Python re Module

The re module lets you search, match, split, and replace text using regular expressions.

import re

Regular expressions are patterns for text. Use raw strings, such as r'\d+', so backslashes are passed to the regular expression engine correctly.

search()

search finds the first match anywhere in the string.

import re

match = re.search(r'\d+', 'Order #12345 shipped')
print(match.group())

findall returns all non-overlapping matches.

import re

emails = re.findall(r'[\w.-]+@[\w.-]+', 'a@example.com b@example.com')
print(emails)

['a@example.com', 'b@example.com']

sub replaces matching text.

import re

message = re.sub(r'\s+', ' ', 'too    many   spaces')
print(message)

too many spaces

Compiled patterns are useful when you reuse the same expression.

import re

pattern = re.compile(r'^python', re.IGNORECASE)
print(bool(pattern.match('Python Cheatsheet')))

True

Parentheses capture part of a match.

import re

match = re.search(r'(\w+)=(\d+)', 'count=42')
print(match.group(1))
print(match.group(2))

count
42

Always check whether a match exists before calling group().

import re

match = re.search(r'\d+', 'no number here')
if match:
    print(match.group())
else:
    print('No match')

No match