使用geom_vline在多个面的密度图中插入平均值

install.packages("ggplot2")
library(ggplot2)

# 创建示例数据集
data <- data.frame(group = rep(c("A", "B", "C"), each = 100),
                   value = c(rnorm(100), rnorm(100, mean = 2), rnorm(100, mean = 4)))

# 创建多个面的密度图
p <- ggplot(data, aes(x = value, fill = group)) +
  geom_density(alpha = 0.5) +
  facet_wrap(~ group, ncol = 3)

# 计算每个组的平均值
mean_values <- aggregate(value ~ group, data, mean)

# 在每个面的密度图中插入平均值
p + geom_vline(data = mean_values, aes(xintercept = value), color = "red", linetype = "dashed")