stat_summary(). The mean is often shown with a diamond, so we’ll use shape 23 with a white fill. We’ll also make the diamond slightly larger by setting
size = 3 (Figure 6.21):
library(MASS) # Load MASS for the birthwt data set ggplot(birthwt, aes(x = factor(race), y = bwt)) + geom_boxplot() + stat_summary(fun.y = "mean", geom = "point", shape = 23, size = 3, fill = "white") #> Warning: The `fun.y` argument of `stat_summary()` is deprecated as of ggplot2 3.3.0. #> ℹ Please use the `fun` argument instead. #> This warning is displayed once every 8 hours. #> Call `lifecycle::last_lifecycle_warnings()` to see where this warning was #> generated.