r - 如何向每个面板添加一条平均线是facet_grid()对象？

Question

我这里有一个示例数据集:

data = data.frame(Region = c(rep("Upper",50), rep("Lower", 50)),
                  Weight = c(rnorm(50, 2, 1), rnorm(50, 4, 1)))

我想在 ggplot 中创建一个直方图，每个直方图的平均值都用红线覆盖。

ggplot(data=data, aes(x=Weight))+geom_histogram()+geom_vline(xintercept=mean(Weight), col="red")+facet_grid(Region~.)

Answer 1

按区域对数据进行分组，并计算每个权重的平均值。

data <- data %>% group_by(Region) %>%  mutate(mean = mean(Weight))

ggplot(data, aes(x = Weight)) +
  geom_histogram() +
  facet_grid(Region~.) +
  geom_vline(aes(xintercept = mean, group = Region), colour = 'red')