[R] Concat Multiple Plots into one PNG figure

[Gundala Viswanath]

Dear experts,

I tried to put the two plots into one final PNG figure
with the following script.

However instead of giving 2 plots  in one figure,
it only gives the the last plot in one figure.

What's wrong with my script below?

__BEGIN__
in_fname <- paste("mydata.txt.",sep="")
out_fname <- paste("finalplot.png",sep="")

dat <- read.table(in_fname, comment.char = "!" , na.strings = "null");
dat.pca <- prcomp(dat[,1:ncol(dat)], retx=TRUE, scores=TRUE)

trellis.device("png", color=TRUE)
png(out_fname)

# End figure expected to be 1 row 2 columns
par(mfrow = c(1,2))

# Two plots which I want to put into one PNG figure
xyplot(dat.pca$x[,1] ~ dat.pca$x[,2], xlab="First Component",
ylab="Second Component")
xyplot(dat.pca$x[,2] ~ dat.pca$x[,3], xlab="Second Component",
ylab="Third Component")

dev.off()

__END__

-- 
Gundala Viswanath