From: "Eric I." <rubytraining@...>
Date: 2008-07-04T03:56:54+09:00
Subject: Re: pseudo-randomize an array in a consistent order

On Jul 3, 11:57 am, Max Williams <toastkid.willi...@gmail.com> wrote:
> This is what i did in the meantime since asking (I monkey-patched
> Array):
>
> class Array
>
>   def randomize(seed=nil)
>    srand(seed) if seed
>    self.sort{|a,b| rand <=> rand }
>   end
>
>   def randomize!(seed=nil)
>    srand(seed) if seed
>    self.sort!{|a,b| rand <=> rand }
>   end
>
> end


Hi Max,

How about a very small change:

class Array
  def randomize(seed=nil)
    srand(seed) if seed
    sort_by { rand }
    srand  # re-seed random number generator
  end

  def randomize!(seed=nil)
    replace(randomize(seed))
  end
end

Because the seed used to generate random values (via Kernel#rand) is
global, if you switch it back, you'll (likely) affect random numbers
across your entire Ruby instance.  I don't know if this will have any
effect on your current project, but should you ever integrate this
technique on another project, it could cause a problem.

Eric

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