From: Stefano Crocco <stefano.crocco@...>
Date: 2008-06-01T02:42:22+09:00
Subject: Re: how to sort a multi-elements array

On Saturday 31 May 2008, Erwin wrote:
> I know how to sort an array with 2 elements... that's the only example
> I could fin on Array#sort...
> but what if ... I need to sort an array like this one :
>
> anArray = [ [1, "joe", 4], [2, "arthur", 2], [5, "william", 3], [16,
> "bob", 1], [20, "ernesto", 17], [27, "julia", 1], [28, "barbara", 2] ]
>
> sorting on third-element (highest ranking) , and second-element
> (nickname)
>
> aSortedArray = [ [20, "ernesto", 17], [1, "joe", 4], 5, "william", 3],
> [2, "arthur", 2],  [28, "barbara", 2], [16, "bob", 1] ]
>
> any doc link where this is explained ?
>
> thanks a lot for your tip

You can do this:

aSortedArray = anArray.sort do |a, b|
   if a[2] == b[2] then a[1] <=> b[1]
   else a[2] <=> b[2]
   end
end

If the third element of the two subarrays are equal, then the block returns 
the result of the comparison of the second elements (using <=>), otherwise it 
returns the result of the comparison of the third elements, again using <=>.

I hope this helps

Stefano