From: Daniel Finnie <danfinnie@...>
Date: 2007-03-12T08:06:33+09:00
Subject: Re: [QUIZ] SimFrost (#117)

A little trick you can use is setting a class method for class Torus 
that will instantiate a new Torus object:

class Torus
	def self.[](*args)
		self.new(*args)
	end
end

And then you can just do Torus[arguments here]

Dan

Robert Dober wrote:
> It doesn't get any faster
> at least I got it shorter
> 
> 649/150 > cat torus.rb
> # vim: sw=2 sts=2 nu tw=0 expandtab nowrap:
> #
> #
> 
> ICE = Class.new
> VAPOR = Class.new
> VACUUM = Class.new
> 
> 
> ###############################################################
> #
> # a small reference to Python ;)
> #
> ###############################################################
> def Torus( rows, cols, vapors, start = nil )
>  Torus_.new( rows.to_i, cols.to_i, vapors.to_f, start )
> end
> 
> class Torus_
> 
>  ###############################################################
>  #
>  #    Torus_
>  #
>  ###############################################################
>  attr_reader :lines, :columns
>  attr_reader :generation
>  attr_accessor :formatter, :name
>  def initialize rows, cols, vapors, start
>    @lines = rows
>    @columns = cols
>    @vapors = vapors
>    @generation = 0
>    if start then
>      @start = start.split("@").map{|e| e.to_i}
>    else
>      @start ||= [ rows/2, cols /2 ]
>    end
>    @nhoods = []  # we will store neighborhoods identified by
>    # their upper left corner index, odd is for even generations
>    # and even is for odd generations, which might seem odd.
>    reset_values
>    set_vapors
>  end
> 
>  def [] line, col=nil
>    return @values[line] unless col
>    @values[line][col]
>  end # def [](line, col=nil)
>  def []= line, col, val
>    @values[line][col] = val
>  end
> 
>  def each_line
>    @values.each{ |line| yield line }
>  end
> 
>  def each_nbh
>    r = c = @generation % 2
>    loop do
>      yield @nhoods[ r * @lines + c ] ||=
>          Neighborhood.new( self, r, r.succ % @lines, c, c.succ % @columns )
>      c += 2
>      r += 2 unless c < @columns
>      return unless r < @lines
>      c %= @columns
>      r %= @lines
>    end
>  end
> 
>  def start_sim
>    until no_more_vapor? do
>      tick
>      write
>    end
>  end # def start_sim
> 
>  def tick
>    puts "Simulation #{@name} generation #{@generation}:"
>    @generation += 1
>    each_nbh do
>      | nbh |
>      nbh.recalc
>    end
>  end
> 
>  private
> 
>  def no_more_vapor?
>    ! @values.any?{ |line|
>      line.any?{ |v| v == VAPOR }
>    }
>  end
> 
>  def reset_values
>    @values = Array.new(@lines){
>      Array.new(@columns){
>        VACUUM
>      }
>    }
>  end
>  def set_vapors
>    total = @lines * @columns
>    v = ( @vapors *  (total-1) ).to_i
>    x = [*0..total-2]
>    at = []
>    v.times do
>      at << x.delete_at( rand(x.size) )
>    end
>    at.each do
>      | index |
>      @values[index/@lines][index%@lines] = VAPOR
>    end
>    @values[@lines-1][@columns-1] = @values[@start.first][@start.last]
>    @values[@start.first][@start.last] = ICE
>  end # def set_vapors
> 
>  def write
>    @formatter.to_file self, "output/#{@name}.%08d" % @generation
>  end # def write
> 
> end # class Torus_
> 
> ###############################################################
> #
> #    Neighborhood is implementing a 2x2 window to any object
> #    that responds to #[]n,m and #[]=n,m,value
> #    It implements the operation of rotation.
> #
> ###############################################################
> class Neighborhood
>  include Enumerable
> 
>  # Neighborhood gives us the following indexed view to the underlying
>  # torus
>  #     +---+---+     +-----------+-----------+
>  #     | 0 | 1 |     | @top,@lft | @top,@rgt |
>  #     +---+---+     +-----------+-----------+
>  #     | 3 | 2 |     | @bot,@lft | @bot,@rgt |
>  #     +---+---+     +-----------+-----------+
>  #
> 
>  def initialize *args
