Python - Replace duplicate Occurrence in String

Python - Replace duplicate Occurrence in String

Let's explore a tutorial on how to replace subsequent duplicate occurrences of substrings in a given string.

Objective:

Given a string and a target substring, replace all but the first occurrence of that substring with a specified replacement string.

Sample Input:

s = "appleappleapple" target = "apple" replacement = "orange"

Expected Output:

"appleorangeorange"

Tutorial:

Step 1: Find the first occurrence of the target substring. Use the string's find() method to get the index.

Step 2: Replace subsequent occurrences of the target substring with the replacement string.

def replace_duplicate_occurrences(s, target, replacement): # Find the first occurrence of the target first_occurrence_index = s.find(target) # If target not found or found at the end, return the string as is if first_occurrence_index == -1 or first_occurrence_index == len(s) - len(target): return s # Split the string at the end of the first occurrence start = s[:first_occurrence_index + len(target)] end = s[first_occurrence_index + len(target):] # Replace the target with the replacement in the latter half end = end.replace(target, replacement) return start + end

Step 3: Test the function using the sample input.

s = "appleappleapple" print(replace_duplicate_occurrences(s, "apple", "orange")) # Output: "appleorangeorange"

Additional Points:

  1. Multiple Substrings: Extend the function to handle replacements for multiple substrings. You can loop over a dictionary of target-replacement pairs, applying the replacement logic for each pair.

  2. Regular Expressions: Using Python's re module, you can handle more complex patterns and replacements. This is especially helpful when working with patterns instead of fixed substrings.

  3. Non-overlapping Replacements: The current solution considers non-overlapping replacements. If the target substrings can overlap, additional logic or regular expressions might be required.

Recap:

In this tutorial, you've learned how to replace all but the first occurrence of a specified substring in a string. This technique can be especially useful when de-duplicating or normalizing data.

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