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Replace Substrings from String List - Python

Python – Remove substring list from String

Last Updated : 10 Jan, 2025

In Python Strings we encounter problems where we need to remove a substring from a string. However, in some cases, we need to handle a list of substrings to be removed, ensuring the string is adjusted accordingly.

Using String Replace in a Loop

This method iterates through the list of substrings and removes each from the string using the replace method.

Python

s = "GeeksforGeeks is an awesome website."  #sub list a = ["Geeks", "awesome"]  # Remove substrings using replace for sub in a:     s = s.replace(sub, "")  print(s)

Output

for is an  website.

Explanation:

The replace() method is used to remove each substring by replacing it with an empty string.
The loop ensures all substrings in sublist ‘a’ are processed.

Let’s explore some more methods and see how we can remove substring list from string.

Table of Content

Using Regular Expressions

Regular expressions provide a powerful way to remove multiple substrings in one step.

Python

import re  s = "GeeksforGeeks is an awesome website." #sublist a = ["Geeks", "awesome"]  # Create a regex pattern from sublist a pattern = "|".join(map(re.escape, a)) s = re.sub(pattern, "", s)  print(s)

Output

for is an  website.

Explanation:

re.escape() ensures special characters in substrings are handled safely.
join() method creates a single pattern matching all substrings.
re.sub() method replaces all occurrences of the pattern with an empty string.

Using List Comprehension and Join

This method builds a filtered string by excluding unwanted substrings.

Python

s = "GeeksforGeeks is an awesome website."  #sublist a = ["Geeks", "awesome"]  # Remove substrings using join and list comprehension result = " ".join(word for word in s.split() if all(sub not in word for sub in a))  print(result)

Output

is an website.

Explanation:

The string is split into words and each word is checked against the sublist ‘a’.
Only words that do not contain any substrings are included in the result.
This method works well for word-level substring removal but might miss partial matches.

Using Reduce from functools

reduce() function allows for successive application of the replace method.

Python

from functools import reduce  s = "GeeksforGeeks is an awesome website." #sublist a = ["Geeks", "awesome"]  # Use reduce to remove substrings res = reduce(lambda acc, sub: acc.replace(sub, ""), a, s)  print(res)

Output

for is an  website.

Explanation:

The reduce() function applies the replace() method iteratively over the substrings.
This approach condenses the logic into a single functional expression.

Using a Custom Function with Loop

A custom function provides flexibility to handle edge cases or additional processing.

Python

def remove_substrings(s, a):     for sub in a:         s = s.replace(sub, "")     return s  s = "GeeksforGeeks is an awesome website." #sublist a = ["Geeks", "awesome"] res = remove_substrings(s, a)  print(res)

Output

for is an  website.

Explanation:

This approach encapsulates the logic in a reusable function.
The function can be extended to handle additional operations if needed.

Replace Substrings from String List - Python

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