Saving trellis output to files in scripts...

With much help from Chuck Cleland, I was able to get xyplot to
generate the plot I wanted.  I'm trying to write a script (that can be
read using source("file")) to create the plots I want and save them to
files.

If I type the following lines into the R (in interactive mode), the
correct plot gets saved into the file myfile.ps with a size of 4,096
bytes:

----------------------------
require(lattice)

trellis.device("postscript", file="myfile.ps", color=FALSE,
paper="letter", horizontal=TRUE, onefile=TRUE)

xyplot(y ~ x, type="b", data.frame(x=1:5, y=5:1))

dev.off()
----------------------------

However, if I put the same lines into a file, "temp.txt", and type
source("temp.txt") into R, then myfile.ps ends up with a size of 2,332
bytes and shows a blank page when loaded into ghostscript.

When run using source, it looks like the device is not getting closed
correctly since if I type source("temp.txt") and then dev.list() R
responds:  "postscript 2"

If I type dev.off(), the file size then increases to 4,277 bytes, but
then the ps file is malformed.

Anyone know how to make this work?

Jamie