3D plot

With Gordon James Miller’s rgplot package you can use gnuplot from within Ruby.  This example shows how you can use gnuplot for displaying a 3D plot of the values in a two-dimensional array.

See also

• 2D plot
• http://www.gnuplot.info/
• http://rgplot.rubyforge.org/

#!/usr/bin/env ruby
require 'hornetseye'
require 'gnuplot'
include  Hornetseye
class Sequence_
  def to_gsplot
    retval = ""
    for j in 0...shape[1]
      for i in 0...shape[0]
        retval += " #{self[i,j]}"
      end
      retval += "\n"
    end
    retval += "\n"
    retval
  end
  def plot
    Gnuplot.open do |gp|
      Gnuplot::SPlot.new( gp ) do |plot|
        plot.pm3d
        plot.hidden3d
        plot.palette 'defined (   0 "black", 51 "blue", 102 "green", ' +
                               '153 "yellow", 204 "red", 255 "white" )'
        plot.data << Gnuplot::DataSet.new( self ) do |ds|
          ds.with = 'lines'
          ds.matrix = true
        end
      end
    end
  end
end
s = Sequence.sfloat( 60 ).indgen!( 0.5 - 60 / 2 ) / Math::PI
sinc = MultiArray.tensor( 2 ) do |i,j|
  r = Math.hypot s[i], s[j]
  Math.sin( r ) / r
end
sinc.plot