>    @torus, @top, @bottom, @left, @right = *args
>    @names = [ [@top, @left], [@top, @right], [@bottom, @right],
> [@bottom, @left] ]
>  end
> 
>  def [] n
>    @torus[ *@names[n%4]  ]
>  end
>  def []= n, val
>    @torus[ *@names[n%4] ] = val
>  end
> 
>  def each
>    4.times do
>      | idx |
>      yield self[idx]
>    end
>  end
> 
>  def recalc
>    if any?{|v| v == ICE} then
>      4.times do
>        | idx |
>        self[ idx ] = ICE if self[ idx ] == VAPOR
>      end
>    else
>      rotate( rand(2) )
>    end
>  end
> 
>  def rotate dir
>    x = self[0]
>    3.times do
>      | n |
>      self[ n + 2*dir*n ] = self[ n + 1 + dir*2*n.succ ]
>    end # 3.times do
>    self[ 3 + 2 * dir ] = x
>  end # def rotate dir
> 
> end # class Neighborhood
> 650/151 > cat ppm.rb
> # vim: sw=2 sts=2 nu tw=0 expandtab nowrap:
> 
> 
> class Formatter
> 
>  @@default = { ICE => "255/255/255",
>                VAPOR => "255/0/255",
>                VACUUM => "0/0/0"
>  }
> 
>  def initialize colors={}
>    @colors = {}
>    colors.each do
>      | element, color |
>      color ||= @@default[element]
>      @colors[ element ] = " " << color.gsub("/", " ") << " "
>    end # colors.each do
>  end # def initialize colors={}
> 
>  def to_file( source, file, comment = nil )
>    comment ||= file
>    File.open( "#{file}.ppm", "w" ) do
>      | f |
>      f.puts "P3 #{source.columns} #{source.lines} 255"
>      f.puts "#"
>      f.puts "# #{comment}"
>      f.puts "#"
>      source.each_line{
>        |line|
>        count = 0
>        line.each do
>          | cell |
>          s = @colors[cell]
>          if count + s.size > 70 then
>            f.puts
>            count = 0
>          end
>          count += s.size
>          f.print s
>        end
>        f.puts unless count.zero?
>      }
>    end
>  end
> 
> end
> 651/152 > cat run.rb
> # vim: sw=2 sts=2 nu tw=0 expandtab:
> #
> require 'fileutils'
> require 'torus'
> 
> def usage msg = nil
>  $stderr.puts msg if msg
>  $stderr.puts <<-EOS
>  usage:
>  #{$0} [options] height width vapor_probability
> 
>  options and their defaults
>  -s|--start <height>/2@<width>/2      where to put the initial freezer
>                                       please use Smalltalk syntax here
>  -n|--name   run-<height>-<width>     name of the output file
>  -v|--vapor  255/0/255                rgb value for PPM
>              O                        use strings for ASCII
>  -0|--vacuum 0/0/0                    idem
>              <space>
>  -i|--ice    255/255/255              idem
>              *
>  -f|--format ppm                      ppm or ascii are supported
>                                       write your own plugins ;)
> 
>  have fun
>  EOS
>  exit -1
> end
> 
> @start = @name = nil
> @vapor = nil
> @vacuum = nil
> @ice    = nil
> @format = "ppm"
> options = { /^-f|^--format/ => :format,
>            /^-s|^--start/  => :start,
>            /^-n|^--name/   => :name,
>            /^-v|^--vapor/  => :vapor,
>            /^-0|^--vacuum/ => :vacuum,
>            /^-i|^--ice/    => :ice }
> loop do
>  break if ARGV.empty?
>  break if ARGV.first == "--"
>  break unless /^-/ === ARGV.first
>  illegal_option = true
>  options.each do
>    | opt_reg, opt_sym |
>    if opt_reg === ARGV.first then
>      usage "Missing argument for option #{ARGV}" if ARGV.length < 2
>      instance_variable_set( "@#{opt_sym}", ARGV[1] )
>      ARGV.slice!( 0, 2 )
>      illegal_option = false
>    end
>  end
>  usage ARGV.first if illegal_option
> end
> usage ARGV.join(", ") unless ARGV.size == 3
> 
> require @format rescue usage
> 
> begin
>  mkdir( "output" ) unless File.directory?( "output" )
> rescue
>  $stderr.puts 'Cannot create output directory "output"'
>  usage
> end
> 
> t = Torus( *(ARGV << @start) )
> t.name = @name || "run-#{ARGV[0..1].join("-")}"
> t.formatter = Formatter.new( ICE => @ice, VAPOR => @vapor, VACUUM => 
> @vacuum )
> t.start_sim