From: Bill Kelly <billk@...>
Date: 2005-12-07T01:12:14+09:00
Subject: Re: Shuffling an array, sort_by{rand}'s bias (was Re: need some Ruby

Hi,

From: "Uwe Schmitt" <schmitt@num.uni-sb.de>
> || 
> || On Tue, Dec 06, 2005 at 07:32:34PM +0900, Uwe Schmitt wrote:
> || > Is there a shorter or more elegant way to do this 
> || > 'decorate-sort-undecorate' in ruby ?
> || 
> || arr.sort_by{rand}
> 
> that is not equivalent to my solution.
> the python equivalent to yours is
> 
>   arr.sort(key = lambda x: random())

No, Array#sort_by does the 'decorate-sort-undecorate', aka.
Schwartzian Transform.

I don't read Python very well, but I think the ruby equivalent
to 'arr.sort(key = lambda x: random())' might be:

  arr.sort { rand <=> rand }

But that is different from arr.sort_by {rand}


Regards,

Bill