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Python | Finding strings with given substring in list
  • Difficulty Level : Expert
  • Last Updated : 24 Dec, 2018

The classical problem that can be handled quite easily by Python and has been also dealt with many times is finding if a string is substring of other. But sometimes, one wishes to extend this on list of strings, and hence then requires to traverse the entire container and perform the generic algorithm.

Let’s discuss certain ways to find strings with given substring in list.

Method #1 : Using list comprehension
List comprehension is an elegant way to perform any particular task as it increases readability in a long run. This task can be performed using naive method and hence can be reduced to list comprehension as well.




# Python code to demonstrate 
# to find strings with substrings 
# using list comprehension 
  
# initializing list 
test_list = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
  
# printing original list 
print ("The original list is : " + str(test_list))
  
# initializing substring
subs = 'Geek'
  
# using list comprehension 
# to get string with substring 
res = [i for i in test_list if subs in i]
  
# printing result 
print ("All strings with given substring are : " + str(res))
Output:
The original list is : ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
All strings with given substring are : ['GeeksforGeeks', 'Geeky']

 
Method #2 : Using filter() + lambda
This function can also perform this task of finding the strings with the help of lambda. It just filters out all the strings matching the particular substring and then adds it in a new list.






# Python code to demonstrate 
# to find strings with substrings 
# using filter() + lambda
  
# initializing list 
test_list = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
  
# printing original list 
print ("The original list is : " + str(test_list))
  
# initializing substring
subs = 'Geek'
  
# using filter() + lambda 
# to get string with substring 
res = list(filter(lambda x: subs in x, test_list))
  
# printing result 
print ("All strings with given substring are : " + str(res))
Output:
The original list is : ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
All strings with given substring are : ['GeeksforGeeks', 'Geeky']

 
Method #3 : Using re + search()
Regular expressions can be used to perform many task in python. To perform this particular task also, regular expressions can come handy. It finds all the matching substring using search() and returns result.




# Python code to demonstrate 
# to find strings with substrings 
# using re + search()
import re
  
# initializing list 
test_list = ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
  
# printing original list 
print ("The original list is : " + str(test_list))
  
# initializing substring
subs = 'Geek'
  
# using re + search()
# to get string with substring 
res = [x for x in test_list if re.search(subs, x)]
  
# printing result 
print ("All strings with given substring are : " + str(res))
Output:
The original list is : ['GeeksforGeeks', 'Geeky', 'Computers', 'Algorithms']
All strings with given substring are : ['GeeksforGeeks', 'Geeky']

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