msg.as_string())

13. Image processing: from PIL import Image img = Image.open('image.jpg') img_resized = img.resize((800,600)) img_resized.save('resized_image.jpg')

14. Text replace: text = "Hello, World!" new_text = text.replace("World","Python") print(new_text)

15. Numerical computation with NumPy: import numpy as np arr = np.array([1,2,3,4]) print(arr * 2)

16. Data analysis with Pandas: import pandas as pd df = pd.DataFrame({ 'Name': ['Alice','Bob','Charlie'], 'Age': [25,30,35] }) print(df.describe())

17. Regular expressions: import re pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b' text = "Contact us at [email protected]" match = re.search(pattern, text) if match: print(match.group())

18. System information: import platform print(platform.system()) print(platform.release()) print(platform.version())

19. Simple TCP server: import socket host = '127.0.0.1' port = 65432 with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s: s.bind((host, port)) s.listen() conn, addr = s.accept() with conn: print('Connected by', addr) while True: data = conn.recv(1024) if not data: break conn.sendall(data)

20. Simple TCP client: import socket host = '127.0.0.1' port = 65432 with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s: s.connect((host, port)) s.sendall(b'Hello, Server!') data = s.recv(1024) print('Received', repr(data))

21. Asynchronous programming with asyncio: import asyncio async def my_coroutine(): print("Starting coroutine") await asyncio.sleep(1) print("Coroutine finished") async def main(): task = asyncio.create_task(my_coroutine()) await task asyncio.run(main())