From: Stephen Waits <steve@...>
Date: 2005-12-07T05:04:13+09:00
Subject: Re: Shuffling an array, sort_by{rand}'s bias (was Re: need some Ruby

Stephen Waits wrote:
> I forgot to deal with collisions in the hash!   :(

Here's another shot.. still faster than sort_by{rand} on my system, and 
now should be unbiased:

   def shuffle3
     h = Hash.new
     self.each do |v|
       k = rand(1000000000) until !h.has_key?(k)
       h[k] = v
     end
   end

shuffle3 (10000)  3.625000   0.016000   3.641000 (  3.656000)
sort_by (10000)   5.250000   0.000000   5.250000 (  5.312000)

--Steve