From: "Hal E. Fulton" <hal9000@...>
Date: 2003-03-29T20:21:11+09:00
Subject: Re: Weighted random selection -- how would you do this?

----- Original Message ----- 
From: "Tom Payne" <google@tompayne.org>
Newsgroups: comp.lang.ruby
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Saturday, March 29, 2003 4:05 AM
Subject: Re: Weighted random selection -- how would you do this?


> It's not exactly what you want (but there are good reasons for it
> being different), but here's the code I've been using for ages:
> 
> module WeightedRand
> 
>   def select
>     p = rand
>     each do |prob, value|
>       return value if p < prob
>       p -= prob
>     end
>     nil
>   end
> 
> end
> 
> a = [[0.5, :heads], [0.5, :tails]].extend(WeightedRand)
> 5.times { puts(a.select) }

Again, interesting. But I keep thinking about Phil's
comment about order.

Is there a consequence to the fact that you are 
iterating through a list in order? Might the
results be "clustered" in some way?

I'm not much on probability and stats; and I've
been up a long time. :)

Hal