获得三个列表的补充

Question

I have three lists:
a = [1, 2, 3, 4] b = [2, 3, 4, 5] c = [3, 4, 5, 6]

My goal is to get all values which are not present in all of the three lists: [1,2,5,6]
Basically I am searching the "negation" of set(a) & set(b) & set(c) .

An efficient solution would be appreciated since the lists are very long.

Answer 1

The opposite of set(a) & set(b) & set(c) is already explained in this question as stated by Chris_Rands in the comments:

>>> (set(a) | set(b) | set(c)) - (set(a) & set(b) & set(c))
{1, 2, 5, 6}

For really long lists, using numpy should be may efficient:

import numpy as np
from functools import reduce

a = [1, 2, 3, 4]
b = [2, 3, 4, 5]
c = [3, 4, 5, 6]

union = reduce(numpy.union1d, (a,b,c))
intersect = reduce(numpy.intersect1d, (a,b,c))
print(numpy.setdiff1d(union, intersect))

Output:

[1 2 5 6]