Python – Mid occurrence of K in string

Given a String, the task is to write a Python program to extract the mid occurrence of a character. 

Input : test_str = “geeksforgeeks is best for all geeks”, K = ‘e’

Output : 10

Explanation : 7 occurrences of e. The 4th occurrence [mid] is at 10th index.

Input : test_str = “geeksforgeeks is best for all geeks”, K = ‘g’

Output : 8

Explanation : 3 occurrences of g. The 2nd occurrence [mid] is at 8th index.

Method #1 : Using enumerate() + list comprehension

In this, we perform the task of getting all occurrences using list comprehension and enumerate gets all indices. Post that the middle element of the list is printed to get mid occurrence of a character.

Python3

# Python3 code to demonstrate working of
# Mid occurrence of K in string
# Using find() + max() + slice

# initializing string
test_str = "geeksforgeeks is best for all geeks"

# printing original string
print("The original string is : " + str(test_str))

# initializing K
K = 'e'

# getting all the indices of K
indices = [idx for idx, ele in enumerate(test_str) if ele == K]

# getting mid index
res = indices[len(indices) // 2]

# printing result
print("Mid occurrence of K : " + str(res))

Output:

The original string is : geeksforgeeks is best for all geeks
Mid occurrence of K : 10

Time Complexity: O(n)

Space Complexity: O(n)

Method #2 : Using finditer() + list comprehension + regex

In this, the character is found using regex and finditer(). The mid occurrence is the mid element of the indices list.

Python3

# Python3 code to demonstrate working of
# Mid occurrence of K in string
# Using finditer() + list comprehension + regex
import re

# initializing string
test_str = "geeksforgeeks is best for all geeks"

# printing original string
print("The original string is : " + str(test_str))

# initializing K
K = 'e'

# getting all the indices of K
# using regex
indices = [ele.start() for ele in re.finditer(K, test_str)]

# getting mid index
res = indices[len(indices) // 2]

# printing result
print("Mid occurrence of K : " + str(res))

Output:

The original string is : geeksforgeeks is best for all geeks
Mid occurrence of K : 10

Time Complexity: O(n)

Auxiliary Space: O(n)