Split string on Kth Occurrence of Character - Python

The task is to write Python program to split a given string into two parts at the Kᵗʰ occurrence of a specified character. If the character occurs fewer than K times return the entire string as the first part and an empty string as the second part. For example, in the string "a,b,c,d,e,f", splitting at the 3rd occurrence of "," gives ['a', 'b', 'c', 'd,e,f'].

Using String's split and join

Using a string's split() and join() methods allows for efficient manipulation of text split() method divides a string into a list of substrings based on a specified delimiter.

s = "hello,world,how,are,you"
k = 2
char = ","
# Splitting the string at the first 2 commas (k=2)
parts = s.split(char, k)

# Joining the first k parts with commas, and then adding the remaining part after the k-th split
res = char.join(parts[:k]) + char + parts[k]
print(res) 

hello,world,how,are,you

Explanation:

• String is split at the Kth occurrence of the character.
• Result is reconstructed by joining the first k parts and then adding the rest after the Kth occurrence.

Using a Loop

Using a loop with string manipulation allows us to iterate over each character or a substring enabling us to perform operations such as transforming, filtering, or counting elements.

s = "hello,world,how,are,you"
k = 2
char = ","
count = 0  #
# Creating an empty list to store characters up to the k-th occurrence of the delimiter
result = []
for i in range(len(s)):
    result.append(s[i])  # Appending each character to the result list
    if s[i] == char:  # If the character is a comma, increment the count
        count += 1
    if count == k:  # If the k-th comma is found, stop further iterations
        break

# Joining the result list and adding the remaining part of the string after the k-th comma
res = ''.join(result) + s[i + 1:]
print(res) 

hello,world,how,are,you

Explanation:

• Iterate over the string and append characters to the result list until the Kth occurrence of the character is found.
• After the Kth occurrence, append the rest of the string starting from the next character

Using re.split with a Pattern

re.split() method in Python allows splitting a string based on a regular expression pattern. This method provides more flexibility than the standard split() by enabling complex delimiter patterns.

import re

s = "hello,world,how,are,you"
k = 2
char = ","
pattern = f"({re.escape(char)})"
parts = re.split(pattern, s, maxsplit=k)
res = ''.join(parts[:k+1])
print(res)  

hello,world

Explanation:

• re.split splits the string up to the Kth occurrence of the character.
• Regular expression captures the character itself, and the result is joined back to preserve the separator.