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Python – Replace to K at ith Index in String

  • Last Updated : 02 Sep, 2020

Given a String, replace ith index by K value.

Input : test_str = ‘geeks5geeks’, K = ‘7’, i = 5
Output : ‘geeks7geeks’
Explanation : Element is 5, converted to 7 on ith index.

Input : test_str = ‘geeks5geeks’, K = ‘7’, i = 6
Output : ‘geeks56eeks’
Explanation : Element is g, converted to 7 on ith index.

Method #1 : Using string slicing

In this, we perform the slicing of pre string, till i, and then add K, then add post values, using string slice method.

Python3




# Python3 code to demonstrate working of 
# Replace to K at ith Index in String
# using string slicing
  
# initializing strings
test_str = 'geeks5geeks'
  
# printing original string
print("The original string is : " + str(test_str))
  
# initializing K
K = '4'
  
# initializing i
i = 5
  
# the replaced result 
res = test_str[: i] + K + test_str[i + 1:]
  
# printing result 
print("The constructed string : " + str(res)) 
Output
The original string is : geeks5geeks
The constructed string : geeks4geeks

Method #2 : Using join() + generator expression

In this, we perform the task of checking for ith index and conditionally appending K, using generator expression and convert the result into string using join().

Python3




# Python3 code to demonstrate working of 
# Replace to K at ith Index in String
# using join() + generator expression
  
# initializing strings
test_str = 'geeks5geeks'
  
# printing original string
print("The original string is : " + str(test_str))
  
# initializing K
K = '4'
  
# initializing i
i = 5
  
# the replaced result 
res = ''.join(test_str[idx] if idx != i else K for idx in range(len(test_str)))
  
# printing result 
print("The constructed string : " + str(res)) 
Output
The original string is : geeks5geeks
The constructed string : geeks4geeks


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