From: "William James" <>
Date: 2009-12-18T03:40:34+09:00
Subject: Re: Unique combination of values from arrays

Milo Thurston wrote:

> Here's a problem for which I can't see an obvious solution, and hope
> someone might have some suggestions.
> 
> I have several arrays, each with a variety of text values in them. I
> need to construct some strings consisting of each unique combination
> of the arrays in order. Here's a very simple example:
> 
> first_array  = ['one','two']
> second_array = ['three','four']
> 
> required output:
> 
> one,three
> one,four
> two,three
> two,four
> 
> There are more arrays than that and more entries in each array, but
> that's the basic idea. Any advice welcome - thanks!

one = [1,2]
two = [3,4]
three = [5,6,7]
a = [one, two, three]

def combi ary_of_ary
  ary_of_ary.inject([[]]){|old,lst|
    lst.inject([]){|new,e| new + old.map{|c| c + [ e ] }}}
end

puts combi( a ).map{|x| x.join ','}.sort


=== output ===
1,3,5
1,3,6
1,3,7
1,4,5
1,4,6
1,4,7
2,3,5
2,3,6
2,3,7
2,4,5
2,4,6
2,4,7

--