刻度线标记 ggplot 中日期的任一侧

问题描述

Ggplot 使用以下代码集中添加刻度线：

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()

但我需要在一年的任何一边做刻度线。我在刻度线图中进行了 Photoshop 处理，以显示我需要它们的位置。我可以使用什么代码在一年的任一侧添加刻度线？

解决方法

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

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,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 年 4 月 10 日创建}