Multiple plots - red-data-tools/GR.rb GitHub Wiki
Mutiple line plots
x = Numo::DFloat.linspace(0, 10, 1001)
y1 = Numo::NMath.sin(x)
y2 = Numo::NMath.cos(x)
GR.plot([x, y1], [x, y2])

x = Numo::DFloat.linspace(0, 10, 101)
y1 = Numo::NMath.sin(x)
y2 = Numo::NMath.cos(x)
GR.plot([x, y1, spec: 'o'], [x, y2, spec: 'g+'])

GR.plot(
[x, y1, 'go'], [x, y2, 'r*'],
title: "Multiple plot example",
xlabel: "x",
ylabel: "y",
ylim: [-1.2, 1.2],
labels: ["sin(x)", "cos(x)"],
location: 11,
figsize: [8,4]
)

known issue
https://github.com/red-data-tools/GR.rb/issues/27