您可以为ggplot中每个因子级别的图例添加计数吗？

Question

I am producing a scatterplot using ggplot, and will be colouring the data points by a given factor. The legend that is produced, details the colour assigned to each level of the factor, but is it possible for it to also count the number of points in each factor.

For example, I have included the code for the cars data set:

p <- ggplot(mtcars, aes(wt, mpg))
p + geom_point(aes(colour = factor(cyl)))

In this plot, I would be looking to have the count for each number of cylinders. So 4(Count 1), 6(Count 2) and 8(Count 3).

Thanks in advance.

Answer 1

you can try something like this

mtcars %>%
  group_by(cyl) %>%
  mutate(label = paste0(cyl, ' (Count ', n(), ')'))  %>%
  ggplot(aes(wt, mpg)) + 
    geom_point(aes(colour = factor(label)))