Remove the given Substring from the End of a String using Python

When working with strings in Python, you may need to remove a specific substring from the end of a string. Python provides several built-in methods to accomplish this task efficiently, from simple string methods to regular expressions.

Using endswith() Method

The endswith() method checks if a string ends with a specific substring, making it perfect for conditional removal ?

def remove_substring(string, substring):
    if string.endswith(substring):
        return string[:len(string)-len(substring)]
    else:
        return string

# Example 
text = "Hello Everyone, I am John, The Sailor!"
last_substring = ", The Sailor!"
result = remove_substring(text, last_substring)
print(result)

Hello Everyone, I am John

Using String Slicing

String slicing allows you to compare and remove substrings by checking the last characters of the string ?

def remove_substring(string, substring):
    if string[-len(substring):] == substring:
        return string[:-len(substring)]
    else:
        return string

# 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)

Hello Everyone, I am John

Using re Module

The re.sub() function with regular expressions provides powerful pattern matching for substring removal ?

import re

def remove_substring(string, substring):
    pattern = re.escape(substring) + r'$'
    return re.sub(pattern, '', string)

# 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)

Hello Everyone, I am John

Using rfind() with Slicing

The rfind() method finds the last occurrence of a substring and verifies it's at the string's end ?

def remove_substring(string, substring):
    index = string.rfind(substring)
    if index != -1 and index + len(substring) == len(string):
        return string[:index]
    else:
        return string

# 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)

Hello Everyone, I am John

Using removesuffix() (Python 3.9+)

Python 3.9 introduced removesuffix(), the most straightforward method for this task ?

# Example using removesuffix()
text = "Hello Everyone, I am John, the Sailor!"
suffix = ", the Sailor!"
result = text.removesuffix(suffix)
print(result)

Hello Everyone, I am John

Comparison

Conclusion

Use removesuffix() if you're using Python 3.9+, otherwise endswith() provides the clearest approach. Choose re.sub() only when you need complex pattern matching for substring removal.