如何在python中有效地比较两个集合列表？

Question

I have a list of sets:

list = [{1,2}, {2,3}, {1,3}, {2,1} etc]

I need a list where every element appears once. creating a set of the list fails with a set is not hashable error If I create another list, and add every element once with if not in list then append list works, but now I have to deal with a list with aroun 600 000 value pairs, and it takes forever. Is there a more efficent way?

Answer 1

Referencing your comment; as you mentioned this worked, I'll post my comment as a proper answer.

set(map(tuple, list_))

Output:

{(1, 2), (1, 3), (2, 3)}

Please note:
I've changed the your list variable named to list_ , as it was overwriting the built-in.

This method appears to scale linearly. Time over a list of 1000 sets was 206 us and 10000 was 2.19 ms.

Answer 2

You can use the following method to perform a union on a list of set:

l = [{1,2}, {2,3}, {1,3}, {2,1}]
set.union(*l)

output:

{1, 2, 3}