Set intersection with custom comparator?

Question

I have sets of strings

set_a = {'abcd', 'efgh', 'ghij'}
set_b = {'abce', 'efgk', 'ghij'}

I want to find the intersection between these two sets but element equality defined as the following

def match(string_a, string_b, threshold=0.8):
    lcs_len = lcs(string_a, item_set_b)
    return (lcs_len / max(len(string_a), len(item_set_b))) > 0.8

basically if the lcs is at least 80% of the length of the string we consider this matching "enough". I know passing custom comparators to sorting methods works something like this but I haven't found anything for custom comparators in set operations.

Answer 1

You can iterate over the cartesian product of both sets, then keep the elements that are in both sets and satisfy your predicate

from itertools import product
{i for i,j in product(set_a, set_b) if i in set_b and match(i,j)}