EDUCBA

EDUCBA

MENUMENU
  • Free Tutorials
  • Free Courses
  • Certification Courses
  • 600+ Courses All in One Bundle
  • Login

Python regex replace

Home » Software Development » Software Development Tutorials » Python Tutorial » Python regex replace

Python regex replace

Introduction to Python regex replace

In this article, we are discussing regular expression in Python with replacing concepts. In Python, strings can be replaced using replace() function, but when we want to replace some parts of string instead of entire string then we use regular expressions in Python which is mainly used for searching and replacing the patterns given with the strings that need to be replaced. In Python, regular expressions use the “re” module when there is a need to match or search or replace any part of a string with some specified pattern. So before searching or replacing any string we should know how to write regular expressions with known Meta characters that are used for writing patterns.

Functions of Python regex replace

In this article, we are discussing how regular expression is used for replacing string or substring. In Python, a common task is to find and replace a part of a string by some specified patterns using regular expressions so to do this we have to use sub() method. This is one of the most important methods in re module that uses regular expressions. In python, there are provided with meta characters to write regular expressions. Some of the metacharacters are given as below:

Start Your Free Software Development Course

Web development, programming languages, Software testing & others

1. + this symbol is used for matching one or more occurrences of preceding expressions.

2. ? this symbol is used for matching zero or one occurrence of preceding expressions.

3. . this is used to match any single character except a newline.

4. *  this symbol is used to match zero or more occurrences of preceding expressions

Popular Course in this category
Python Training Program (36 Courses, 13+ Projects)36 Online Courses | 13 Hands-on Projects | 189+ Hours | Verifiable Certificate of Completion | Lifetime Access
4.8 (8,353 ratings)
Course Price

View Course

Related Courses
Programming Languages Training (41 Courses, 13+ Projects, 4 Quizzes)Angular JS Training Program (9 Courses, 7 Projects)

5. ^ this is used to match the starting of the line.

6. $ this is used to match the end of the line.

This sub() method takes input as a pattern as substring to replace and substring to replace with and the original string that needs to be modified. Let us take a simple example below.

Example of Python regex replace

Below is an example  of Python regex replace:

Code:

import re
print("The simple program for sub() method for replacing:")
str = "Educba#!!Training#!!Institute"
print("The given string that needs to be replaced with given pattern is as follows:")
print(str)
res_str = re.sub("#!!"," ",str)
print("The string obtained after replacing special character with space is as follows:")
print (res_str)

Output:

Python regex replace Example 1

Explanation: In the above program, we can see that we have a simple string with some special characters in it. str =   Educba#!!Training#!!Institute this string needs to be modified with the string that should contain only the string and not special characters. So we need to replace special characters “#!!” with white space so that the given string is readable.

Now let us the proper syntax and example of the sub()method below.

Syntax:

re.sub( pattern, replc, string, max = 0)

Parameters of Python regex replace

Below are the parameters of Python regex replace:

  • pattern: In this, we write the pattern to be searched in the given string.
  • replc: This parameter is for replacing the part of the string that is specified.
  • string: This provides a string that needs to be replaced with a given pattern
  • max: This is used to replace all the occurrences until the max number is provided.

This sub() method is used to replace all the occurrence of the given “re” pattern in the string which is in replc parameter and substituting all occurrences unless the max value is specified and this method returns the modified string after the replacement of string is done.

Now let us see an example below that uses this sub() method:

Code:

import re
print("The below program is used to demonstrate sub() method:")
phonenum = "2004-959-559 # This is Phone Number"
print("The given string is as follows:")
print(phonenum)
correct_num1 = re.sub(r'#.*$', "", phonenum)
print("The correct phone number by removing special characters in the given string which means replacing them by space is as follows:")
print(correct_num1)
correct_num2 = re.sub(r'\D', "", phonenum)
print("Now we have replaced all the spaces and have only digits in the given string is as follows:")
print(correct_num2)

Output:

Python regex replace Example 2

Explanation: In the above program, we can see that we have a string with a variable name “phonenum” which we have a string with phone number also but we need only digits for obtaining proper phone number. So we have first obtained a phone number where we have specified a sub() method where we are replacing the string starting from “#” and everything till the end so we obtain the phone number as “2004-959-559”, but as we know there should not be any special characters in a phone number as it is a numerical value. Hence again we use sub () method which replaces the entire string to be only digits by using a regular expression as “\D” is replaced by nothing but it should contain only digits.

