R 在分布频率上计算平均值

我想绘制一个grupal频率分布图，并计算平均值。最直接的方法是：

library(dplyr)
library(ggplot2)
load(mtcars)
mtcars0=mtcars%>%group_by(cyl)%>%mutate(MeanMpg=round(mean(mpg),2))
mtcars1=mtcars%>%group_by(cyl)%>%summarize(MeanMpg=round(mean(mpg),2))
p <- ggplot(mtcars0, aes(mpg, fill=cyl)) +
  facet_wrap(. ~ cyl) + 
  geom_density(alpha=.2) +
  geom_vline(data=mtcars1, aes(xintercept=MeanMpg), linetype="dashed", size=1) +
  annotate("text", label = labels, size = 4, x = 15, y = 0.26)
p 

库（dplyr）
图书馆（GG2）
装载量（mtcars）
mtcars0=mtcars%>%组（cyl）%>%突变（平均mpg=round（平均mpg），2））
mtcars1=mtcars%>%按（气缸）分组%>%汇总（平均mpg=round（平均mpg，2））
p您可以使用
mtcars1
数据指定标签的位置：

ggplot(mtcars0, aes(mpg, fill=cyl)) +
  facet_wrap(. ~ cyl) + 
  geom_density(alpha=.2) +
  geom_vline(data = mtcars1, aes(xintercept = MeanMpg), linetype="dashed", size=1) +
  geom_text(data = mtcars1, aes(x = MeanMpg, y = 0.25, label = MeanMpg))


ggplot(mtcars0, aes(mpg, fill=cyl)) +
  facet_wrap(. ~ cyl) + 
  geom_density(alpha=.2) +
  geom_vline(data = mtcars1, aes(xintercept = MeanMpg), linetype="dashed", size=1) +
  geom_text(data = mtcars1, aes(x = MeanMpg, y = 0.25, label = MeanMpg))