Gnuplot.jl/docs/src/recipes.md

using Gnuplot
Gnuplot.quitall()
mkpath("assets")

empty!(Gnuplot.options.init)
push!( Gnuplot.options.init, "set term unknown")
empty!(Gnuplot.options.reset)
push!( Gnuplot.options.reset, linetypes(:Set1_5, lw=1.5, ps=1.5))
saveas(file) = save(term="pngcairo size 550,350 fontscale 0.8", output="assets/$(file).png")

Plot recipes

A plot recipe is a quicklook visualization procedure aimed at reducing the amount of repetitive code needed to generate a plot. More specifically, a recipe is a function to convert data from the "Julia world" into a form suitable to be ingested in Gnuplot.jl.

There are two kinds of recipes:

• explicit recipe: a function which is explicitly invoked by the user. It can have any name and accept any number of arguments and keywords. It is typically used when the visualization of a data type requires some extra information, beside data itself. An example is the quicklook procedure for a DataFrame object (shown below);

• implicit recipe: a function which is automatically called by Gnuplot.jl. It must extend the Gnuplot.recipe function, and accept exactly one mandatory argument. It is typically used when the visualization is completely determined by the data type itself. An example is the visualization of a Matrix{ColorTypes.RGB} object as an image.

In both cases the recipe function must return a scalar, or a vector of, PlotElements object(s), containing all the informations to create a plot, or a part of it.

The @gp or @gsp. In , and can be passed directly to @gp or @gsp.

. The fields of the PlotElements structure are:

• mid::Int:: multiplot ID;
• cmds::Vector{String}: commands to set plot properties;
• data::Vector{Dataset}: data set(s);
• plot::Vector{String}: plot specifications for each Dataset;

where Dataset is an abstract type, the actual data sets are stored in the form of either a DatasetText object (a textual representation of the data) or a DatasetBin object (a binary file). Both DatasetText and DatasetBin structures provide a number of constructors accepting several types of input data.

As anticipated, a recipe can be explicitly called by the user and the output passed to @gp or @gsp.

All arguments to @gp or @gsp (except Ints, Strings, Tuples, Array of both numbers and strings) are scanned to check if an implicit recipe exists to handle them, and in this case it is

Although a recipe provides a very efficient mean for data exploration,

Histogram recipes

Image recipes

If the orientation is not the correct one you may adjust it with the gnuplot rotate= keyword (the following example requires the TestImages package to be installed):

using TestImages
img = testimage("lighthouse");
@gp img
saveas("recipes007b") # hide

To display a gray image use with image in place of with rgbimage, e.g.:

img = testimage("walkbridge");
@gp palette(:viridis) recipe(img, "flipy rot=15deg")
saveas("recipes007c") # hide

Note that we used a custom palette (:lapaz, see Palettes and line types) and the rotation angle has been expressed in radians (-0.5pi).