From: "David A. Black" <dblack@...>
Date: 2008-07-04T01:15:50+09:00
Subject: Re: pseudo-randomize an array in a consistent order

Hi --

On Fri, 4 Jul 2008, James Gray wrote:

> On Jul 3, 2008, at 11:08 AM, James Gray wrote:
>
>> On Jul 3, 2008, at 11:04 AM, Robert Dober wrote:
>> 
>>> a.sort{ rand }
>> 
>> Don't do that:
>> 
>> >> a = (1..5).to_a
>> => [1, 2, 3, 4, 5]
>> >> a.sort { rand }
>> => [5, 3, 1, 4, 2]
>> >> a.sort { rand }
>> => [5, 3, 1, 4, 2]
>> >> a.sort { rand }
>> => [5, 3, 1, 4, 2]
>
> Oh, you meant to show this behavior.  My bad.

It's not really even pseudo-random, though -- it's just what you get
if you always say that a <=> b is > 0. [1,2,3,4,5].sort { 1 } does the
same thing. So every 5-element array will shuffle the same way, which
I don't think is what the OP wanted.


David

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