Python Regex Tutorial

In this Python article we want to learn about Python Regex Tutorial, Python is powerful programming language and it is used in a lot of area including data analysis, web development and scientific computing. one of the best thing about Python is this that it supports regular expressions or regex, using Python regex we can manipulate text and search for specific patterns in our data.

What is regular expression ?

Regular expression is a sequence of characters that defines a search pattern. you can use this pattern to search for specific patterns of text in a larger body of text. Regular expressions are used in many programming languages including Python, and it is used to manipulate and analyze text.

In Python re module provides different supports for regular expressions. for using regular expressions in Python first we need to import re module:

import re

import re

Now let’s talk about the basic syntax of regular expression, basic regex syntax in Python is a literal match. this means that the regular expression will search for an exact match of the specific text. for example this regular expression code will match string geekscoders in any text.

pattern = "geekscoders"

1	pattern = "geekscoders"

For searching this pattern in our text string, we can use re.search() method:

import re
pattern = "geekscoders"
text = "Welcome to geekscoders"
match = re.search(pattern, text)
print(match)

import re

pattern = "geekscoders"

text = "Welcome to geekscoders"

match = re.search(pattern, text)

print(match)

this match object returned by re.search() contains information about the match, including starting and ending positions of the match in the text string.

If you run this will be the result

One of the most powerful features of regular expressions is character classes. character classes allows you to match a group of characters instead of a single character. for example this regular expression will match any digit in a text string.

pattern = "\d"

1	pattern = "\d"

This pattern will match any digit character between 0 and 9 in a text string. for matching multiple digits in a row, you can use quantifier syntax. for example this regular expression code will match any string of three digits in a text string.

pattern = "\d{3}"

1	pattern = "\d{3}"

Another powerful feature of regular expressions is groups and capturing. groups allows you to group parts of the regular expression together, and capturing allows you to extract specific parts of the matched text.

for creating group in a regular expression, you can use parentheses. for example this regular expression will match any string that starts with cat and ends with dog:

pattern = "(cat.*dog)"

1	pattern = "(cat.*dog)"

In this regular expression group (cat.*dog) matches any string that starts with cat and ends with dog. for extracting matched text from this group, you can use group() method of the match object

import re

pattern = "(cat.*dog)"


text = "I have a cat named Fluffy and a dog named Spike."
match = re.search(pattern, text)
if match:
    group = match.group(1)
    print(group)