R help - May 2005 - Lattice plot within a "for" loop does not happen?

I am trying to do a series of xyplots plots, using a "for" loop to  
substitute the appropriate variables for each plot. The basic command  
works fine by itself and produces a nice plot:

 > i<-3
 >  trellis.device(theme="col.whitebg")
 >  xyplot(as.formula(paste(tmp00[2*i], "~ ", tmp00[(2*i)-1],
+                             "|Blastomere+Phenotype",
sep="")),
+         data=tmp1,
+         panel=function(x,y,...){
+           panel.xyplot(jitter(x), jitter(y), pch=16, col="red")
+           if (max(x, na.rm=T)!=0.0) panel.xyplot(x, y, type="r",  
lwd=2)
+        })
 >

BUT, when I stick this in a loop, I get a bunch of blank graphics  
devices. This happens even if the loop only executes once. I could  
just go through and do these one by one, but I was curious if I was  
overlooking something obvious. Thank you for any advice.

=================================================================George W.
Gilchrist                        Email #1: gwgilc at wm.edu
Department of Biology, Box 8795          Email #2: kitesci at cox.net
College of William & Mary                    Phone: (757) 221-7751
Williamsburg, VA 23187-8795                    Fax: (757) 221-6483
http://gwgilc.people.wm.edu/

Hi

many times answered. Just enter

lattice loop R

into Google and you are there

Explicite printing lattice object is what you need.

Cheers
Petr


On 13 May 2005 at 10:09, George W. Gilchrist wrote:
> I am trying to do a series of xyplots plots, using a "for" loop
to
> substitute the appropriate variables for each plot. The basic command 
> works fine by itself and produces a nice plot:
> 
>  > i<-3
>  >  trellis.device(theme="col.whitebg")
>  >  xyplot(as.formula(paste(tmp00[2*i], "~ ", tmp00[(2*i)-1],
> +                             "|Blastomere+Phenotype",
sep="")),
> +         data=tmp1,
> +         panel=function(x,y,...){
> +           panel.xyplot(jitter(x), jitter(y), pch=16, col="red")
if
> +           (max(x, na.rm=T)!=0.0) panel.xyplot(x, y, type="r",  
> lwd=2)
> +        })
>  >
> 
> BUT, when I stick this in a loop, I get a bunch of blank graphics 
> devices. This happens even if the loop only executes once. I could 
> just go through and do these one by one, but I was curious if I was 
> overlooking something obvious. Thank you for any advice.
> 
> =================================================================>
George W. Gilchrist                        Email #1: gwgilc at wm.edu
> Department of Biology, Box 8795          Email #2: kitesci at cox.net
> College of William & Mary                    Phone: (757) 221-7751
> Williamsburg, VA 23187-8795                    Fax: (757) 221-6483
> http://gwgilc.people.wm.edu/
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
Petr Pikal
petr.pikal at precheza.cz

> BUT, when I stick this in a loop, I get a bunch of blank graphics  
> devices. This happens even if the loop only executes once. I could  just 
> go through and do these one by one, but I was curious if I was  
> overlooking something obvious. Thank you for any advice.
  You're overlooking something like line 800 of the documentation for 
xyplot:

  Value:

      An object of class ``trellis''. The `update' method can be
used to
      update components of the object and the `print' method (usually
      called by default) will plot it on an appropriate plotting device.


  xyplot doesn't actually make any marks on the screen. Oh no. It 
returns an object. You have to make that object make the marks on the 
screen. This happens automatically when you run something interactively, 
but not inside a function.

  So wrap your xyplot call in a print() function inside your loop:

  for(i in 1:10){
    print(xyplot(....whatever....))
  }

  Its probably in the R-FAQ as well, since my original feeling was that 
this behaviour was chosen in order to confuse people and see how many 
people read the FAQ... :)

Baz