Add image (png file) to header of pdf file created with R

Question

I am trying to add an .png image (logo) to the header of my pdf report of graphs created with ggplot and printed to pdf.

I found the following example how to add a i

Answer 1

here's a suggestion,

library(ggplot2)
p.example = qplot(mpg, wt, data = mtcars)

library(grid)
library(gtable)
ann <- rasterGrob(mypng, width=unit(1,"cm"), x = unit(0.5,"cm"))
g <- ggplotGrob(p.example)

g <- gtable_add_rows(g, grobHeight(ann), 0)
g <- gtable_add_grob(g, ann, t=1, l=4)
grid.newpage()
grid.draw(g)