Remove a given substring from the end of a string using Python

Python is a programming language used globally and developers use it for different purposes. Python has a variety of different applications such as web development, data science, machine learning, and can also automate different processes. All the different programmers using python have to deal with strings and substrings. So, in this article, we will learn how to remove substring at the end of a string.

Different ways to delete substrings

Use functions

We will use the endswith() function to help us remove the substring at the end of the string. To understand it more clearly, we will give the following example:

Example

def remove_substring(string, substring):  #Defining two different parameters
    if string.endswith(substring):
        return string[:len(string)-len(substring)]   #If substring is present at the end of the string then the length of the substring is removed from the string
    else:
        return string   #If there is no substring at the end, it will return with the same length

# Example 
text = "Hello Everyone, I am John, The Sailor!"
last_substring = ", The Sailor!" #Specifying the substring
#Do not forget to enter the last exclamation mark, not entering the punctuations might lead to error
Without_substring = remove_substring(text, last_substring)
print(Without_substring)

Output

The output of the above code is as follows:

Hello Everyone, I am John

Split string

In this method, we will slice the substring at the end of the string. Python provides functionality to slice text or strings present in the code. We will define the substring in the program and slice it accordingly. Code and examples for removing substrings using this method are as follows:

Example

def remove_substring(string, substring):
    if string[-len(substring):] == substring:  #The length of last characters of the string (length of substring) is compared with the substring and if they are same the substring is removed 
        return string[:-len(substring)]  
    else:
        return string  #If the length of last characters(Substring) does not match with the length of last substring then the characters are not removed 

# Example 
Whole_string = "Hello Everyone, I am John, the Sailor!"
last_substring = ", the Sailor!"
Final_String = remove_substring(Whole_string, last_substring)
print(Final_String)

Output

The output of the above code is as follows:

Hello Everyone, I am John

Re-module

The re module exists in the Python programming language to handle regular functions. We can use one such function from the re module to remove the substring at the end of the string. The function we will use is the re.sub() function. The code and example of using the re module function to delete the last substring of a string are as follows:

Example

import re  #Do not forget to import re module or it might lead to error while running the program

def remove_substring(string, substring):
    pattern = re.escape(substring) + r'$'  #re.escape is used to create a pattern to treat all symbols equally and it includes $ to work only on the substring on the end of the string
    return re.sub(pattern, '', string)  #This replaces the last substring with an empty space

# Example
Whole_string = "Hello Everyone, I am John, the Sailor!"
last_substring = ", the Sailor!"
Final_String = remove_substring(Whole_string, last_substring)
print(Final_String)

Output

The output of the above code is as follows:

Hello Everyone, I am John

Slicing with functions

In this case rfind() function will be used which finds the defined substring starting from the right side and then we can remove the substring with the help of slicing function. You can understand it better with the help of following examples:

Example

def remove_substring(string, substring):
    index = string.rfind(substring)  #rfind() is used to find the highest index of the substring in the string
    if index != -1 and index + len(substring) == len(string):    # If a substring is found, it is removed by slicing the string
        return string[:index]
    else:
        return string   #If no substring is found the original string is returned

# Example 
Whole_string = "Hello Everyone, I am John, the Sailor!"
last_substring = ", the Sailor!"
Final_String = remove_substring(Whole_string, last_substring)
print(Final_String)

Output

The output of the above code is as follows:

Hello Everyone, I am John

Re-module using capture group

This is another way to remove substrings present at the end of a string using the re module. Capturing groups are used with the regular expression module to remove substrings. The code and examples for deleting substrings with the help of capturing groups are as follows:

Example

import re #Do not forget to import the re module or error might occur while running the code

def remove_substring(string, substring):
    pattern = re.escape(substring) + r'(?=$)' # A function is created first and re.escape is used so that all the functions are created equally
    return re.sub(pattern, '', string) # With the help of re.sub() function, the substring will be replaced with empty place

# Example 
Whole_string = "Hello Everyone, I am John, the Sailor!"
last_substring = ", the Sailor!"
Final_String = remove_substring(Whole_string, last_substring)
print(Final_String)

Output

The output of the above code is as follows:

Hello Everyone, I am John

in conclusion

The need to change strings is very common among all users across the globe, but the process of deleting strings many times consumes a lot of time if the correct method is not followed. Therefore, this article describes the many different methods mentioned above that can be used to remove a substring from the end of a string using python. There may be other ways to remove substrings, but the method mentioned in this article is the shortest and simplest suggested method and you can choose according to your application domain.

The above is the detailed content of Remove a given substring from the end of a string using Python. For more information, please follow other related articles on the PHP Chinese website!