Redirect all plot output to specific file

Question

I want to automatically redirect all plotting to a file (reason: see below). Is there a non-hacky way of accomplishing that?

Lacking that, I’m actually not afraid of overriding the built-in functions, I’m that desperate. The easiest way I can think of is to hook into the fundamental plot-window creation function and calling pdf(…) and then hooking into the plot-finalising function and calling dev.off() there.

But what are these functions? Through debugging I’ve tentatively identified dev.hold and dev.flush – but is this actually true universally? Can I hook into those functions? I cannot override them with R.utils’ reassignInNamespace because they are locked, and just putting same-name functions into the global namespace doesn’t work (they’re ignored by plot).

---

So, why would I want to do something so horrible?

Because I’m working on a remote server and despite my best attempts, and long debugging sessions with our systems support, I cannot get X11 forwarding to work reliably. Not being able to preview a plot is making my workflow horribly inefficient. I’ve given up on trying to get X11 to work so now I’m creating PDFs in my public_html folder and just refresh the browser.

This works quite well – except that it‘s really annoying and quite time-consuming to always have to surround your plotting function calls with pdf(…) … dev.off(), especially in interactive sessions where you want to quickly create a plot while in a meeting with collaborators. In fact, it’s really annoying and they (understandably) haven’t got the patience for that.

For now I’m helping myself with the following function definition:

preview <- function (.expr, ...) {
    on.exit(dev.off())
    pdf(PREVIEW_FILE_NAME, ...)
    eval(substitute(.expr))
}

Which is used like this:

preview(plot(1:100, rnorm(100) * 1:100))

That works a-ok. But this workflow is a real bottleneck in meetings, and I’d like to get rid of the preview call to streamline it as much as possible.

Any chance at all?

Answer 1

If you set options(device=FUN) then the graphics device function FUN becomes the new default graphics device that will be opened when a plot is created and device is not already opened.

So, one option would be to write a function that calls pdf or png or other graphics device with the filename and options that you want (probably onefile=FALSE in pdf), then set this function as the default in the options. You may need to use one of dev.off, plot.new, or frame to finalize the current plot (R does not finalize until you close the device or go to a new plot in case you want to add anything to the current plot).

If you will never add to a plot then you could use addTaskCallback to call dev.off automatically for you. There may be other hooks that you could use to finalize as well.