r - 带有 `geom_vline` 和 `geom_hline` 的 ggplot。任务：需要单独的图例

Question

library(tidyverse)
library(lubridate)

y <- rnorm(100)

df <- tibble(y) %>% 
  mutate(os = factor(rep_len(1:5, 100)),
         date = seq(from = ymd('2013-01-01'), by = 1, length.out = 100))

ggplot(df, aes(x = date, y = y, colour = os)) +
  geom_line() +
  geom_vline(
    aes(xintercept = min(date), linetype = 'os 1'), 
    colour = 'red') +
  geom_vline(
    aes(xintercept = median(date), linetype = 'os 2'), 
    colour = 'blue') +
  geom_hline(
    aes(yintercept = 1, linetype = "dashed"),
    colour = "black"
  ) +
  scale_linetype_manual(
    name = 'lines',
    values = c('os 1' = 1, 'os 2' = 1),
    guide = guide_legend(override.aes = list(colour = c('red', 'blue')))) 

输出：

输出有什么问题：

1. geom_hline失踪了。
2. 图例结合了 vline 和 hline 形成一个十字架。

正确的输出：

1. 应该绘制 geom_hline。
2. vlines 和 hlines 需要单独的图例。即，vline 图例中的线条应该是垂直的，而 hline 图例中的线条应该是水平的。

Answer 1

这可以通过

1. 添加hline到scale_linetype_manual
2. 在这个答案中使用自定义键字形。

library(tidyverse)
library(lubridate)

set.seed(123)

y <- rnorm(100)

df <- tibble(y) %>% 
  mutate(os = factor(rep_len(1:5, 100)),
         date = seq(from = ymd('2013-01-01'), by = 1, length.out = 100))

draw_key_cust <- function(data, params, size) {
  if (data$colour %in% c("red", "blue"))
    draw_key_vpath(data, params, size)
  else
    draw_key_path(data, params, size)
}

ggplot(df, aes(x = date, y = y, colour = os)) +
  geom_line() +
  geom_vline(
    aes(xintercept = min(date), linetype = 'os 1'), 
    colour = 'red', key_glyph = "cust") +
  geom_vline(
    aes(xintercept = median(date), linetype = 'os 2'), 
    colour = 'blue', key_glyph = "cust") +
  geom_hline(
    aes(yintercept = 1, linetype = "dashed"), 
    colour = "black", key_glyph = "cust"
  ) +
  scale_linetype_manual(
    name = 'lines',
    values = c('os 1' = 1, 'os 2' = 1, dashed = 2),
    guide = guide_legend(override.aes = list(colour = c('red', 'blue', 'black'))))