The sub() function uses backslash which has the same concept as in the regular expression for replacement of the text. Hence you should use raw string for replacing the string. Suppose let us consider if we want to c: \home as a replacement string then we specify the expression in the sub() method as r”c:\\home”.

Conclusion

In this article, we saw what is regular expression and why are they used when we want to replace any part of a string with a specified pattern. In Python, we use replace() function in string concept and it cannot be used for replacing the substring or part of string where replace() function is used to replace the entire string hence to do this we use regular expression which provides “re” module and to replace part of the string we use sub() function as we saw how simple it is to use this function for replacing the given pattern in the actual string to obtain the modified string. This is mainly used for replacing special characters with spaces or some other characters to make the string readable.

Recommended Articles

This is a guide to Python regex replace. Here we discuss a brief overview on the Python regex replace method and its Examples along with its Code Implementation. You can also go through our other suggested articles to learn more –

  1. Advantages of Programming in Python
  2. What is Recursive Function in Python?
  3. Introduction to Python Range Function
  4. Top 7 Methods of Python Set Function

Python Training Program (36 Courses, 13+ Projects)

36 Online Courses

13 Hands-on Projects

189+ Hours

Verifiable Certificate of Completion

Lifetime Access

Learn More

0 Shares
Share
Tweet
Share
Primary Sidebar
Python Tutorial
  • Function
    • Python Built-in Functions
    • Math Functions in Python
    • Python String Functions
    • Trigonometric Functions in Python
    • Python Input Function
    • Python Input String
    • Python String Operations
    • Python Stream
    • Python Multiline String
    • Python Regex
    • Python Regex Tester
    • Python regex replace
    • Python File Methods
    • Python Import CSV
    • Python Read CSV File
    • Python write CSV file
    • Python Delete File
    • Python File readline
    • Python if main
    • Python Main Method
    • List Method in Python
    • Python List Length
    • Recursive Function in Python
    • Copy List in Python
    • Python Range Function
    • Python Substring
    • Python list remove()
    • Python List Index
    • Python Set Function
    • Python len Function
    • Python eval()
    • Python Counter
    • ord Function in Python
    • strip Function in Python
    • Split Function in Python
    • Python Round Function
    • Python Map Function
    • Python String Join
    • Python format() Function
    • Python Contextlib
    • Python Compare Strings
    • Python Return Value
    • Python List count
    • Filter in Python
    • Python Slice String
    • Python Absolute Value
    • Python Trim String
    • Python Type Function
    • Lowercase in Python
    • Python xrange
    • Python yield
    • Python Find String
    • Max Function in Python
    • Python Power Function
    • pop() in Python
    • Python argparse
    • Python Pickle
    • Python Zip Function
    • Python Split String
    • super() in Python
    • Python Extend
    • Python String Replace
    • Python PEP8
    • Python Filter Function
    • Python if then else
    • Lambda in Python
    • Python BeautifulSoup
    • Python Sleep
    • Python Function Generator
    • Python @classmethod decorator
    • Python Endswith
    • Python BufferedReader
    • Python Async
    • Python Parser
    • Python SystemExit
    • Python pip
    • Python kwargs
  • Basics Part I
    • Introduction To Python
    • What Is Python
    • Careers in Python
    • Advantages of Python
    • Uses of Python
    • Python Features
    • Python Fast And python psyco
    • Python ImportError
    • Benefits and Limitations of Using Python
    • What can I do with?Python
    • Is Python a scripting language
    • Is Python Object Oriented
    • Is Python Open Source
    • Python Socket Programming
    • Useful Tips on Python Programming
    • Python You Should Be Using It
    • Python Web Development
    • Python Programming Beginners Tutorails
    • Practical Python Programming for Non-Engineers
    • Python Programming for the Absolute Beginner
    • Versions of?Python
  • Basic Part II
    • Comments in Python
    • Finally in Python
    • Python Multiline Comment
    • Python Data Types
    • Python Variables
    • Python Variable Types
    • Python Global Variable
    • Python Variable Scope
    • Python Private Variables
    • Python Default Arguments
    • Python Command-line Arguments
    • Indentation in Python
    • Object in Python
    • Python Keywords
    • Python Literals
    • Pointers in Python
    • Iterators in Python
    • Python User Input
    • Python Enumerate
    • Python Commands
    • Type Casting in Python
    • Python Identifiers
    • Python Constants
    • What is NumPy in Python?
    • Cheat Sheet Python
  • Frameworks
    • Python Frameworks
    • Python Compilers
    • Python Editors
    • Best Compiler for Python
    • Python IDE for Windows
    • Python IDE on Linux
  • Installation
    • How To Install Python
    • Install Python on Linux
    • Install Python on Windows
    • Install Anaconda Python
  • Operator
    • Python Operators
    • Arithmetic Operators in Python
    • Python Comparison Operators
    • Logical Operators in Python
    • Assignment Operators in Python
