[Rd] interrupting R from a GUI
Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri Jan 16 08:07:25 CET 2009
On Fri, 16 Jan 2009, Felix Andrews wrote:
> I am looking for a way to interrupt R from a callback: specifically,
> to interrupt plotting (typically on a cairoDevice, but would be good
> if it worked with other devices too). Of course, one can interrupt R
> nicely from the console with Ctrl-C (or Esc in Rgui), but I need to do
> it from a GUI. Callbacks run in a new thread, so obviously stop() etc
> will not work. I tried to look into how Rgui does it...
Actually no, Rgui does not use that code (but Rterm does).
> ?...but it is beyond me.
In detail this is OS-specific, but what the front-ends do is to set a
flag or send a signal to R: look e.g. at rterm.c:
static void my_onintr(int nSig)
UserBreak = 1;
or onintr in errors.c (which is called when UserBreak = 1, from the
ain thread). In due course R_interrupts_pending gets set and then at
an appropriate spot R stops and unwinds the currrent evaluations.
The relevant Windows code is even in 'Writing R Extensions'.
So depending on your OS you can raise a signal or set a flag. You can
raise a signal on Windows too, so 'raise' is the most portable
solution -- but beware that threading models differ.
> Alternatively, might there be a way to tell the cairoDevice widget to
> stop drawing, somehow?
Why not ask its author?
> Any help would be appreciated.
> Felix Andrews / 安福立
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Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/‾ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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