5. Data Work · lesson 14 of 17 · 1 min · January 1, 2024

Regular Expressions

Searching text with pattern matching.

Regular expressions provide a way of searching text. They are incredibly useful but also fairly complicated, so much so that there are entire books written about them.

We will explain their details the few times we encounter them; here are a few examples of how to use them in Python:

regex.py

import re

print all([                                 # all of these are true, because
  not re.match("a", "cat"),               # * 'cat' doesn't start with 'a'
  re.search("a", "cat"),                  # * 'cat' has an 'a' in it
  not re.search("c", "dog"),              # * 'dog' doesn't have a 'c' in it
  3 == len(re.split("[ab]", "carbs")),    # * split on a or b to ['c','r','s']
  "R-D-" == re.sub("[0-9]", "-", "R2D2")  # * replace digits with dashes
]) # prints True