Capturing

Lesson 17 of 28 in Coddy's RegEx in Python course.

Capturing groups not only group parts of a pattern but also capture the matched text. These captured groups can be referenced later in the pattern or used in the replacement string in substitution.

import re

text = "abab abab abab"
pattern = r"(ab)\1"
matches = re.findall(pattern, text)

print(matches)  # Output: ['ab', 'ab']

In the above example, the pattern (ab)\1 captures the group "ab" and then looks for the same group immediately after it. The \1 is a backreference to the first captured group.

Another example:

import re

text = "My email is example@example.com and my backup is backup@example.com."
pattern = r"(\w+)@example\.com"
matches = re.findall(pattern, text)

print(matches)  # Output: ['example', 'backup']

In the above example, the pattern (\w+)@example\.com captures the part of the email address before @example.com.

Challenge

Easy

Write a function named find_repeated_patterns that takes a text string as input and returns a list of repeated patterns of two characters.

Try it yourself

import re

def find_repeated_patterns(text):
    # Write code here

All lessons in RegEx in Python

1Introduction

Introduction

4Anchors and Quantifiers

Anchors Boundaries Quantifiers Repetitions

7Final Challenges

Extracting Hashtags Finding Email Addresses Valid Phone Numbers Finding Dates Capitalized Words

2re Library

findall search split sub

5Grouping and Advanced Patterns

GroupingCapturingPipe Operator Alternation Lookaheads Lookbehinds

3Basic Pattern Syntax

Basic Metacharacters Literals Character Classes Ranges Common Predefined Classes Advanced Predefined Classes

6Advanced Techniques

Escape Metacharacters Escape Sequences