From: Robert Dober <robert.dober@...>
Date: 2007-03-12T05:18:24+09:00
Subject: Re: [QUIZ] SimFrost (#117)

On 3/11/07, Christoffer Lern� <lerno@dragonascendant.com> wrote:
> It's interesting that it looks like everyone populated their grid
no Sir not me ;) but my code is longer and I wonder if it was worth
it, now that I have looked at the outcomes of 55,60,65,70,75 and 80%
vapor
> using a randomizer for each position in the grid.
>
> This is is obviously fast, but for small grids (and low percentages),
> the percentage of actual generated vapour particles may be off by
> quite a bit.

>
> For a 10x10 grid and 10% vapour, the amount of particles typically
> range between 5 and 15, which in turn makes the finished frost look
> very different from run to run.
>
> I was thinking of ways to solve this. Obviously trying to randomly
> put vapour particles into an array - and retry if it already
> cointains vapur - is not ideal...
Almost interminable, I was using it too, look at Torus_#set_vapors in
my solution
>
> My best trick is this one:
>
> require 'enumerator'
> percentage = 30
> width = 30
> height = 20
> vapour = width * height * percentage / 100
> vacuum = width * height - vapour
> grid = []
> (Array.new(vacuum, ' ') + Array.new(vapour, '.')).sort_by
> { rand }.each_slice(width) { |s| grid << s }
>
> This gives us a grid that is guaranteed to have the correct initial
> proportion of vapour.
>
> Anyone else with a more elegant solution to the problem?
>
>
> Christoffer
>
>
>

Robert
-- 
We have not succeeded in answering all of our questions.
In fact, in some ways, we are more confused than ever.
But we feel we are confused on a higher level and about more important things.
-Anonymous