How to Remove Duplicate Values from a List in Python

78 views

How to Remove Duplicate Values from a List in Python

How to Remove Duplicate Values from a List in Python

I have a list with duplicate values, and I need to remove the duplicates while maintaining the order of elements. How can I achieve this?

solveurit24@gmail.com Changed status to publish February 16, 2025
0

Removing duplicates from a list in Python while preserving the order of elements can be done using a combination of a loop and a set. Here’s how you can do it:

  1. Using a Set to Track Duplicates:
    • Create an empty set to keep track of elements that have already been seen.
    • Create a new list to store the elements without duplicates.
    • Iterate through the original list, and for each element, check if it’s in the set.
    • If it’s not in the set, add it to the set and the new list.
  2. Code Example:

    my_list = [1, 2, 2, 3, 4, 4, 4, 5]
    seen = set()
    unique_list = []
    for item in my_list:
        if item not in seen:
            seen.add(item)
            unique_list.append(item)
    print("Original list:", my_list)
    print("List without duplicates:", unique_list)
    

  3. Alternative Method for Python 3.7+:
    • If you’re using Python 3.7 or newer, you can leverage the insertion-order preservation feature of dictionaries. Use the dict.fromkeys() method.
    my_list = [1, 2, 2, 3, 4, 4, 4, 5]
    unique_list = list(dict.fromkeys(my_list))
    print("List without duplicates:", unique_list)
    

Explanation:

  • Using a Set: This method ensures that you track elements efficiently, as sets have average O(1) time complexity for membership checks.
  • Preserving Order: Both methods maintain the order of elements as they appeared in the original list.

These techniques allow you to remove duplicates from a list while preserving the order, depending on your Python version and use case.

solveurit24@gmail.com Changed status to publish February 16, 2025
0