From: Ralf Mueller <ralf.mueller@...>
Date: 2012-04-12T22:08:31+09:00
Subject: Re: ruby v.1.8.6. Expand array class, make combinations

On 04/12/2012 10:10 AM, Ronnie Aa wrote:
> Hi,
>
> I'm using Sketchups' ruby; its version: 1.8.6. Sketchup is a 3D design
> program which has as ruby built in to perform all kinds of operations on
> geometry.I'm not able to use higher versions of ruby.
>
> My question:
>
>
>
> This is what I want to accomplish:
>
> ["a","b","c","d"].permutation(2)
>
> ==>  [ [a,b],[a,c],[a,d],[b,c],[b,d],[c,d] ]
> but it's not available for me
>
>
>
> I also found:
>
> http://permutation.rubyforge.org/. I succeeded to install the gem,
> but I couldn't accomplish the above.
>
>
>
>
> So I've created my own method:
>
> class Array
>    def comby  ## Make al unique combinations of 2 elements
>
>       posmax = (length - 1)
>
>
>       newarr = []
>
>
>
>      for n in 0.. posmax
>        for m in 0.. posmax
>          i1 = self[n]
>          i2 = self[m]
>          if  newarr.include? ([i2,i1])
>             # newarr.push('X')
>          elsif i1 == i2
>              # newarr.push('X')
>          else
>             newarr.push([i1,i2])
>          end
>        end
>      end
>      puts  newarr[0..14]
>                  ==>  [ [a,b],[a,c],[a,d],[b,c],[b,d],[c,d] ]
>
>    end
>
> end
>
> //program
>
> mm = ["a","b","c","d"]
>
> mm.comby
>
> //
>
>
>
>
> It puts the right values, but what I can't use newarr ( tried also
> @newarr)
> in my program.
>
> What would like to see:
>
> mm = ["a","b","c","d"]
> aa = mm.comby
> puts aa
> ==>  [ [a,b],[a,c],[a,d],[b,c],[b,d],[c,d] ]
>
> What can I do??
>
>
> Thanks!
>
What about ruby facets: 
http://rubyworks.github.com/rubyfaux/?doc=http://rubyworks.github.com/facets/docs/facets-2.9.3/core.json#api-class-Array/api-method-Array-h-combination 

There is a combination method for the Array class. does it fit your needs?

ralf