Remove page numbers from marrangeGrob (or arrangeList) pdf

Remove page numbers from marrangeGrob (or arrangeList) pdf

marrangeGrob in the gridExtra arranges grobs (usually ggplots in my case)
in rows, columns and pages. It also numbers the pages.
require(ggplot2)
require(plyr)
require(gridExtra)
p <- function(plotdata) {
x <- ggplot(plotdata, aes(wt, mpg)) +
geom_point() +
ggtitle(plotdata$gear[1])
return(x)
}
all <- dlply(mtcars, .(gear), p)
allarranged <- do.call(marrangeGrob, c(all, nrow=1, ncol=2))
ggsave("multipage.pdf", allarranged, width=12)
That's a silly but reproducible example.
Now inspect the output of str(allarranged[[1]]) to reveal the objects of
the page numbers. Reduced to the essentials, they're here:
[[1]]
$ children :List of 5
..$GRID.frame.1925:List of 6
.. ..$ children :List of 5
.. .. ..$ GRID.cellGrob.1927:List of 10
.. .. .. ..$ children :List of 1
.. .. .. .. ..$ GRID.text.1845:List of 11
.. .. .. .. .. ..$ label : chr "page 1 of 2"
I made up the first few lines there because I'm having trouble writing the
output of str() to file. The point stands, though. $label is the
problem-child of many grandparents. There are also several $labels per
arrangelist (arrangeList is the output class of arrangeGrob).
Once you've figured out where the $labels are, then this works:
allarranged[[1]]$children$GRID.frame.1770$children$GRID.cellGrob.1772$children$GRID.text.1690$label
<- NULL
But how to predict that whole tree, or recurse through it looking for
$labels? If that weren't such an interesting problem I'd probably just
contact the gridExtra maintainer.