Add text outside plot area

Question

Sample code

library(ggplot2)
ggplot(mtcars, aes(mpg, cyl, color = vs)) + geom_line()

How if it is possible to add arbitrary text to the x axis like in this example made using the plot above and then I wrote on it "arbitrary words"

Answer 1

I'm not entirely sure what you're trying to do so this may or may not generalise well.

That said, one possibility is to use annotate with coord_cartesian(clip = "off") to allow text outside the plot area.

ggplot(mtcars, aes(mpg, cyl, color = vs)) +
    geom_line() +
    annotate("text", x = 12.5, y = 3.5, label = "Arbitrary text") +
    coord_cartesian(ylim = c(4, 8), clip = "off")

Answer 2

You can use tag in ggplot2 (see ?ggplot2::labs) and specify it's position in theme

library(ggplot2)
ggplot(mtcars, aes(mpg, cyl, color = vs)) + 
    geom_line() +
    labs(tag = "arbitrary words") +
    theme(plot.tag.position = c(0.15, 0.02))