Python RegEx with Examples

In this article, We are going to cover Python RegEx with Examples, Compile Method in Python, findall() Function in Python, The split() function in Python, The sub() function in python.

A Regular Expression is a sequence of characters that defines a search pattern.When we import re module, you can start using regular expressions.

Example of Python RegEx:

Search the string from start with and end with :

import re
a = "Regular Expression is a sequence of characters"
x = re.search("^Regular.*characters$", a)
if x:
  print("Match")
else:
  print("No match")

Output:

Match
Python RegEx with Examples 1

Compile Method in Python:

The purpose of the Compile Method is to compile the regex pattern which will be used for matching later. And Regular expressions are compiled into pattern objects, which have methods for various operations such as searching for pattern of string.

Example of Compile method in python:

import re 
# it will match string l to w  
p = re.compile('[l-w]') 
print(p.findall("Welcome to Python programming"))

Output:

['l', 'o', 'm', 't', 'o', 't', 'o', 'n', 'p', 'r', 'o', 'r', 'm', 'm', 'n']
Python RegEx with Examples 2

Another Example of compile method of python (numbers example):

import re 
# it will match numbers 0 to 9  
p = re.compile('[0-7]') 
print(p.findall("Welcome 21 to Python 4 programming 7 9"))

Output:

['2', '1', '4', '7']
Python RegEx with Examples 3

findall() Function in Python:

The findall() function returns a list of containing  all matches.

Example of findall() function in Python:

import re
text = "A sentence word is a single word that forms a full sentence"
x = re.findall("word", text)
print(x)

Output:

['word', 'word']
Python RegEx with Examples 4

If in this list no matches are found, an empty list is returned.

Example of findall() function in python:

import re
text = "A sentence word is a single word that forms a full sentence"
x = re.findall("to", text)
print(x)
if (x):
  print("Match")
else:
  print("No match")

Output:

[]
No match
Python RegEx with Examples 5

Example of findall() function in python:

import re 
text = "Hello my I'm 21 years old and my friend is 26 years old"
x = re.findall('\d+',text)			
print(x)	

Output:

['21', '26']
Python RegEx with Examples 6

The split() function in Python:

In python split() this is the most efficient and commonly used method to split on multiple characters at once.

Example of split() function in Python:

import re
text = "welcome to python programming"
x = re.split("\s", text)
print(x)

Output:

['welcome', 'to', 'python', 'programming']
Python RegEx with Examples 7

The sub() function in python:

This sub() function replaces the matches with the text of your choice.

Example of sub() function in Python:

import re
text = "Welcome to python programming"
x = re.sub("\s", "2", text)
print(x)

Output:

Welcome2to2python2programming
Python RegEx with Examples 8

Conclusion:

In this article We have covered Python RegEx with Examples, Compile Method in Python, findall() Function in Python, The split() function in Python, The sub() function in python.

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Reference:

Python Official Page

Shweta Mamidwar

I am Shweta Mamidwar working as a Intern in Product Company. Likes to share knowledge.

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