Python Regular Expressions — Pattern Matching Mastery

Python re Module

import re

text = 'Hello World 123'
print(re.findall(r'\d+', text))  # ['123']
print(re.findall(r'[a-zA-Z]+', text))  # ['Hello', 'World']

Common Patterns

# Email validation
email_pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
print(bool(re.match(email_pattern, 'user@example.com')))  # True

# Extract hashtags
hashtags = re.findall(r'#\w+', '#coding #python #webdev')

Groups and Named Groups

import re
date_pattern = r'(?P\d{4})-(?P\d{2})-(?P\d{2})'
match = re.search(date_pattern, '2026-07-15')
print(match.group('year'))   # 2026
print(match.group('month'))  # 07

Substitution

# Clean phone numbers
dirty = '(555) 123-4567'
clean = re.sub(r'[^\d]', '', dirty)
print(clean)  # 5551234567

# Slugify
def slugify(text):
    text = text.lower().strip()
    text = re.sub(r'[^\w\s-]', '', text)
    text = re.sub(r'[\s_-]+', '-', text)
    return text