Python Regular Expressions With Example

Do you want to learn how to use regular expressions in Python? If so, you have come to the right place! In this blog post, we will discuss everything you need to know about Python regex.

We will cover the basics, such as what regular expressions are and how they work. Then, we will walk you through some common use cases for regular expressions in Python.

Finally, we will provide a few tips for debugging your regular expressions.

Let’s get started!

Contents

Python Regular Expressions

Regular expressions, also called regexes, are a powerful tool for matching patterns in strings. A regular expression is a special sequence of characters that defines a search pattern. Usually, such patterns are used by string-searching algorithms for “find” or “find and replace” operations on strings.

re module

In Python, you can use the re module to work with regular expressions. The re module provides several methods that allow you to search for and match patterns in strings. In addition, the re module provides several functions that let you perform other operations on regular expressions, such as compiling them or splitting them into subpatterns.

Now that we have covered the basics of regular expressions, let’s take a look at some common use cases for regular expressions in Python.

One common use case for regular expressions is to extract information from a string.

For example, let’s say you have the following string:

“John Doe, 123 Main Street, Chicago, IL 60601”

You could use a regular expression to extract the street address from this string.

The following regex would do the trick:


r'\d+\s+Main\s+Street'

This regex will match any sequence of one or more digits (the \d+ part) followed by one or more whitespace characters (the \s+ part), followed by the word “Main”, followed by another whitespace character, followed by the word “Street”.

Validate user input

Another common use case for regular expressions is to validate user input. For example, let’s say you have a form on your website that allows users to enter their email addresses.

You could use a regular expression to make sure that the email address is in the correct format. The following regex would do the trick:


r'\w+@\w+\.\w+'

This regex will match any sequence of one or more word characters (the \w+ part) followed by an @ sign, followed by another sequence of one or more word characters (the \w+ part), followed by a dot (the \. part), followed by another sequence of one or more word characters (the \w+ part).

re.match in python

if you want to re.match Here is a simple example that you can use to re.match.

import re

line = "Learn to Analyze Data with Scientific Python";

m = re.match( r'(.*) to (.*?) .*', line, re.M|re.I)

if m:
   print("m.group() : ", m.group())
   print("m.group(1) : ", m.group(1))
   print("m.group(2) : ", m.group(2))
else:
   print("No match!!")

Conclusion

We hope this blog post has been helpful in introducing you to the basics of using regular expressions in Python. If you have any questions, please feel free to leave a comment below. And be sure to check out our other blog posts for more tips and tricks on working with Python! Happy coding!