用ggplot facet_wrap绘制每组的中位数

Question

所讨论的数据集是钻石（在dplyr中）。我试图打破价格直方图通过削减使用Facet_Wrap。我也希望每个情节都有中线。我就是这么做的-

by_cut <- group_by(diamonds, cut)

med <- by_cut %>% 
  summarise(medn = median(price))

diam <- diamonds %>% 
  mutate(med_cut = ifelse(cut == med$cut[1], med$medn[1],
                      ifelse(cut == med$cut[2], med$medn[2],
                             ifelse(cut == med$cut[3], med$medn[3],
                                    ifelse(cut == med$cut[4], med$medn[4], med$medn[5])))))

diam %>% 
  ggplot(aes(price)) +
  geom_histogram(binwidth = 100) +
  facet_wrap(~ cut, scales = "free_y") +
  geom_vline(aes(xintercept= med_cut), colour='red') 

不过，我肯定这不是达到结果的理想方法，所以我想知道，达到结果的最佳方法是什么？

基于@yeedle评论

diam <- diamonds %>% 
  group_by(cut) %>% 
  mutate(medn = median(as.numeric(price)))

diam %>% 
  ggplot(aes(price)) +
  geom_histogram(binwidth = 100) +
  facet_wrap(~ cut, scales = "free_y") +
  geom_vline(aes(xintercept= medn, group= cut), colour='red') 

Answer 1

diamonds %>% 
  group_by(cut) %>%
  mutate(med_price = median(as.numeric(price))) %>%
  ggplot(aes(price)) +
     geom_histogram(binwidth = 100) +
     geom_vline(aes(xintercept= med_price), colour='red') +
     facet_wrap(~ cut, scales = "free_y")