Adding global title to Plots.jl subplots

Question

I would like to add a global title to a group of subplots using Plots.jl.

Ideally, I'd do something like:

using Plots
pyplot()
plot(rand(10,2), plot_title="Main title", title=["A" "B"], layout=2)

but, as per the Plots.jl documentation, the plot_title attribute is not yet implemented:

Title for the whole plot (not the subplots) (Note: Not currently implemented)

In the meanwhile, is there any way around it?

I'm currently using the pyplot backend, but I'm not especially tied to it.

Answer 1

This is a bit of a hack, but should be agnostic to the backend. Basically create a new plot where the only contents are the title you want, and then add it on top using layout. Here is an example using the GR backend:

# create a transparent scatter plot with an 'annotation' that will become title
y = ones(3) 
title = Plots.scatter(y, marker=0,markeralpha=0, annotations=(2, y[2], Plots.text("This is title")),axis=false, grid=false, leg=false,size=(200,100))

# combine the 'title' plot with your real plots
Plots.plot(
    title,
    Plots.plot(rand(100,4), layout = 4),
    layout=grid(2,1,heights=[0.1,0.9])
)

Produces:

Answer 2

More recent versions of Plots.jl support the plot_title attribute, which provides a title for the whole plot. This can be combined with individual titles of individual plots.

using Plots   

layout = @layout [a{0.66w} b{0.33w}]
LHS = heatmap(rand(100, 100), title="Title for just the heatmap")
RHS = plot(1:100, 1:100, title="Only the line")
plot(LHS, RHS, plot_title="Overall title of the plot")

Alternatively, you can set the title for an existing plot directly.

p = plot(LHS, RHS)
p[:plot_title] = "Overall title of the plot"
plot(p)