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
>> =3D> [[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:
>
> =A0[1,2].combine([3,4]).combine([5,6,7])
>
> I do that with this code:
>
> class Array
> =A0def combine(otherArray)
> =A0 =A0aux =3D []
> =A0 =A0self.each do |self_elem|
> =A0 =A0 =A0otherArray.each do |other_elem|
> =A0 =A0 =A0 =A0aux << [self_elem,other_elem]
> =A0 =A0 =A0end
> =A0 =A0end
> =A0 =A0aux.map {|elem| elem.flatten }
> =A0end
> 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

--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/