Accessing backend specific functionality with Julia Plots

Question

Plots is simple and powerful but sometimes I would like to have a little bit more control over individual elements of the plot to fine-tune its appearance.

Is it possible to update the plot object of the backend directly?

E.g., for the default pyplot backend, I tried

using Plots
p = plot(sin)
p.o[:axes][1][:xaxis][:set_ticks_position]("top")

but the plot does not change. Calling p.o[:show]() afterwards does not help, either.

In other words: Is there a way to use the PyPlot interface for a plot that was initially created with Plots?

Edit:

The changes to the PyPlot object become visible (also in the gui) when saving the figure:

using Plots
using PyPlot
p = Plots.plot(sin, top_margin=1cm)
gui() # not needed when using the REPL
gca()[:xaxis][:set_ticks_position]("top")
PyPlot.savefig("test.png")

Here, I used p.o[:axes][1] == gca(). One has to set top_margin=1cm because the plot area is not adjusted automatically (for my actual fine-tuning, this doesn't matter).

This also works for subsequent updates as long as only the PyPlot interface is used. E.g., after the following commands, the plot will have a red right border in addition to labels at the top:

gca()[:spines]["right"][:set_color]("red")
PyPlot.savefig("test.png")

However, when a Plots command like plot!(xlabel="foo") is used, all previous changes made with PyPlot are overwritten (which is not suprising).

The remaining question is how to update the gui interactively without having to call PyPlot.savefig explicitly.

Answer 1

No - the plot is a Plots object, not a PyPlot object. In your specific example you can do plot(sin, xmirror = true).

Answer 2

I'm trying to do the same but didn't find a solution to update an existing plot. But here is a partial answer: you can query information from the PyPlot axes object

julia> Plots.plot(sin, 1:4)

julia> Plots.PyPlot.plt[:xlim]()
(1.0,4.0)

julia> Plots.plot(sin, 20:24)

julia> ax = Plots.PyPlot.plt[:xlim]()
(20.0,24.0)

and it gets updated.