How to remove identical lists from a list of lists?

Question

I'd like to remove same lists in a list having len(a) = 5 and a = [[1,2,3],[2,3,4], [0,1,2],[2,4,6],[3,6,9]] as results. How can I get that?

a1 = [[1,2,3],[2,3,4]]
a2 = [[0,1,2],[2,4,6]]
a3=[[1,2,3],[0,1,2],[3,6,9]]
a = a1+a2+a3
a = [tuple(l) for l in a]
print(set(a))
print(len(a))
a=[list(ele) for ele in a]
print(a)
print(len(a))

Answer 1

You cannot make a set of lists of lists because they are not hashable. You could first convert them to tuples and then create a set:

a1 = [[1,2,3],[2,3,4]]
a2 = [[0,1,2],[2,4,6]]
a3=[[1,2,3],[0,1,2],[3,6,9]]
a = a1+a2+a3
a = [list(x) for x in set([tuple(L) for L in a])]

output:

[[0, 1, 2], [2, 4, 6], [1, 2, 3], [2, 3, 4], [3, 6, 9]]