打勾标记ggplot中日期的任一侧

Question

Ggplot 使用此代码集中添加刻度标记：

tibble(year = 2010:2020, count = sample(1:100, 11)) %>%
  mutate(year = paste0("01/01/", year)) %>%
  mutate(year = dmy(year)) %>%
  ggplot +
  geom_bar(aes(year, count), stat = "identity", width = 240, position = position_dodge(width = 0.1)) +
  scale_x_date(date_labels = "%y", date_breaks = "1 year") +
  scale_y_continuous(limits = c(0,100), expand = c(0, 0)) +
  theme_classic()

但我需要在一年中的任何一侧做记号。我已经在刻度线图中进行了 photoshop 以显示我需要它们的位置。我可以使用什么代码在年份的任一侧添加刻度线？

Answer 1

您可以使用geom_segment()自己绘制刻度线，关闭剪切并隐藏默认的。

library(ggplot2)
library(dplyr)
library(lubridate)

tbl <- tibble(year = 2010:2020, count = sample(1:100, 11)) %>%
  mutate(year = paste0("01/01/", year)) %>%
  mutate(year = dmy(year))

ggplot(tbl) +
  geom_bar(aes(year, count), stat = "identity", width = 240, position = position_dodge(width = 0.1)) +
  geom_segment(aes(x = year, xend = year), y = 0, yend = -1, 
               colour ="black", position = position_nudge(x = 240/2)) +
  geom_segment(aes(x = year, xend = year), y = 0, yend = -1, 
               colour ="black", position = position_nudge(x = -240/2)) +
  scale_x_date(date_labels = "%y", date_breaks = "1 year") +
  scale_y_continuous(limits = c(0,100), expand = c(0, 0),
                     oob = scales::oob_keep) +
  coord_cartesian(clip = "off") +
  theme_classic() +
  theme(axis.ticks = element_blank())

^{由reprex package (v1.0.0) 于 2021-04-10 创建}