From: Ronnie Aa <lists@...>
Date: 2012-04-12T17:10:10+09:00
Subject: ruby v.1.8.6. Expand array class, make combinations

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!

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