From: Ilmari Heikkinen <kig@...>
Date: 2004-12-16T03:31:08+09:00
Subject: Re: [ANN] rand.rb 0.9: Random access methods for Enumerables


On 15.12.2004, at 19:05, Neil Spring wrote:
>   def shuffle!
>     each_index {|j| i = rand(size-j); self[j], self[j+i] = self[j+i], 
> self[j]}
>     self
>   end
>
> I would not rely on sort to do the right thing, and it is less 
> efficient than necessary.  I use the second shuffle code extensively 
> in my code which deals with shuffling lots and lots of elements.  
> Presumably the second is O(n) where the sort based scheme is at best 
> O(n log n).  A little googling suggests this is the "Fisher-Yates 
> shuffle."

Thank you, changing #shuffle! to that and #shuffle to dup.shuffle!

-Ilmari