    • Unary Operators in Python
    • String Operators in Python
    • Boolean Operators in Python
    • Identity Operators in Python
    • Python Bitwise Operator
    • Python Remainder Operator
    • Python Modulus Operator
  • Control Statement
    • Conditional Statements in Python
    • Control Statements in Python
    • If Condition in Python
    • If Statement in Python
    • If Else Statement in Python
    • else if Statement in Python
    • Nested IF Statement in Python
    • Break Statement in Python
    • Python Switch Statement
  • Loops
    • Loops in Python
    • For Loop in Python
    • While Loop in Python
    • Do While Loop in Python
    • Python Nested Loops
    • Python Infinite Loop
    • Python Event Loop
  • Sorting
    • Sorting in Python
    • Sorting Algorithms in Python
    • Bubble Sort in Python
    • Merge Sort in Python
    • Heap Sort in Python
    • Quick Sort in Python
    • Python Sorted Function
  • Array
    • Arrays in Python
    • 2D Arrays In Python
    • 3d Arrays in Python
    • Multidimensional Array in Python
    • Python Array Functions
    • String Array in Python
    • Python Sort Array
    • Python Array Length
  • Inheritance
    • Inheritance in Python
    • Single Inheritance in Python
    • Multiple Inheritance in Python
    • Interface in Python
  • Exception
    • Python Exception Handling
    • Custom Exception in Python
    • Indentation Error in Python
    • Python IOError
    • Python EOFError
    • Python NotImplementedError
    • Python TypeError
    • Python ValueError
    • Python AssertionError
    • Python Unicode Error
    • Python NameError
    • Python StopIteration
    • Python OverflowError
    • Python KeyboardInterrupt
  • Advanced
    • Scope in Python
    • Python Collections
    • Constructor in Python
    • Destructor in Python
    • Python Overloading
    • Overriding in Python
    • Function Overloading in Python
    • Method Overloading in Python
    • Operator Overloading in Python
    • Method Overriding in Python
    • Encapsulation in Python
    • Static Method in Python
    • Assert in Python
    • Python References
    • Python Virtualenv
    • Python mkdir
    • Logistic Regression in Python
    • Dictionary in Python
    • Regular Expression in Python
    • Python Import Module
    • Python OS Module
    • Python Sys Module
    • Python Generators
    • Abstract Class in Python
    • Python File Operations
    • Sequences in Python
    • Stack in Python
    • Queue in Python
    • Tuples in Python
    • Python Magic Method
    • Python Sets
    • Python Set Methods
    • Priority Queues in Python
    • Reverse Engineering with Python
    • String Formatting in Python
    • Python isinstance
    • String Length Python
    • Python Concurrency
    • Python List
    • Python Initialize List
    • Python Unique List
    • Python Sort List
    • Python Reverse List
    • Python Empty List
    • List Comprehensions Python
    • List Operations in Python
    • Python Database Connection
    • Python SQLite
    • Python SQLite Create Database
    • Send Mail in Python
    • Bash Scripting and Python
    • Violent Python Book
    • NLP in Python
    • Matplotlib In Python
    • Gray Hat Python: Security
    • Python Subprocess
    • Python Threading Timer
    • Python Threadpool
    • Python Statistics Module
    • How to Call a Function in Python?
    • Python Curl
    • JSON in Python
    • Python json.dumps
    • Python Turtle
    • Python Unit Test
    • pass Keyword in Python
    • Tokenization in Python
    • Random Module in Python
    • Python Multiprocessing
    • Python getattr
    • Collection Module in Python
    • Print Statement in Python
    • Python Countdown Timer
    • Python Context Manager
    • File Handling in Python
    • Python Event Handler
    • Python Print Table
    • Python Docstring
    • Python Dictionary Keys
    • Python Iterator Dictionary
    • Python Class Attributes
    • Python Dictionary Methods
    • Namedtuple Python
    • Namedtuple Python
    • Namedtuple Python
    • Python Class Constants
    • Python Validation
    • Python Switch Case
    • Python Rest Server
    • Python Yield vs Return
    • Python Pickle vs JSON
  • Tkinter
    • Tkinter Widgets
    • Python Tkinter Button
    • Python Tkinter Canvas
    • Tkinter Frame
    • Tkinter LabelFrame
    • Python Tkinter Label
    • Tkinter Scrollbar
    • Tkinter Listbox
    • Tkinter Spinbox
    • Tkinter Checkbutton
    • Tkinter Menu
    • Tkinter Menubutton
    • Tkinter OptionMenu
    • Tkinter Messagebox
    • Tkinter Grid
    • Python Tkinter Entry
    • Tkinter after
    • Tkinter Colors
    • Tkinter Font
    • Tkinter PhotoImage
    • Tkinter TreeView
    • Tkinter Notebook
    • Tkinter Bind
    • Tkinter Icon
    • Tkinter Window Size
    • Tkinter Color Chart
    • Tkinter Slider
    • Tkinter Calculator
  • Programs
    • Patterns in Python
    • Star Patterns in Python
    • Swapping in Python
    • Factorial in Python
    • Fibonacci Series in Python
    • Reverse Number in Python
    • Palindrome in Python
    • Random Number Generator in Python
    • Prime Numbers in Python
    • Armstrong Number in Python
    • Strong Number in Python
    • Leap Year Program in Python
    • Square Root in Python
    • Python Reverse String
    • Python Object to String
    • Python Object to JSON
    • Python Classmethod vs Staticmethod
  • Python 3
    • Python 3 Commands
    • Python 3 cheat sheet
  • Interview Question
    • Python Interview Questions And Answers

