icanbeyourmuse last edited by
Okay, I am trying to advance my coding skills (I hassle Theno a lot) but I don't really understand how setunion() works. There's a few others I don't understand but, atm, this is the one I am focusing on trying to understand. I was trying 'just doing' but it does not seem to be clear to me still. Anyone able to help a gal out?
Do you know about Venn Diagrams?
Union: add the two circles together.
Intersect: just the part where the circles overlap.
Difference: the first circle minus the second circle.
Each circle is called a 'set', as in a set of numbers, a set of words, a set of shapes.
Union: everything from both sets.
Intersect: only things that are in both sets
Difference: things in the first set that are not in the second set (set1 - intersect)
On Mu*, the set functions will also sort and return one, and only one, of each item, you may start with 'a a a', but you will end up with 'a'. (Aka, a distinct set.)
All sets are composed of distinct, or uniquely identifiable, objects. The basics.
Set operations are useful for combining (or separating) groups of things you are interested (or not interested) in operating upon.
Consider use-case: What friends of mine are online now? (set-intersection of lwho and your private list of friends)
union of (a b c d) (c e f g) -> (a b c d e f g)
intersection of (a b c d) (c e f g) -> (c)
Often you'll see mushcode like
setunion(%va,)or similar. What this is doing is saying "perform a simple (lexicographical) sort on the elements of %va, remove any duplicates, and return it."