From: Daniel Sheppard <daniels@...>
Date: 2006-02-03T10:16:56+09:00
Subject: Re: neuroimage software - scientific computing and visualization

> So are you saying that if you have an array like:
>   a = ['d', 'b', 'a', 'c', 'e']
> You would like to get something like:
>   a.sort_index #=> [2, 1, 3, 0, 4]
> 
> If that's the case, then I'm sure it's doable.  No built-in 
> method that I'm 
> aware of, but you could easily create one.

For example:

class Array
  def sort_index
    (0...size).sort_by {|i| self[i]}
  end
end

%w{d b a c e}.sort_index
=> [2, 1, 3, 0, 4]