[R] 'pausing' in R

[Prof Brian D Ripley]

On Wed, 21 Jun 2000, Gardar Johannesson wrote:

> 
> 
> I have this 'odd' problem; I need to let R pause, for a given time, before
> starting next iteration in a loop.  I'm using the following to do this
> task, but feel a little bit guilty because I'm using as much CPU time as I
> can get while pausing:
> 
> while(keepGoing) {
>   t.end <- proc.time()[3] + 5  ## the time this loop should end at
> 
>   [block of R commands]
> 	
>   while(proc.time()[3] < t.end) {}
> }
> 
> This guaranty, at least, 5 second evaluation time for each loop in the
> above case.
> 
> Can I delay the loop more efficiently, that is, not using as much CPU time
> as in the above case?

Try

system("sleep 5")

That will use essentially no CPU time, but it will block the process.
That stops re-sizing graphics windows for examples, but on Unix
is not too serious.  I am not sure of the effect on the GNOME console,
nor what happens if tcltk is running.

If anyone wants to do this on Windows. take a look at the xgobi
function in the current version of the XGobi package, as that package
has an equivalent in C (that does handle events during the pause).

We do plan to have a version of this for all platforms in due course.


-- 
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)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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