From: Dan Zwell <dzwell@...>
Date: 2007-08-27T07:14:42+09:00
Subject: Re: sort_by { rand } not working

Lionel Bouton wrote:
> Dan Zwell wrote:
>>     for i in 0...@all.length
>>         j = i+rand(@all.length-i)
>>         @all[i], @all[j] = @all[j], @all[i]
>>     end
>>
>> The second one will be faster, but you probably shouldn't care on
>> small arrays.
>>
> 
> You could even optimize this further with 0...@all.length-1 instead of
> 0...@all.length (the last loop is a noop), but I agree, this is too much
> pain for the eyes to bother unless it becomes a real performance problem.
> 
> Sorry if this has already been said, in fact I didn't even remember this
> code on the mailing-list at all (too much traffic for me maybe).
> 
> Lionel
> 
> 

Heh, you're right about the noop, and that hasn't been said. This code 
was never on the list in this form--those 4 lines are a condensation of 
something I posted to this list from my algorithms book, and someone's 
suggestion that optimized it further (use parallel assignment instead of 
making a swap() function).

Dan