Given a String list, change every Kth string to uppercase.
Input : test_list = ["gfg", "is", "best", "for", "neveropen"], K = 3 Output : ['GFG', 'is', 'best', 'FOR', 'neveropen'] Explanation : All Kth strings are uppercased. Input : test_list = ["gfg", "is", "best", "for", "neveropen"], 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 listtest_list = ["gfg", "is", "best", "for", "neveropen", "and", "CS"] # printing original listprint("The original list is : " + str(test_list))# initializing K K = 3res = []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)) |
The original list is : ['gfg', 'is', 'best', 'for', 'neveropen', 'and', 'CS'] The resultant String list : ['GFG', 'is', 'best', 'FOR', 'neveropen', 'and', 'CS']
Time Complexity: O(n), where n is length of test_list.
Auxiliary Space: O(n), where n is length of res list to store the result.
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 listtest_list = ["gfg", "is", "best", "for", "neveropen", "and", "CS"] # printing original listprint("The original list is : " + str(test_list))# initializing K K = 3# shorthand to perform this taskres = [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)) |
The original list is : ['gfg', 'is', 'best', 'for', 'neveropen', 'and', 'CS'] The resultant String list : ['GFG', 'is', 'best', 'FOR', 'neveropen', 'and', 'CS']
Time Complexity: O(n)
Auxiliary Space: O(n)
Method #3: Using reduce():
Algorithm:
- Initialize the list test_list with the given strings.
- Print the original list test_list.
- Initialize the value of K to 3.
- Define a lambda function to_upper that takes an index and an element as input and returns the uppercase
- version of the element if the index is a multiple of K, otherwise returns the original element.
- Use the reduce method from the functools module to apply the lambda function to each element of the
- test_list and accumulate the results in a list called res.
- Print the resulting uppercase string list res.
Python3
# Python3 code to demonstrate working of# Every Kth Strings Uppercase# Using reduce method# import reduce from functools modulefrom functools import reduce# initializing listtest_list = ["gfg", "is", "best", "for", "neveropen", "and", "CS"]# printing original listprint("The original list is : " + str(test_list))# initializing KK = 3# define lambda function to convert strings to uppercaseto_upper = lambda idx, elem: elem.upper() if idx % K == 0 else elem# apply lambda function to each element of the list using reduce methodres = reduce(lambda acc, elem: acc + [to_upper(len(acc), elem)], test_list, [])# printing resultprint("The resultant String list : " + str(res))#This code is contributed by Vinay pinjala. |
The original list is : ['gfg', 'is', 'best', 'for', 'neveropen', 'and', 'CS'] The resultant String list : ['GFG', 'is', 'best', 'FOR', 'neveropen', 'and', 'CS']
Time Complexity: O(n), where n is the length of the input list test_list. The reduce method applies the to_upper lambda function to each element of the test_list exactly once, so the time complexity of the reduce method is O(n).
Space Complexity: O(n). The test_list and res lists both have a size of n, where n is the length of the input list. The to_upper lambda function requires constant space, so its space complexity is O(1).
