Finding Strings with Given Substring in List – Python

Last Updated : 31 Jan, 2025

The task of finding strings with a given substring in a list in Python involves checking whether a specific substring exists within any of the strings in a list. The goal is to efficiently determine if the desired substring is present in any of the elements of the list. For example, given a list a = [‘GeeksforGeeks’, ‘Geeky’, ‘Computers’, ‘Algorithms’], the task would be to check if a substring like ‘Geek’ exists.

Using filter

filter() is the efficient built-in method that allows us to filter elements in an iterable based on a condition. When combined with a lambda function, it becomes an elegant way to find strings containing a specific substring.

Python

a = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
b = 'Geek' # Substring 

res = list(filter(lambda x: b in x, a))
print(res)

Output

['GeeksforGeeks', 'Geeky']

Explanation: filter() check if the substring b is in each string of the list a, returning an iterator of matching strings, which is then converted to a list and stored in res.

Using list comprehension

List comprehension is a concise way to filter and create a new list by applying a condition to each element. It is a popular method for its readability and ease of use.

Python

a = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
b = 'Geek' # Substring 

res = [i for i in a if b in i]
print(res)

Output

['GeeksforGeeks', 'Geeky']

Explanation: list comprehension iterate through a, adding strings that contain the substring b to the list res.

Using re.findall()

re module provides powerful string matching tools. re.findall() can be used to find all non-overlapping matches of a substring or pattern in a string. While more complex than the other methods, it is flexible and can be used for more advanced matching needs.

Python

import re
a = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
b = 'Geek' # Substring

res = [i for i in a if re.findall(b, i)]
print(res)

Output

['GeeksforGeeks', 'Geeky']

Explanation :re.findall() checks for occurrences of the substring b in each string of a. If a match is found, the string is included in the list res.

Using any()

any() checks if any element in an iterable is True. When combined with a generator expression, it can be used to find if a substring exists in any string in the list. While it’s less common for this particular task, it can still be useful in certain scenario .

Python

a = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
b = 'Geek' #Substring

res = [i for i in a if any(b in part for part in [i])]
print(res)

Output

['GeeksforGeeks', 'Geeky']

Explanation: any() checks if the substring b is present in the string i from the list a. If found, the string is added to the result list res.