[Newbies] Re: Another extension proposal -> subsets

[Klaus D. Witzel]

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
>>