On Thu, 24 Jul 2008 18:27:48 +0200, Cedrick wrote:
or withNicolas suggestion:Set>>asPowerset | subset | subset := (OrderedCollection new: (2 raisedTo: self size)) add: Set new; yourself. 1 to: self size do: [:subSize | "don't copy anymore as there is the Set conversion" self asArray combinations: subSize atATimeDo: [:subArray | subset add: subArray asSet]]. ^ subset asSet
Ah, you francophones always want to see Blaise Pascal's triangle at work ;) Didn't check #combinations:* implementation, does it avoid #includes: ?
I'd still prefer #combinationsSize:do: instead of #combinations:atATimeDo:
+1 but it looks alt-w friendly already (like #detectSum: looks ;)
How about naming Collection>>#asPowerset ^ self asSet powersetInto: (Set new: (2 raisedTo: self size)) with Set>>#powersetInto: and putting that into the next release. /Klaus
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