Layering text outside the plot region in a levelplot

Hello list,

I've always wanted to figure out how to put legend captions in my
levelplots, and so when I came across this example today (from
http://r.789695.n4.nabble.com/scale-caption-on-levelplot-td3072400.html):

   library(grid)
   x <- sort(rnorm(100,50,10))
   y <- sort(runif(100,0,20))
   d <- expand.grid(x=x, y=y)
   d$z <- x + y
   graphics.off()
   p <- levelplot(z ~ x*y, d,
             par.settings=list(
               layout.widths=list(right.padding=4),
               layout.heights=list(top.padding=6)),
             colorkey = TRUE)
   print(p)

   ## now add the text
   grid.text('here and there', x=.98, y=.5, rot=-90,
     gp = gpar(col=4,
         fontfamily="HersheyGothicEnglish", cex=2))

This works and is fine, except in my code I use the layer() function and
save to a png, which changes the code as such:

   library(grid)
   library(latticeExtra)
   x <- sort(rnorm(100,50,10))
   y <- sort(runif(100,0,20))
   d <- expand.grid(x=x, y=y)
   d$z <- x + y
   graphics.off()
   p <- levelplot(z ~ x*y, d,
             par.settings=list(
               layout.widths=list(right.padding=4),
               layout.heights=list(top.padding=6)),
             colorkey = TRUE)
   #print(p)

   ## now add the text layer
   p <- p + layer(grid.text('here and there', x=.98, y=.5, rot=-90,
     gp = gpar(col=4,
         fontfamily="HersheyGothicEnglish", cex=2)))

   png("output.png")
   plot(p)
   dev.off()

Now, with these changes, the text moves inside the plot region, instead of
outside in the margins. It seems like once the grid.text is  converted by
the layer(), the x and y positions become relative to the plot region
instead of the whole graph, and any values of x and y larger than 1 will
move the text out of view.

So, is there a way I can use layer() to add text in the margins outside the
plot region? Or are there suggestions on other ways in which I could add
text to a plot margin?

Thanks,

Jooil


--
#############################################
Jooil Kim
Postdoc Fellow
Scripps Institution of Oceanography, UC San Diego
Mailing address:
9500 Gilman Drive # 0244
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jooilkim at ucsd.edu (kji2080 at gmail.com)
tel)+1-858-534-2599
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