Unexpected mfrow, layout behavior (pdf still has multiple pages)

Paul Johnston wrote:

My goal is to create a graph with one column and three rows into a
single graphic. The mfrow, mfcol, and layout functions all have the
same effect: three graphs are produced in a single pdf file, having
one graph per page.  This is not what I want (I didn't want multiple
pages).  Just before I sent this post, I was able to generate the
desired output with split.screen.  Is this the expected behavior of
mfrow and layout?

If you call them before opening the device, then yes, they will not
affect that device, but presumably some other device...

       -p

Paul

--------------------------------

My code is as follows (ToruosityPlot and DiameterPlot are essentially
identical to LDRPlot).

layout(matrix(1:3, ncol=1))
#par(mfrow=c(3,1))

pdf("results.pdf", width=4, height=3, pointsize=4, colormodel="cmyk",
onefile=TRUE)

TortuosityPlot(left, right)
DiameterPlot(left, right)
LDRPlot(left, right)

dev.off()

LDRPlot <- function(left, right)
  {
    plot(left$x, left$LDR, bty="n", ann=FALSE, xlim=c(-1500, 1000),
ylim=c(1.0, 1.5))
    abline(v=0, col=gray(.90))
    lines(left$x, left$LDR, col="green4", lty="solid")
    points(left$x, left$LDR, bg="limegreen", pch=21)
    lines(right$x, right$LDR, col="blue4", lty="dashed")
    points(right$x, right$LDR, bg="blue", pch=21)
    #title(main="LDR", xlab="Distance (um)", ylab="LDR",
col.main="black", col.lab=gray(.4), cex.main=1.2, cex.lab=1.0,
font.main=4, font.lab=3)
  }


platform       i386-apple-darwin8.11.1
arch           i386
os             darwin8.11.1
system         i386, darwin8.11.1
status
major          2
minor          8.1
year           2008
month          12
day            22
svn rev        47281
language       R
version.string R version 2.8.1 (2008-12-22)

--
  O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
 c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907