将 geom_vline 扩展到绘图之外

Question

我试图扩展我的 ggplot 图中的 geom_vline 线，以超出绘图空间并进入轴区域。这样做的目的是让这些线分隔轴标签，以便它可以与旁边的另一个图对齐（见下文）。

一些简短的示例代码（我有更多的行，因此需要水平线来保持直线）：

library(ggplot2)
library(cowplot)
library(dplyr)

#play data set
cars.data <- mtcars %>%
      mutate(car_name = rownames(mtcars)) %>%
      slice(1:6)

#I would like vlines to be extend in this plot
p1 <- ggplot(cars.data, aes(x = car_name, y = hp)) +
    geom_point() +
    scale_x_discrete(position = "top") +
    coord_flip() +
    geom_vline(aes(xintercept = seq(1.5, 6.5, 1)), color = "gray60") +
    xlab("")


p2 <- ggplot(cars.data, aes(y = car_name, x = 1)) +
  geom_text(aes(label = disp)) +
  xlab("disp") +
  geom_hline(aes(yintercept = seq(1.5, 6.5, 1)), color = "gray60")+
  theme(axis.title.y = element_blank(),
        axis.title.x = element_text(vjust = 0.5, angle = 30),
        axis.text = element_blank(),
        axis.line = element_blank(),
        axis.ticks = element_blank(),
        panel.background = element_rect(fill = "gray90"))

plot_grid(p1, p2, rel_widths = c(1,0.2))

这导致下图：

我正在寻找的是延长线，p1以便它们在图之间继续，几乎就像一个绘图表混合。我试过了，clip = "off"但它似乎没有成功。

Answer 1

您必须自己绘制线条，以确保在设置 时它们可以延伸超过绘图边界clip = "off"。我geom_segment()在这里使用并手动设置坐标中的限制。

您还需要对齐两个图plot_grid()以确保一切正常。

library(ggplot2)
library(cowplot)
library(dplyr)

#play data set
cars.data <- mtcars %>%
  mutate(car_name = rownames(mtcars)) %>%
  slice(1:6)

p1 <- ggplot(cars.data, aes(x = car_name, y = hp)) +
  geom_point() +
  scale_x_discrete(
    name = NULL,
    position = "top"
  ) +
  scale_y_continuous(expand = c(0, 0)) +
  coord_flip(clip = "off", ylim = c(80, 180)) +
  geom_segment(
    data = data.frame(x = seq(1.5, 6.5, 1), ymin = 80, ymax = 240),
    aes(x = x, xend = x, y = ymin, yend = ymax),
    inherit.aes = FALSE,
    color = "gray60"
  ) +
  xlab(NULL) +
  theme_cowplot()


p2 <- ggplot(cars.data, aes(y = car_name, x = 1)) +
  geom_text(aes(label = disp)) +
  xlab("disp") +
  geom_hline(aes(yintercept = seq(1.5, 6.5, 1)), color = "gray60") +
  theme_cowplot() +
  theme(
    axis.title.y = element_blank(),
    axis.title.x = element_text(vjust = 0.5, angle = 30),
    axis.text = element_blank(),
    axis.line = element_blank(),
    axis.ticks = element_blank(),
    panel.background = element_rect(fill = "gray90"),
    plot.margin = margin(7, 7, 7, 0)
  )

plot_grid(p1, p2, rel_widths = c(1,0.2), align = "h", axis = "bt")

^{由reprex 包于 2019 年 12 月 2 日创建(v0.3.0)}