How to remove duplicates in nested lists?

Question

I want to remove both duplicates and permutations from my nested list.

Input:

[[-1, 0, 1], [-1, 1, 0], [-1, 2, -1], [-1, 2, -1], [-1, -1, 2]]

Expected Output:

[[-1, 0, 1], [-1, 2, -1]]

I tried using a list comprehension but I end up with the output as

[[-1, 1, 0], [-1, 2, -1], [-1, 0, 1], [-1, -1, 2]]

Here is what I attempted.

a = [[-1, 0, 1], [-1, 1, 0], [-1, 2, -1], [-1, 2, -1], [-1, -1, 2]]
b_set = set(tuple(x) for x in a)
b = [ list(x) for x in b_set ]
print(b)

Selcuk · Accepted Answer · 2019-01-14 05:51:59Z

4

The result is expected because [-1, 0, 1] != [-1, 1, 0]. You can sort the inner tuples if you want to make sure that they are considered equal:

b_set = set(tuple(sorted(x)) for x in a)

answered Jan 14, 2019 at 5:51

Selcuk

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Comments

U13-Forward · Accepted Answer · 2019-01-15 00:20:03Z

1

Or with map:

b_set = set(map(lambda x: tuple(sorted(x)),a))

answered Jan 14, 2019 at 5:54

U13-Forward

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