gnuplot gem heatmap test

plot.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

#
# plot-3d-ipa.rb
#
# Author:
#   Rintaro Okamura
#
# Requires ruby-netcdf
#   https://www.gfd-dennou.org/arch/ruby/products/ruby-netcdf/
#
# Usage:
#   $ ruby plot-3d-ipa.rb ncfile1 ncfile2 x y output
#
# Changelog:
#   20160125 - First version
#


require 'narray'
require 'gnuplot'
require 'optparse'

# https://github.com/rdp/ruby_gnuplot/blob/master/lib/gnuplot.rb#L358
class SPlot < Gnuplot::Plot

  def initialize (io = nil, cmd = "splot")
    @cmd = cmd
    @settings = []
    @arbitrary_lines = []
    @data = []
    @styles = []
    yield self if block_given?
    $stderr.puts "writing this to gnuplot:\n" + to_gsplot + "\n" if $VERBOSE

    if io
      io << to_gsplot
      io << store_datasets
    end
  end

  def to_gsplot (io = "")
    @settings.each do |setting|
      io << setting.map(&:to_s).join(" ") << "\n"
    end
    @styles.each{|s| io << s.to_s << "\n"}
    @arbitrary_lines.each{|line| io << line << "\n" }

    io
  end

  def store_datasets (io = "")
    if @data.size > 0
      io << @cmd << " " << @data.collect { |e| e.plot_args }.join(", ")
      io << "\n"

      v = @data.collect { |ds| ds.to_gsplot }
      io << v.compact.join("e\n")
    end
  end
end

class Array
  def to_gsplot
    f = ""

    if ( self[0].kind_of? Array ) then
      x = self[0]
      y = self[1]
      d = self[2]

      x.each_with_index do |xv, i|
        y.each_with_index do |yv, j|
          f << [ xv, yv, d[i][j] ].join(" ") << "\n"
        end
        f << "\n"
      end
    elsif ( self[0].kind_of? Numeric ) then
      self.length.times do |i| f << "#{self[i]}\n" end
    else
      self[0].zip( *self[1..-1] ).to_gsplot
    end

    f
  end
end

nx=5
ny=5

outfile="test.png"

# generate index
x = [*1..nx]
y = [*1..ny]

cot_2d = NArray.sfloat(nx, ny)

cot_2d.indgen(1)

puts cot_2d.to_a

cot_2d_arr = cot_2d[true,true].to_a.transpose

maxval = cot_2d_arr.flatten.max

Gnuplot.open do |gp|
  SPlot.new(gp) do |plot|
    case outfile
    when /^none$/
      plot.terminal 'x11'
    when /\.tex$/
      plot.terminal "tikz"
      plot.output File.expand_path(outfile.gsub(/\.tex$/, '_cot.tex'))
    when /\.pdf$/
      plot.terminal "pdf font 'Helvetica,7'"
      plot.output File.expand_path(outfile.gsub(/\.pdf$/, '_cot.pdf'))
    when /\.png$/
      plot.terminal "pngcairo"
      plot.output File.expand_path(outfile.gsub(/\.png$/, '_cot.png'))
    else
      STDERR.puts "Error: unknown filetype"
      exit
    end

    plot.set "termoption noenhanced"

    plot.title "Cloud Optical Thickness"
    plot.xlabel "x"
    plot.ylabel "y"
    plot.cblabel "Optical Thickness"

    plot.set "view map"
    plot.set "size square"

    plot.xrange "[0.5:#{nx}.5]"
    plot.yrange "[0.5:#{ny}.5]"

    plot.cbrange "[0:#{maxval}]"

    plot.set "key off"

    plot.set "palette defined ( 0 0 0 0, 1 1 1 1 )"

    plot.data <<
    Gnuplot::DataSet.new([x, y, cot_2d_arr]) do |ds|
      ds.with = "image"
    end

  end
end