R - adding page numbers to PDF

Question

I\'m having trouble adding page numbers to PDFs. Here\'s how I\'m inserting pages / plots:

pdf( file = pdfFilePath , width = 11 , height = 8.5  )
for ( ...          


        

Answer 1

As mentioned by @Gavin, I also encountered the error when mixing ggplot with mtext.

Here is what works really nicely for me when using ggplot:

require(ggplot2)
require(grid)
printWithFooter = function(gg_obj, bottom_left = NULL, bottom_right = NULL) 
{
  print(gg_obj)
  if (!is.null(bottom_right))
  {
    label = textGrob(bottom_right,
                     x = 0.98,  # right side
                     y = 0.0,   # bottom
                     just="right", 
                     hjust = NULL,
                     vjust = -.5,
                     gp=gpar(fontsize=7, col="#333333"))
    grid.draw(label)
  }
  if (!is.null(bottom_left))
  {
    label = textGrob(bottom_left,
                     x = 0.02,  # left side
                     y = 0.0,   # bottom
                     just="left", 
                     hjust = NULL,
                     vjust = -.5,
                     gp=gpar(fontsize=7, col="#333333"))  
    grid.draw(label)
  }
}

## example

d = data.frame(x = runif(1:20), y = runif(1:20), facet = rep(1:4, each=5))
p = ggplot(d) + geom_point(aes(x=x, y=y)) + facet_wrap(~facet)
printWithFooter(p, "left", "right")