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Python – Check if string starts with any element in list

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While working with strings, their prefixes and suffix play an important role in making any decision. Let’s discuss certain ways in which this task can be performed.

Example:

String = "GfG is best"
Input_lis = ['best', 'GfG', 'good']
Output: True
Explanation: 'GfG is best' is present in the list.

String = "GfG is best"
Input_lis = ['Good', 'Bad', 'Nice']
Output: False
Explanation: 'GfG is best' is not present in the list.

Check if a string starts with any element in a list using string startswith()

This task can be handled solely by using string startswith() supplying a prefix checklist as an argument to a method as well.

Python3




# initializing string
test_string = "GfG is best"
 
# initializing prefix list
pref_list = ['best', 'GfG', 'good']
 
# printing original string
print("The original string : "
    + str(test_string))
 
# using startswith()
# Prefix tests in Strings
res = test_string.startswith(tuple(pref_list))
 
# print result
print("Does string start with any prefix list sublist ? : "
    + str(res))


Output

The original string : GfG is best
Does string start with any prefix list sublist ? : True

Check if a string starts with any element in a list using filter()

The filter() method is used to check for each word and startswith() method tests for the prefixing logic at the target list. 

Python3




# initializing string
test_string = "GfG is best"
 
# initializing prefix list
pref_list = ['best', 'GfG', 'good']
 
pref_list1 = ['Geeksforgeeks']
 
# printing original string
print("The original string : " + str(test_string))
 
# test True case
res = list(filter(test_string.startswith, pref_list)) != []
 
# print result
print("Does string start with any prefix list sublist ? : " + str(res))
 
# test False case
res = list(filter(test_string.startswith, pref_list1)) != []
 
print("Does string start with any prefix list sublist ? : " + str(res))


Output

The original string : GfG is best
Does string start with any prefix list sublist ? : True
Does string start with any prefix list sublist ? : False

Check if a string starts with any element in a list using in operator

In this example, we are using a Python loop to check if the existing string words are contained in a list or not. Here, we first assigned res to false, if the condition gets satisfied then the result becomes True.

Python3




# initializing string
test_string = "GfG is best"
 
# initializing prefix list
pref_list = ["cat", "dog"]
 
# printing original string
print("The original string : " + str(test_string))
 
res=False
x=test_string.split()
if(x[0] in pref_list):
    res=True
 
# print result
print("Does string start with any prefix list sublist ? : " + str(res))


Output

The original string : GfG is best
Does string start with any prefix list sublist ? : False

Time complexity: O(n), where n is the length of the prefix list. 
Auxiliary space: O(1) as we are not using any additional data structures.

Using find() method

Python3




# Python3 code to demonstrate
# Prefix tests in Strings
 
# initializing string
test_string = "GfG is best"
 
# initializing prefix list
pref_list = ['best', 'GfG', 'good']
 
# printing original string
print("The original string : " + str(test_string))
 
res=False
for i in pref_list:
    if(test_string.find(i)==0):
        res=True
# print result
print("Does string start with any prefix list sublist ? : " + str(res))


Output

The original string : GfG is best
Does string start with any prefix list sublist ? : True

Time complexity: O(n)

Auxiliary space: O(1)

 Using operator.countOf() method

Python3




# Python3 code to demonstrate
# Prefix tests in Strings
import operator as op
# initializing string
test_string = "GfG is best"
 
# initializing prefix list
pref_list = ['best', 'GfG', 'good']
 
# printing original string
print("The original string : " + str(test_string))
 
res = False
for i in pref_list:
    if(op.countOf(test_string, i) == 0):
        res = True
# print result
print("Does string start with any prefix list sublist ? : " + str(res))


Output

The original string : GfG is best
Does string start with any prefix list sublist ? : True

Time Complexity: O(n)
Auxiliary Space: O(1)

Using regular expressions

Python3




import re
 
# initializing string
test_string = "GfG is best"
 
# initializing prefix
pref = 'best'
 
# printing original string
print("The original string : " + str(test_string))
 
# using regular expressions
res = re.match("^" + pref, test_string)
 
# print result
print("Does string start with prefix ? : " + str(bool(res)))
#This code is contributed by Vinay Pinjala.


Output

The original string : GfG is best
Does string start with prefix ? : False

Time Complexity: O(n)
Auxiliary Space: O(1)



Last Updated : 20 Apr, 2023
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