Remove All Duplicates From List Python

Chapter: Python Last Updated: 04-10-2023 17:41:28 UTC

Program:

            /* ............... START ............... */
                
# Using a Set (Recommended for maintaining the order of the original list):

original_list = [1, 2, 2, 3, 4, 4, 5]
unique_list = list(set(original_list))


# Using a Loop (Preserves order):

original_list = [1, 2, 2, 3, 4, 4, 5]
unique_list = []
for item in original_list:
    if item not in unique_list:
        unique_list.append(item)


# Using List Comprehension (Preserves order):

original_list = [1, 2, 2, 3, 4, 4, 5]
unique_list = [x for i, x in enumerate(original_list) if x not in original_list[:i]]

                /* ............... END ............... */
        

Notes:

• In first program we convert the list to a set, which automatically removes duplicates, and then convert it back to a list to maintain the order. Note that this method will only work for lists containing hashable elements.
• In second program method iterates through the original list and appends each unique item to the unique_list if it hasn't been added already. It preserves the order of the original list.
• Last program uses a list comprehension to build the unique_list by checking if an element is not present in the portion of the original list before the current index.
• Choose the method that best suits your needs. The first method using a set is the most efficient for large lists, but it may not preserve the order of elements. The other two methods preserve the order but may be less efficient for very large lists.

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