Python: How to Remove Duplicates From the List

In this post, I have shared top ideas to remove duplicates from the list. Those are with Append and Dictionary.

Python: How to Remove Duplicates From List

1. How to Remove Duplicates Using Append?

# Here is a list with duplicates

list_with_duplicates = [1,2,3,12,1,2,3,4,5,6,1,2,3,7,8,9]

It is simple if you follow the first-approach - brute force approach:

list_without_duplicates = []

for pd in list_with_duplicates:
  if pd not in list_without_duplicates:


[1, 2, 3, 12, 4, 5, 6, 7, 8, 9]

This method has performance issues when the list is bigger in size. 


Idea 1:  Remove Duplicates Using Append.

2. How to Remove Duplicates Using Dictionary?

# Here is you can convert a list to a dictionary

dict_without_duplicates = dict(zip(list_with_duplicates, list_with_duplicates))


{1: 1, 2: 2, 3: 3, 12: 12, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9}


Idea 2: Remove Duplicates Using Dictionary.

Once again, this works and has the advantage of taking less space than duplicating the entire list. 

*Notes: Of course, we still need to convert it back to a list when we did, which will be somewhat painful since we must extract the keys and add them to a list.


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