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2D heatmap¶

In [1]:

require 'gnuplotrb' include GnuplotRB include Math

init = (-PI..PI).step(0.05).to_a x = init.map { |el| [el] * init.size }.flatten y = init * init.size z = x.map.with_index { |xx, index| cos(0.5xxxx + y[index]**2) } nil

In [2]:

heatmap = Plot.new( [[x,y,z], with: 'image'], title: "Heatmap", style: 'data lines', palette: 'defined ( 0 "#000090",
1 "#000fff",
2 "#0090ff",
3 "#0fffee",
4 "#90ff70",
5 "#ffee00",
6 "#ff7000",
7 "#ee0000",
8 "#7f0000")', view: 'map', xrange: -PI..PI, yrange: -PI..PI, term: 'pngcairo' )

Out[2]:

3D heatmap¶

3D heatmap data should be prepared not the same way as simple 3D plot's. In this case data should consist of chunks:

x1 y1 z11 c11
x1 y2 z12 c12
x1 y3 z13 c13
...
x1 yN z1N c1N
                 #blank line here
x2 y1 z21 c21
x2 y2 z22 c22
...
x2 yN z2N c2N
                 #blank line here
.
.
.
                 #blank line here
xN y1 zN1 cN1
xN y2 zN2 cN2
...
xN yN zNN cNN

In [3]:

def z_function(x, y) arg = x ** 2 + y ** 2 cos(arg) * exp(-arg/5.0) end

x = init.map { |el| [el] * init.size << ' ' }.flatten y = (init + [' ']) * init.size z = x.map.with_index { |xx, index| xx.is_a?(String) ? ' ' : z_function(xx, y[index]) } color = x.map { |xx| xx.is_a?(String) ? ' ' : cos(xx) }

plot3d = Splot.new( [[x,y,z, color], title: '3D heatmap', using: '1:2:3:4', with: 'pm3d'], xrange: -PI..PI, yrange: -PI..PI, view: [49, 28, 0.8, 1.48], term: ['svg', size: [600,600]] )

Out[3]:

Gnuplot Produced by GNUPLOT 5.0 patchlevel rc2 -3 -2 -1 0 1 2 3 -3 -2 -1 0 1 2 3 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 gnuplot_plot_1 3D heatmap -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

2D heatmap (matrix example)¶

In [4]:

matrix = <<EOD 6 5 4 3 1 0 3 2 2 0 0 1 0 0 0 0 1 0 0 0 0 0 2 3 0 0 1 2 4 3 0 1 2 3 4 5 EOD File.write('heat_map_data.txt', matrix)

In [5]:

from_matrix = Splot.new( ['heat_map_data.txt', matrix: true], pm3d: 'map', palette: 'grey' )

Out[5]:

Gnuplot Produced by GNUPLOT 5.0 patchlevel rc2 gnuplot_plot_1 'heat_map_data.txt' matrix 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 6

And now interpolated one:

In [6]:

from_matrix.pm3d('map', interpolate: [8, 8])

Out[6]:

Gnuplot Produced by GNUPLOT 5.0 patchlevel rc2 gnuplot_plot_1 'heat_map_data.txt' matrix 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 6