如何向每个面组的 ggplot 添加不同的 x 截距线 (R)

Question

我有一些类似于以下内容的数据：

library(dplyr)
library(ggplot2)

dates <- c('2023-01-01','2023-01-02','2023-01-03','2023-01-04','2023-01-05','2023-01-06',
          '2023-01-07','2023-01-08','2023-01-09','2023-01-10','2023-01-11','2023-01-12',
          '2023-01-01','2023-01-02','2023-01-03','2023-01-04','2023-01-05','2023-01-06',
          '2023-01-07','2023-01-08','2023-01-09','2023-01-10','2023-01-11','2023-01-12',
          '2023-01-01','2023-01-02','2023-01-03','2023-01-04','2023-01-05','2023-01-06',
          '2023-01-07','2023-01-08','2023-01-09','2023-01-10','2023-01-11','2023-01-12')

values <- c(1,2,10,15,16,17,17,16,15,12,10,8,2,5,6,7,7,7,7,8,8,8,9,8,20,19,18,10,10,7,6,6,5,5,3,2)

grp1 <-rep('Group1',12)
grp2 <-rep('Group2',12)
grp3 <-rep('Group3',12)

groups <- c(grp1, grp2, grp3)

df <- cbind(dates, values, groups) |>
  as.data.frame() |>
  mutate(values = as.numeric(values),
         dates = as.Date(dates))

我想绘制每组随时间变化的值。所以，我构建了以下 ggplot 代码：

ggplot(data = df, aes(x = dates, y = values, color = groups)) +
  geom_line() +geom_point() + 
  facet_wrap(~ groups, scales = 'free_y', ncol = 1)

但是，我想添加每个面组都不同的垂直 x 截距线。这是我尝试满足此要求的一些额外代码：

cutoff_dates <- c('2023-01-02', '2023-01-04', '2023-01-06')

ggplot(data = df, aes(x = dates, y = values, color = groups)) +
  geom_line() +geom_point() + 
  facet_wrap(~ groups, scales = 'free_y', ncol = 1) +
  geom_vline(xintercept = as.Date(cutoff_dates), linetype = 'dashed')

但是，这会将每个截止值添加到每个分组图中。我希望第一个截止日期适用于第一组，第二个截止日期适用于第二组，依此类推。我应该如何修改我的代码才能达到这个结果？

谢谢！

Answer 1

您可以在不同的数据框中添加截止值，并将其映射为

aes()

内的美学

geom_vline()

：

cutoff_dates <- data.frame(
  cutoff = c('2023-01-02', '2023-01-04', '2023-01-06'),
  groups = c("Group1", "Group2", "Group3"))

ggplot(data = df, aes(x = dates, y = values, color = groups)) +
  geom_line() +
  geom_point() + 
  facet_wrap(~ groups, scales = 'free_y', ncol = 1) +
  geom_vline(data = cutoff_dates,
             mapping = aes(xintercept = as.Date(cutoff)), linetype = 'dashed')