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How to Remove Duplicates from a List in Python [All Method]️

The step-by-step guide on this page will show you How to Remove Duplicates from a List in Python. After completing this guide, you will know how to face these kind problem.
Question: What is the best way to approach this problem? Answer: Check out this blog code to learn how to fix errors How to Remove Duplicates from a List in Python. Question:”What should you do if you run into code errors?” Answer:”By following this blog, you can find a solution.”

We want to remove duplicates from a list, or in other words, keep only unique values in our list.

duplicates = [0, 0, 0, 1, 1, 1, 2, 2, 2]

Using a for Loop

The brute force, inefficient way to remove duplicates is using a for loop, which might look something like this.

unique = []
for num in duplicates:
  if num not in unique:
# [0, 1, 2]

Using set()

We can avoid this loop by simply converting the duplicates list into a set.

By definition, a set will only contain unique items.

We can then convert the set back into a list if needed.

unique = list(set(duplicates))
# [0, 1, 2]

The issue here is that a set is unordered, so the original list order is not guaranteed after the set-to-list conversion.

So, how can we preserve order?

Using dict.fromkeys() to Preserve Order

dict.fromkeys(list) will return a dictionary with the list items as keys. Dictionaries do not allow duplicate keys, so the returned dictionary will remove the duplicates for us while preserving order.

# {0: None, 1: None, 2: None}

We can then convert back to a list.

unique = list(dict.fromkeys(duplicates))
# [0, 1, 2]

Revise the code and make it more robust with proper test case and check an error there before implementing into a production environment.
If you need help at any point, please send me a message and I will do my best to assist you.

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