how to run issubset/issuperset on a list of sets will iterating through that list

Question

i'm trying to figure out how i can identify which objects are a subset/superset within the list that holds them. and thereby remove them from the list.

if i have list a = [ {'john-123'}, {'john-123','john-234'}, {'john-123','john-234','johnnybegood'} ]

the first two are subsets of the last one.

i've found a lot about comparing two different sets, but not sure how to implement that into an iteration

i've tried something like this:

for j in a: frequency = sum(j.issubset(b) for b in a) print(frequency)

but no dice

I dont understand what you are looking for. What do you expect for the example you give? What do you mean with 'no dice'? (sry, maybe my english isnt that good) — H. Doebler
– H. Doebler, Commented Aug 25, 2021 at 21:06
@H.Doebler well... for each j in the list (meaning for each set in the list) i want to identify if it is a subset or not. no dice means, unlucky or 'isn't working' — avnav99
– avnav99, Commented Aug 25, 2021 at 21:10
A subset of what? A subset of any set in the list? A subset of all sets in the list? A subset of all subsequent subsets in the list? — H. Doebler
– H. Doebler, Commented Aug 25, 2021 at 21:12
@H.Doebler whether it is a a subset of any other set in the same list. — avnav99
– avnav99, Commented Aug 25, 2021 at 21:13
Ok, obviously every set in the list is a subset of itself. But you want the list of elements that are a subset of an other set in the list. Can you assume that the list's elements are unique? I.e. is a = [{1}, {1,2}, {1}] a possible input to your problem? — H. Doebler
– H. Doebler, Commented Aug 25, 2021 at 21:17

H. Doebler · Accepted Answer · 2021-08-25 21:25:40Z

The problem in your approach is that you test every element in the list against every element in the list, not every other element. Since every set is a subset of itself, you will always get the whole list as an answer.

Try this:

a = [{1}, {2}, {1,2}, {1,3}, {1,3,4}]

Clearly, {1,2} and {1,3,4} are not subsets of other sets in a.

subsets = [b for b in a if any(b.issubset(c) and b != c for c in a)] print(subsets) [{1}, {2}, {1, 3}]

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