R help - Aug 2009 - jpeg device loop problem

Dear R gurus,
Trying to loop a graphing function and output a jpeg file each loop. It
works fine for a single run (ie. not looping) but when I loop the output is
nothing but white space. 
Here is my code, somewhat abridged:

{
<rest of loop>
  jpeg(filename=<"name for this loop.jpeg">)
  xyplot(AbvBioAnnProd~Year|factor(Plot), type = c("b",
"r"), pch 16,data=dd.mono.i,main=<"name for this
loop">)
  dev.off()
}

Is there a problem with my device settings? As I noted above it works once
but not when repeated. I'm afraid I do not understand the implementation of
the devices well enough to know. Is there a good graphics tutorial you could
point me to?

Thanks!


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On Aug 24, 2009, at 8:19 PM, AllenL wrote:
>
> Dear R gurus,
> Trying to loop a graphing function and output a jpeg file each loop.  
> It
> works fine for a single run (ie. not looping) but when I loop the  
> output is
> nothing but white space.
> Here is my code, somewhat abridged:
>
> {
> <rest of loop>
>  jpeg(filename=<"name for this loop.jpeg">)
You will need to be sure that you are not overwriting. What is the  
code that sequences through the names?
>  xyplot(AbvBioAnnProd~Year|factor(Plot), type = c("b",
"r"), pch > 16,data=dd.mono.i,main=<"name for this
loop">)
Inside loops, you generally need to print() lattice objects.
>  dev.off()
> }
>
> Is there a problem with my device settings? As I noted above it  
> works once
> but not when repeated. I'm afraid I do not understand the  
> implementation of
> the devices well enough to know. Is there a good graphics tutorial  
> you could
> point me to?
>
> Thanks!
>
>
> -- 
> View this message in context:
http://www.nabble.com/jpeg-device-loop-problem-tp25123895p25123895.html
> Sent from the R help mailing list archive at Nabble.com.
>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT