From: Dan Zwell <dzwell@...>
Date: 2007-08-28T02:28:25+09:00
Subject: Re: sort_by { rand } not working

thomas.macklin@gmail.com wrote:
> If you don't mind removing duplicates, Sets are non-ordered, so you
> could do
> s = Set.new
> @all.each do |e| s.add(e) end
> 
> That will be non-ordered, but duplicates will get stripped.
> 
> Tom
> 
> 
> 

Non-ordered isn't the same as randomized. Sets most certainly are 
ordered, we (the non-ruby-core-developers) just don't know how. The 
point is that they aren't guaranteed to be random. Try running the above 
code and see--it results in the same ordering each time, regardless of 
the order in which the elements are added. For some data sets, it will 
probably appear more random than others.

Dan