Get a set of 2d list in python

Question

I have a list like follows:

t=[[1, 7], [3, 7], [1, 7], [5, 8], [3, 7]]

I need to get a set out of this so the output would be like:

t=[[1, 7], [3, 7], [5, 8]]

I tried to use t = set(t) but it didn't work.

Answer 1

If you do not care about the order, you can first convert the inner lists to tuples using map() function, and then convert them to set and then back to list .

Example -

>>> t=[[1, 7], [3, 7], [1, 7], [5, 8], [3, 7]]
>>> t = list(set(map(tuple,t)))
>>> t
[(3, 7), (5, 8), (1, 7)]

Answer 2

The problem is that, lists are mutable and thus one cannot make a set out of them as they might change. Thus you want to use tuples which are immutable. Thus you can use:

list(set([tuple(ti) for ti in t]))