From: Mathieu Bouchard <matju@...>
Date: 2001-05-27T12:16:22+09:00
Subject: [ruby-talk:15787] Re: Subsets of a set

On Sun, 27 May 2001, Harry Ohlsen wrote:
> Harry Ohlsen wrote:

> By the way, I'd be happy to accept a routine which returns the set of
> ALL subsets (ie, the power set), because I could easily code something
> to extract elements of a given size from that. 



Mine is not recursive, but it works anyway.

class Array; def power_each
  (0...2**length).each {|i|
    yield *indices(*(0...length).find_all {|j| i&(1<<j)>0 })
  }
end end

[0.618,true,42,"towel",:foo].power_each {|*x| p x}



matju