How to remove duplicate elements from a List in Python

Pratik Choudhari

A list data structure is capable of storing elements of different data types and multiple occurrences. In some cases, lists need to be deduplicated, which means we have to remove copies of elements from the data structure.

In this article, we will see how duplicates can be removed from a list using plain python and numpy

1. Using Set

Set is made of only unique elements, duplicate insertions are ignored. In this approach, first the list is typecasted to a set and then typecasted back into a list.

duplicate_list = [56, 4, 81, 56, 9, 4] cleaned_list = list(set(duplicate_list)) print(cleaned_list)


[56, 81, 4, 9]

It is important to note that typecasting into a set does not preserve the order.

2. Using dict.fromkeys()

Using this approach, order can be preserved. dict in python has a method fromkeys() which takes in an iterable of hashable objects and creates a dictionary from them, while setting all values as None.

duplicate_list = [56, 4, 81, 56, 9, 4] cleaned_list = list(dict.fromkeys(duplicate_list)) print(cleaned_list)


[56, 4, 81, 9]

3. Using numpy.unique(duplicate_list)

Numpy is known for it’s versatility in dealing with array operations. Using numpy.unique() does not preserve order rather it sorts the array in ascending order.

import numpy as np duplicate_list = [56, 4, 81, 56, 9, 4] cleaned_list = list(np.unique(dupllicate_list)) print(cleaned_list)


[4, 9, 56, 81]

FREE VS Code / PyCharm Extensions I Use

✅ Write cleaner code with Sourcery, instant refactoring suggestions: Link *

* This is an affiliate link. By clicking on it you will not have any additional costs, instead you will support me and my project. Thank you! 🙏

Check out my Courses