GR::Plot - A simple, matlab-style API

plot step plot3 polar scatter scatter3 stem barplot histogram polarhistogram hexbin contour contourf tricont surface trisurf wireframe volume heatmap polarheatmap shade imshow isosurface

Getting ready

you'll need the ruby-gr, numo-narray gems.

require 'gr/plot'
require 'numo/narray'

Line Plots

plot

Draw one or more line plots.

x = Numo::DFloat.linspace(0, 10, 1001)
y = Numo::NMath.sin(x)

GR.plot(x, y)

step

Draw one or more staircase or step plots.

• where: mid pre post

x = Numo::DFloat.linspace(0, 10, 51)
y = Numo::NMath.sin(x)

GR.step(x, y)

plot3

Draw one or more three-dimensional line plots.

x = Numo::DFloat.linspace(0, 30, 1000)
y = Numo::NMath.cos(x) * x
z = Numo::NMath.sin(x) * x

GR.plot3(x, y, z)

polar

Draw one or more polar plots.

angles = Numo::DFloat.linspace(0, 2 * Math::PI, 40)
radii = Numo::DFloat.linspace(0, 20, 40)

GR.polar(angles, radii)

Scatter Plots

scatter

Draw a scatter plot.

x = Numo::DFloat.linspace(0, 1, 51)
y = x - x**2
s = x * 200

GR.scatter(x, y, s)

x = Numo::DFloat.linspace(0, 1, 51)
y = x - x**2
s = Numo::DFloat.linspace(50, 300, x.size)
c = Numo::DFloat.linspace(0, 255, x.size)

GR.scatter(x, y, s, c)

scatter3

Draw a three-dimensional scatter plot.

x = 2 * Numo::DFloat.new(100).rand - 1
y = 2 * Numo::DFloat.new(100).rand - 1
z = 2 * Numo::DFloat.new(100).rand - 1
c = 999 * Numo::DFloat.new(100).rand + 1

GR.scatter3(x, y, z, c)

Stem Plots

stem

Draw a stem plot.

x = Numo::DFloat.linspace(-2, 2, 40)
y = x ** 3 + x ** 2 + x + 6

GR.stem(x, y)

Bar Plots

barplot

Draw a bar plot.

• horizontal: true false

continents = ["Africa", "America", "Asia", "Europe", "Oceania"]
population_2010 = [1044, 944, 4170, 735, 36]

GR.barplot(continents, population_2010)

Histograms

histogram

Draw a histogram of data.

• nbins: Integer

x = Numo::DFloat.new(10_000).rand_norm

GR.histogram(x)

polarhistogram

hexbin

Draw a hexagon binning plot.

• nbins: Integer

x = Numo::DFloat.new(10_000).rand_norm
y = Numo::DFloat.new(10_000).rand_norm

GR.hexbin(x, y)

Contour Plots

contour

Draw a contour plot.

• levels: Integer

x = 8 * Numo::DFloat.new(60).rand - 4
y = 8 * Numo::DFloat.new(60).rand - 4
z = Numo::NMath.sin(x) + Numo::NMath.cos(y)

GR.contour(x, y, z)

_x = Numo::DFloat.linspace(-2, 2, 40)
_y = Numo::DFloat.linspace(0, Math::PI, 20)
x = (_x.expand_dims(0) * Numo::DFloat.ones(_y.size, 1)).flatten
y = (_y.expand_dims(1) * Numo::DFloat.ones(1, _x.size)).flatten
z = (Numo::NMath.sin(x) + Numo::NMath.cos(y)).flatten

GR.contour(x, y, z)

contourf

Draw a filled contour plot.

• levels: Integer

x = 8 * Numo::DFloat.new(100).rand - 4
y = 8 * Numo::DFloat.new(100).rand - 4
z = Numo::NMath.sin(x) + Numo::NMath.cos(y)

GR.contourf(x, y, z)

tricont

Draw a triangular contour plot.

x = 8 * Numo::DFloat.new(300).rand - 4
y = 8 * Numo::DFloat.new(300).rand - 4
z = Numo::NMath.sin(x) + Numo::NMath.cos(y)

GR.tricont(x, y, z)

Surface Plots

surface

Draw a three-dimensional surface plot.

• accelerate true false

x = 8 * Numo::DFloat.new(100).rand - 4
y = 8 * Numo::DFloat.new(100).rand - 4
z = Numo::NMath.sin(x) + Numo::NMath.cos(y)

GR.surface(x, y, z)

trisurf

Draw a triangular surface plot.

x = 8 * Numo::DFloat.new(100).rand - 4
y = 8 * Numo::DFloat.new(100).rand - 4
z = Numo::NMath.sin(x) + Numo::NMath.cos(y)

GR.trisurf(x, y, z)

wireframe

Draw a three-dimensional wireframe plot.

x = 8 * Numo::DFloat.new(1000).rand - 4
y = 8 * Numo::DFloat.new(1000).rand - 4
z = Numo::NMath.sin(x) + Numo::NMath.cos(y)

GR.wireframe(x, y, z)

Volume Rendering

volume

Draw a the three-dimensional array v, using volume rendering.

• algorithm: 0 1 2

z = Numo::DFloat.new(50, 50, 50).rand_norm

GR.volume(z)

Heatmaps

heatmap

Draw a heatmap.

x = Numo::DFloat.linspace(-2, 2, 40)
y = Numo::DFloat.linspace(0, Math::PI, 20)
z = Numo::NMath.sin(x).expand_dims(0).transpose + Numo::NMath.cos(y)

GR.heatmap(z)

polarheatmap

Draw a polar heatmap.

angle = Numo::DFloat.linspace(0, 2*Math::PI, 40)
radius = Numo::DFloat.linspace(0, 10, 20)
z = Numo::NMath.sin(angle.expand_dims(0).transpose) * Numo::NMath.cos(radius)

GR.polarheatmap(z)

shade

Draw a point- or line-based heatmap.

• xform 0 1 2 3 4 5

n = 1_000_000
x = Numo::DFloat.new(n).rand_norm
y = Numo::DFloat.new(n).rand_norm

GR.shade(x, y)

Images

imshow

Draw an image.

x = Numo::DFloat.linspace(-1, 1, 20)
y = Numo::DFloat.linspace(0, Math::PI, 30)
z = Numo::NMath.sin(x).expand_dims(0).transpose + Numo::NMath.cos(y)

GR.imshow(z)

Isosurfaces

isosurface

Draw an isosurface.

require 'gr3'
s = Numo::DFloat.linspace(-0.6, 0.6, 50)
v = 1 - ((s**2 +  (s**2).expand_dims(0).transpose).expand_dims(2) + s.reshape(1, 1, true)**2)**0.5

GR.isosurface(v)