From: "Marcin Mielżyński" <lopexx@...>
Date: 2005-12-24T09:22:50+09:00
Subject: Re: Translate from Python to Ruby

Sam Kong wrote:
> Hi!
> 
> I am trying to get a powerset (all subsets) of a set.
> I couldn't find a code in Ruby, but I found a code in Python.
> I'm trying to convert it to Ruby but it's not done easily.
> 
> def powset(seq):
>     if seq:
>         head, tail = seq[:1], seq[1:]
>         for smaller in powset(tail):
>             yield smaller
>             yield head + smaller
>     else:
>         yield []
> 
> 1. Can somebody translate the Python code into Ruby?
> (I have difficulty in understanding the yield part)
> 

def powset seq
     unless seq.empty?
         head,tail = seq[0,1] , seq[1..-1]
         powset(tail){|smaller|
             yield smaller
             yield head + smaller
         }
     else
         yield []
     end
end

powset([1,2,5]){|e| p e}

not sure if it works for other examples

lopex