How can I merge two lists in Python while removing duplicates but preserving the original order? [duplicate]

Question

I have two lists in Python:

list1 = [1, 2, 3, 4]
list2 = [3, 4, 5, 6]

I want to merge them into a single list such that:

1. No duplicates remain
2. The original order of elements is preserved

For the example above, the desired output is: [1, 2, 3, 4, 5, 6].

I tried using list(set(list1 + list2)) but it doesn't preserve the order. How can I achieve this efficiently in Python?

Answer 1

You can try dict.fromkeys()

list1 = [1, 2, 3, 4]
list2 = [3, 4, 5, 6]

merged = list(dict.fromkeys(list1 + list2))
print(merged) 


output

[1, 2, 3, 4, 5, 6]