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Home Forums How to remove duplicate elements from a list in Python? – MindStick
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1 Answers

Aryan Kumar
Aryan Kumar 05 Jul 2023
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There are several ways to remove duplicates elements from a list in Python. Here are some of the most common methods:

  • Using a set: A set is a data structure that cannot have duplicate elements. So, if you convert a list to a set, the duplicates will be automatically removed.

Python

def remove_duplicates_using_set(list1):
    unique_list = set(list1)
    return list(unique_list)


list1 = [1, 2, 3, 4, 5, 1, 2, 3]
unique_list = remove_duplicates_using_set(list1)
print(unique_list)
  • Using a dictionary: A dictionary can also be used to remove duplicates from a list. The dictionary will store the elements of the list as keys, and the values will be 1. If an element already exists in the dictionary, the value will be incremented by 1. So, the keys in the dictionary will be the unique elements in the list.

Python

def remove_duplicates_using_dictionary(list1):
    unique_list = []
    dictionary = {}
    for item in list1:
        if item not in dictionary:
            unique_list.append(item)
            dictionary[item] = 1
        else:
            dictionary[item] += 1
    return unique_list


list1 = [1, 2, 3, 4, 5, 1, 2, 3]
unique_list = remove_duplicates_using_dictionary(list1)
print(unique_list)
  • Using a for loop: You can also use a for loop to remove duplicates from a list. The basic idea is to iterate through the list, and if an element is not already in a new list, then add it to the new list.

Python

def remove_duplicates_using_for_loop(list1):
    unique_list = []
    for item in list1:
        if item not in unique_list:
            unique_list.append(item)
    return unique_list


list1 = [1, 2, 3, 4, 5, 1, 2, 3]
unique_list = remove_duplicates_using_for_loop(list1)
print(unique_list)

Which method you use to remove duplicates from a list in Python depends on your specific needs. If you need to remove duplicates quickly, then using a set or a dictionary is a good option. If you need to preserve the order of the elements in the list, then using a for loop is a good option.

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