How to Remove Duplicates in a List in Python

How to Remove Duplicates in a List in Python ?

Answer

To remove duplicates from a list in Python while maintaining the order of elements, you can use a combination of a for loop and a set to keep track of seen elements.

✐ Examples

1 Remove Duplicates from a List While Maintaining Order

In this example,

We create a list named original_list with some duplicate elements.
We initialize an empty list unique_list to store the elements without duplicates.
We initialize an empty set seen to keep track of elements that have already been added to unique_list.
The outer loop iterates over each element in original_list.
Inside the outer loop, we check if the element is not in the seen set.
If the element is not in the seen set, we add it to unique_list and also add it to the seen set to mark it as processed.
Finally, we print the unique_list to standard output.

Python Program

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

for item in original_list:
    if item not in seen:
        unique_list.append(item)
        seen.add(item)

print(unique_list)

Output

[1, 2, 3, 4, 5]

2 Remove Duplicates from a List of Strings While Maintaining Order

In this example,

We create a list named original_list with some duplicate string elements.
We initialize an empty list unique_list to store the elements without duplicates.
We initialize an empty set seen to keep track of elements that have already been added to unique_list.
The outer loop iterates over each element in original_list.
Inside the outer loop, we check if the element is not in the seen set.
If the element is not in the seen set, we add it to unique_list and also add it to the seen set to mark it as processed.
Finally, we print the unique_list to standard output.

Python Program

original_list = ["apple", "banana", "apple", "orange", "banana"]
unique_list = []
seen = set()

for item in original_list:
    if item not in seen:
        unique_list.append(item)
        seen.add(item)

print(unique_list)

Output

['apple', 'banana', 'orange']

Summary

In this tutorial, we learned How to Remove Duplicates in a List in Python language with well detailed examples.

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How to Remove Duplicates in a List in Python

How to Remove Duplicates in a List in Python ?

Answer

✐ Examples

1 Remove Duplicates from a List While Maintaining Order

Python Program

Output

2 Remove Duplicates from a List of Strings While Maintaining Order

Python Program

Output

Summary

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