Plotting graph with points given in file

First we need to have file with points

In this example I will just generate it.

In [1]:
File.open('tons_of_data', 'w') do |f|
  (1..100000).each do |x|
    xx = x/1000.0
    yy = Math.exp(Math.sin(xx))
    f.puts "#{xx} #{yy}"
  end
end
Out[1]:
1..100000

Plot points

Ok, we have file with points so lets plot them:

In [2]:
require 'gnuplotrb'
include GnuplotRB

Plot.new(['tons_of_data', title: 'Tons of data', with: 'lines'])
Out[2]:
Gnuplot Produced by GNUPLOT 5.0 patchlevel rc2 0 0.5 1 1.5 2 2.5 3 0 10 20 30 40 50 60 70 80 90 100 Tons of data Tons of data

Plotting graph with points given as array

This example will show how to plot graph from points in polar coordinate system.

In [3]:
include Math

def butterfly_point(angle)
  8 - 
    1.2 * sin(angle) +
    2 * sin(3 * angle) +
    2 * sin(5 * angle) -
    sin(7 * angle) + 
    0.8 * sin(9 * angle) -
    0.3 * sin(11 * angle) +
    4.8 * cos(2 * angle) -
    2 * cos(4 * angle) +
    0.8 * cos(13.2 * angle)
end

θ = (0.0..10*PI).step(0.01).to_a
r = θ.map { |angle| butterfly_point(angle) }

butterfly = Plot.new(
  [[θ,r], notitle: true, with: 'filledcurve', lt: {rgb: '#BCECFF'}],
  [[θ,r], title: 'Butterfly', with: 'lines', lt: {rgb: '#422515', lw: 2}],
  polar: true
)
Out[3]:
Gnuplot Produced by GNUPLOT 5.0 patchlevel rc2 15 10 5 0 5 10 15 15 10 5 0 5 10 15 0 5 10 15 gnuplot_plot_1