How to efficiently compare two unordered lists (not sets) in Python?

Question

a = [1, 2, 3, 1, 2, 3]
b = [3, 2, 1, 3, 2, 1]

a & b should be considered equal, because they have exactly the same elements, only in different

Answer 1

If the list contains items that are not hashable (such as a list of objects) you might be able to use the Counter Class and the id() function such as:

from collections import Counter
...
if Counter(map(id,a)) == Counter(map(id,b)):
    print("Lists a and b contain the same objects")