PyPlot doesn't work with the plot pane

[davidanthoff]

[davidanthoff]

@stevengj I'm trying to figure out why something like plot(randn(10), randn(10)) doesn't just show up in the plot pane in VS Code when entered in the integrated REPL.

The plot does show up in the plot pane when I execute gcf(), that returns an instance of PyPlot.Figure. But the call to just plot seems to return

1-element Array{PyCall.PyObject,1}:
 PyObject <matplotlib.lines.Line2D object at 0x0000000024CCFBA8>

which doesn't hook into the standard multimedia display system, as far as I can tell.

Is that just how it is, or is there some way that we could get a simple call to plot to show something in the plot pane?

[davidanthoff]

I'm also moving this to v0.9.0 because there is a workaround for now: just call gcf().

[stevengj]

PyPlot functions don't return a displayable object, they work by side effects. If you want to return a displayable figure, you can do withfig(figure()) do .... end or you can return gcf().

In IJulia, PyPlot pushes some hooks to display plots after a cell executes. I don't know if it is possible to do something similar with vscode?

[davidanthoff]

We just run the normal julia REPL inside VS Code and push our display backend onto the multimedia stack, that is really all we do. So unless there is some generic solution for the basic julia REPL I think we shouldn't really add anything beyond that.

I think this sounds just like by design then. Thanks for clarifying!

[stevengj]

One alternative is to have PyPlot call redisplay(fig) as a side-effect of each plotting function, and have your display backend use redisplay to push the figure onto a queue to display. PyPlot used to do this, in fact, but was really fragile because it involved monkey-patching matplotlib, and it was difficult to get it to work properly with Interact as well.

[davidanthoff]

Ah, I'll have to figure out redisplay and how that would map with the approach we are using, thanks for the pointer.