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Python – Every Kth Strings Uppercase

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  • Last Updated : 24 Aug, 2022
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Given a String list, change every Kth string to uppercase.

Input : test_list = ["gfg", "is", "best", "for", "geeks"], K = 3 
Output : ['GFG', 'is', 'best', 'FOR', 'geeks'] 
Explanation : All Kth strings are uppercased. 

Input : test_list = ["gfg", "is", "best", "for", "geeks"], K = 4 
Output : ['GFG', 'is', 'best', 'for', 'GEEKS'] 
Explanation : All Kth strings are uppercased.

Method #1 : Using loop + upper()

In this, we iterate for all strings using loop and upper is used to perform uppercase, Kth index is detected using modulo operator.

Python3




# Python3 code to demonstrate working of
# Every Kth Strings Uppercase
# Using loop + upper()
 
# initializing list
test_list = ["gfg", "is", "best", "for", "geeks", "and", "CS"]
 
# printing original list
print("The original list is : " + str(test_list))
 
# initializing K
K = 3
 
res = []
for idx in range(len(test_list)):
     
    # checking for Kth index
    if idx % K == 0:
        res.append(test_list[idx].upper())
    else :
        res.append(test_list[idx])
 
# printing result
print("The resultant String list : " + str(res))

Output

The original list is : ['gfg', 'is', 'best', 'for', 'geeks', 'and', 'CS']
The resultant String list : ['GFG', 'is', 'best', 'FOR', 'geeks', 'and', 'CS']

Method #2: Using list comprehension

This is yet another way in which this task can be performed. In this we use list comprehension as shorthand, performs tasks similar to the above method.

Python3




# Python3 code to demonstrate working of
# Every Kth Strings Uppercase
# Using list comprehension
 
# initializing list
test_list = ["gfg", "is", "best", "for", "geeks", "and", "CS"]
 
# printing original list
print("The original list is : " + str(test_list))
 
# initializing K
K = 3
 
# shorthand to perform this task
res = [test_list[idx].upper() if idx % K == 0 else test_list[idx]
       for idx in range(len(test_list))]
 
# printing result
print("The resultant String list : " + str(res))

Output

The original list is : ['gfg', 'is', 'best', 'for', 'geeks', 'and', 'CS']
The resultant String list : ['GFG', 'is', 'best', 'FOR', 'geeks', 'and', 'CS']

Time Complexity: O(n)

Auxiliary Space: O(n)


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