How do you add a general label to facets in ggplot2 3.3.0?

Question

I want to add general labels to facets in ggplot2. My code looks like this:

library(ggplot2)
df <- data.frame(x= 1:100, y= 1:100,
                 sport= rep(c(TRUE, FALSE), each= 50),
                 female= rep(c(TRUE, FALSE)))

ggplot(df, aes(x, y)) +
  geom_point() +
  facet_grid(female ~ sport)

And the plot I get is:

As you can see the labels are not informative at all. How can I add general lebals in facets? Here, it is sport and female.

There is already a similiar question but the answer does not work with the current ggplot2 3.3.0 version.

Answer 1

You'll probably want to use the labeller argument. For your example, manual values will work, but probably assigning functions scales better for your real usecase.

Here is an example of both:

library(ggplot2)

df <- data.frame(x= 1:100, y= 1:100,
                 sport= rep(c(TRUE, FALSE), each= 50),
                 female= rep(c(TRUE, FALSE)))

p1 <- ggplot(df, aes(x, y)) +
  geom_point()

# Using manual values
p1 +
  facet_grid(
    female ~ sport,
    labeller = labeller(
      female = c("TRUE" = "A", "FALSE" = "B"),
      sport = c("TRUE" = "C", "FALSE" = "D")
    )
  )

# Using functions
your_labeller <- labeller(
  female = stringr::str_to_lower,
  sport = stringr::str_to_title
)

p1 +
  facet_grid(
    female ~ sport,
    labeller = your_labeller
  )

^{Created on 2020-03-24 by the reprex package (v0.2.1)}