Re: How to Generate Weighted Random Numbers

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From	Robert Klemme <shortcutter@googlemail.com>
Newsgroups	comp.lang.ruby
Subject	Re: How to Generate Weighted Random Numbers
Date	Thu, 5 May 2016 19:08:39 +0200
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On 05.05.2016 18:17, Jesus Castello wrote:

> I wrote an article about how you can generate weighted random
> numbers  with some simple algorithms. I think you will like it :)
>
> Read it here:
> http://www.blackbytes.info/2016/05/weighted-random-numbers/
>
> Let me know what you think!

Unfortunately indentation was screwed up in the comment.  So here it 
comes again:

Here’s my solution:

weights = {cats: 5, dogs: 1}.inject([]) {|a, (it, w)|
   a << [it, w + (a.last.last rescue 0)]}

p weights

counts = Hash.new {|h, it| h[it] = 0}

10000.times do
   r = rand(weights.last.last)
   it = weights.find {|it, w| r < w}
   p r, it
   counts[it] += 1
end

p counts

Advantage: you have to do less arithmetic during picking of the value 
because that is done in the preparation step.

Cheers

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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How to Generate Weighted Random Numbers Jesus Castello <matugm@gmail.com> - 2016-05-05 09:17 -0700
  Re: How to Generate Weighted Random Numbers Robert Klemme <shortcutter@googlemail.com> - 2016-05-05 19:08 +0200

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