R help - Apr 2008 - Fixing the physical size of Trellis graphs panels

Dear R-users,

Please consider the following script:

#####

library(lattice)
ID <- rep(1:8,each=2)
x <- rep (c(1,2),8)
y <- c(rep(c(0.5,2),4),rep(c(50,1000),4))
df<-data.frame(ID,x,y)
g <- rep(1:2,each=8)
df.split<-split(df,g)

df.split

pdf(file="C:/Test.pdf")

for (i in 1:2) {
mydf<-as.data.frame(df.split[i])
myplot<-xyplot(mydf[,3]~mydf[,2]|mydf[,1],
       data=mydf,
       layout=c(2,2))
print(myplot)
}
dev.off()

You will find that the physical size of the panels are different on page 
1 and 2 because the axis labels have different length. Is it possible to 
fix the dimension of the panels regardless of the length of the axis labels?

Thank you for your input.

Sebastien

On 4/10/08, S?bastien <pomchip at free.fr> wrote:
> Dear R-users,
>
>  Please consider the following script:
>
>  #####
>
>  library(lattice)
>  ID <- rep(1:8,each=2)
>  x <- rep (c(1,2),8)
>  y <- c(rep(c(0.5,2),4),rep(c(50,1000),4))
>  df<-data.frame(ID,x,y)
>  g <- rep(1:2,each=8)
>  df.split<-split(df,g)
>
>  df.split
>
>  pdf(file="C:/Test.pdf")
>
>  for (i in 1:2) {
>  mydf<-as.data.frame(df.split[i])
>  myplot<-xyplot(mydf[,3]~mydf[,2]|mydf[,1],
>        data=mydf,
>        layout=c(2,2))
>  print(myplot)
>  }
>  dev.off()
>
>  You will find that the physical size of the panels are different on page
>  1 and 2 because the axis labels have different length. Is it possible to
>  fix the dimension of the panels regardless of the length of the axis
labels?
Yes, look at the entry for panel.width and panel.height in
?print.trellis. You could use it as

print(myplot, panel.width = list(x = 3, unit = "inches"))

etc. See ?unit in the grid package for details.

-Deepayan