在時間序列圖中標記一段時間

Question

首先，讓我們創建一些假數據：

d <- c("2019-01-01", "2019-01-02", "2019-01-03", "2019-01-04", "2019-01-03", "2019-04-06", "2019-04-03", "2019-05-07", "2019-05-03", "2019-05-03", "2019-05-03", "2019-05-03", "2019-06-03", "2019-06-03", "2019-06-03", "2019-06-03", "2019-06-03", "2019-06-03", "2019-06-03", "2019-07-03", "2019-07-03", "2019-07-04", "2019-08-03", "2019-09-05", "2019-09-03", "2019-09-03", "2019-09-06", "2019-09-08", "2019-10-03", "2019-11-03", "2019-11-03", "2019-11-03", "2019-11-03", "2019-11-03", "2019-11-03", "2019-12-03", "2019-12-03")

df <- data.frame(dates=as.Date(d))

現在，我創建一個時間序列圖：

# aggregate data
df_plot <- df %>% mutate(month = lubridate::floor_date(dates, "month")) %>% 
  group_by(month) %>% summarise(count = n())

# plot data
ggplot(aes(x = month, y = count), data = df_plot) + geom_line() +
  scale_x_date() +
  geom_vline(xintercept = as.numeric(as.Date("2019-01-30")), linetype=4)

使用geom_vline(xintercept = as.numeric(as.Date("2019-01-30")), linetype=4)我可以用垂直線標記某個日期。 是否還有可能用彩色框或其他東西標記時間范圍（比如從 2019-01-30 到 2019-02-15）？

Answer 1

將geom_rect與ymin = -Inf和ymax = Inf結合使用。

xmin <- as.Date("2019-01-30")
xmax <- as.Date("2019-02-15")

ggplot(df_plot, aes(month, count)) + 
  geom_line() +
  scale_x_date() +
  geom_rect(aes(xmin = xmin, xmax = xmax, ymin = -Inf, ymax = Inf, 
    alpha = I(.1), fill  = I("lightblue"))) +
  annotate("text", label = "Some text", x = xmin, y = Inf, angle = 90,
    hjust = 1.1, vjust = -1)

（截圖后續）

另一種可能性是創建一個數據框regimes來保存邊界和標簽。 這與之前的代碼類似，但如果我們必須添加更多的 regimes ，那么只需向regimes添加行即可。

regimes <- data.frame(xmin = as.Date("2019-01-30"),
                      xmax = as.Date("2019-02-15"),
                      label = "Some text")

ggplot(regimes) + 
  geom_line(aes(month, count), df_plot) +
  scale_x_date() +
  geom_rect(aes(xmin = xmin, xmax = xmax, ymin = -Inf, ymax = Inf), 
    alpha = I(.5), fill = I("lightblue")) +
  geom_text(aes(x = xmin, y = Inf, label = label), angle = 90, 
    hjust = 1.1, vjust = -1)