[R] break loop with keypress

Greg Snow 538280 at gmail.com
Wed Aug 6 03:41:03 CEST 2014

You could create a tcltk window that looks for a button click and/or
key press and when that happens change the value of a variable.  Then
in your loop you just look at the value of the same variable and break
when the value changes.

On Tue, Aug 5, 2014 at 6:13 AM, William Simpson
<william.a.simpson at gmail.com> wrote:
> This works, but it is not quite what I need:
> par(mar=rep(0,4))
> while(1)
>   {
>   img1<-matrix(runif(2500),50,50)
>   dev.hold(); image(img1,useRaster=TRUE); dev.flush()
>   img2<-matrix(runif(2500),50,50)
>   dev.hold(); image(img2,useRaster=TRUE); dev.flush()
>   }
> I would like to do this:
> while(!kbhit())
>   {
>   ...
> where kbhit() polls the keyboard, returning a non-zero integer if the
> keyboard buffer has something in it. The animation loop continues
> until a key is pressed.
> All the ways of getting user input I have seen (e.g. getGraphicsEvent)
> are not suitable because they would wait on each pass through the loop
> until the key is pressed and therefore no animation would be
> presented.
> Any ideas on how to present a continuous animation loop which is
> broken upon user input (keypress or mouse button press)? I am using
> Windows 7. Thanks very much for any help.
> Bill
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Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com

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