Annotate outside plot area once in ggplot with facets

Question

I want to add an annotation outside the plotting area in a faceted ggplot. I can get the annotation that I want, but it\'s repeated for each facet. How can I get this annota

Answer 1

With geom_text:

dummy <- data.frame(cyl = c(4), l = c("XX"), stringsAsFactors = F)

ggplot(mtcars, aes(x = hp, y = mpg)) +
  geom_point() +
  geom_text(data=dummy, aes(label=l), x = -20, y = 36) +
  facet_grid(.~cyl ) + 
  coord_cartesian(xlim = c(50, 350), ylim = c(10, 35), clip = "off")