If we want to go golfing :), my favorite solution is with the python 2.6 versions of intersection and union: set_union = set().union(*sets) set_intersection = set.universal().intersection(*sets) Folds are nice. That's actually why I sent my initial email to the list. It's really annoying to having appropriate identity element for union built in while missing the *correct* identity element for intersection. Andy. On Jul 23, 3:12 am, Andrew Bennetts <and...@bemusement.org> wrote:
Andy Kish wrote:
[...]
The above intersection case would end up looking something like:
set_intersection = set.universal() for s in sets: set_intersection &= s
Or even:
set_intersection = reduce(operator.and_, sets, set.universal())
Although, you can already pass multiple (or zero) sets to set.intersection(). So your special case version can be a little simpler...
sets = list(sets) if len(sets) == 0: return set() return sets[0].intersection(sets[1:])
Which isn't as elegant, but it's also not so bad.
-Andrew.
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