Pythonic way of removing reversed duplicates in list

Question

I have a list of pairs:

[0, 1], [0, 4], [1, 0], [1, 4], [4, 0], [4, 1]

and I want to remove any duplicates where

[a,b] == [         


        

Answer 1

Well, I am "checking for the reverse pair and append to a list if that's not the case" as you said you could do, but I'm using a single loop.

x=[[0, 1], [0, 4], [1, 0], [1, 4], [4, 0], [4, 1]]
out = []
for pair in x:
    if pair[::-1] not in out:
        out.append(pair)
print out

The advantage over existing answers is being, IMO, more readable. No deep knowledge of the standard library is needed here. And no keeping track of anything complex. The only concept that might be unfamiliar for beginners it that [::-1] reverts the pair.

The performance is O(n**2) though, so do not use if performance is an issue and/or lists are big.