Related Courses

Python Certification Course

Programming Languages Courses

Angular JS Certification Training

Footer
About Us
  • Blog
  • Who is EDUCBA?
  • Sign Up
  • Corporate Training
  • Certificate from Top Institutions
  • Contact Us
  • Verifiable Certificate
  • Reviews
  • Terms and Conditions
  • Privacy Policy
  •  
Apps
  • iPhone & iPad
  • Android
Resources
  • Free Courses
  • Java Tutorials
  • Python Tutorials
  • All Tutorials
Certification Courses
  • All Courses
  • Software Development Course - All in One Bundle
  • Become a Python Developer
  • Java Course
  • Become a Selenium Automation Tester
  • Become an IoT Developer
  • ASP.NET Course
  • VB.NET Course
  • PHP Course

© 2020 - EDUCBA. ALL RIGHTS RESERVED. THE CERTIFICATION NAMES ARE THE TRADEMARKS OF THEIR RESPECTIVE OWNERS.

EDUCBA
Free Software Development Course

Web development, programming languages, Software testing & others

*Please provide your correct email id. Login details for this Free course will be emailed to you
Book Your One Instructor : One Learner Free Class

Let’s Get Started

This website or its third-party tools use cookies, which are necessary to its functioning and required to achieve the purposes illustrated in the cookie policy. By closing this banner, scrolling this page, clicking a link or continuing to browse otherwise, you agree to our Privacy Policy

EDUCBA

*Please provide your correct email id. Login details for this Free course will be emailed to you
EDUCBA Login

Forgot Password?

EDUCBA
Free Software Development Course

Web development, programming languages, Software testing & others

*Please provide your correct email id. Login details for this Free course will be emailed to you

Special Offer - Python Training Program (36 Courses, 13+ Projects) Learn More