2010/6/8 Juan Matias <jmrepetti / gmail.com>:
> glen wrote:
>> Just thought I'd post a solution I came up with to finding
>> combinations (as in, permutations and combinations) of arrays. For
>> example, combining:
>>
>> [1,2] and [3,4,5]
>>
>> should return:
>>
>> [[1,3],[1,4],[1,5],[2,3],[2,4],[2,5]]
>>
>> which is easy enough. But I wanted something that combine several
>> arrays at once, ie:
>>
>> [[1,2],[3,4,5],[6,7]].combine
>> => [[1, 3, 6], [1, 3, 7], [1, 4, 6], [1, 4, 7], [1, 5, 6], [1, 5, 7],
>> [2, 3, 6], [2, 3, 7], [2, 4, 6], [2, 4, 7], [2, 5, 6], [2, 5, 7]]
>>
>
> And why not something like:
>
>  ¨Â±¬²Ý®ãïíâéîå¨Û³¬´Ý©®ãïíâéîå¨Ûµ¬¶¬·Ý©
>
> I do that with this code:
>
> class Array
>  ¨Âåæ ãïíâéîå¨ïôèåòÁòòáù>  ¨Âõø ÛÝ
>  ¨Âåìæ®åáãè äï üóåìæßåìåí>  ¨ÂôèåòÁòòáù®åáãè äï üïôèåòßåìåíü
>  ¨Âõø ¼¼ Ûóåìæßåìåí¬ïôèåòßåìåíÝ
>  ¨Âîä
>  ¨Âîä
>  ¨Âõø®íáð ûüåìåíåìåí®æìáôôåî >  ¨Âîä
> end

I'd rather do this:

module Enumerable
  def combine(enum)
    if block_given?
      each do |*a|
        enum.each do |*b|
          yield *a, *b
        end
      end
      self
    else
      enum_for(:combine, enum)
    end
  end
end

[1,2].combine([3,4]) do |*a|
  p a
end

puts "--------------"

[1,2].combine([3,4]).each do |*a|
  p a
end

puts "--------------"

[1,2].combine([3,4]).combine([5,6]) do |*a|
  p a
end

puts "--------------"

[1,2].combine([3,4]).combine([5,6]).each do |*a|
  p a
end

Kind regards

robert


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