r - 如何将观察数添加到箱线图

Question

我正在尝试弄清楚如何向我的箱形图添加观察次数。包中的示例演示了如何在箱线图上添加观察数。但我需要在 x 轴上写下观察数，我将基于此制作一个可重现的示例。

# function for number of observations 
give.n <- function(x){
 return(c(y = median(x)*1.05, label = length(x))) 
# experiment with the multiplier to find the perfect position
}


# plot
ggplot(mtcars, aes(factor(cyl), mpg, label=rownames(mtcars))) +
 geom_boxplot(fill = "grey80", colour = "#3366FF") +
 stat_summary(fun.data = give.n, geom = "text", fun.y = median) 

Answer 1

您可以创建一个摘要 data.frame 并将其作为数据参数传递给 geom_text 层。

library(dplyr)
df <- count(mtcars, cyl)

# plot
ggplot(mtcars, aes(factor(cyl), mpg, label=rownames(mtcars))) +
  geom_boxplot(fill = "grey80", colour = "#3366FF") +
  geom_text(data = df, aes(y = 0, label = n))