Question

I’m trying to remove duplicates from a nested list only if the first 2 elements are the same, ignoring the third.

List:

L = [['el1','el2','value1'], ['el3','el4','value2'], ['el1','el2','value2'], ['el1','el5','value3']]

Would return:

L = [['el3','el4','value2'], ['el1','el2','value2'], ['el1','el5','value3']]

I found a simple way to do similar here:

dict((x[0], x) for x in L).values()

but this only works for the first element and not the first 2, but that is exactly what I want otherwise.

Answer 1

If the order doesn’t matter, you can use that same method but using a tuple of the first and second elements as the key:

{(x[0], x[1]): x for x in L}.values()

Or on Python versions older than 2.7:

dict(((x[0], x[1]), x) for x in L).values()

Instead of (x[0], x[1]) you can use tuple(x[:2]), use whichever you find more readable.