r - 在离散的 x 轴上绘制 geom_vline

Question

我无法在绘图的 x 轴上绘制离散(因子)级别的垂直线。在此解决方案中似乎有效 drawing vertical line with factor levels in ggplot2

但是 OTH 这不适用于 geom_tile？

基本上，要删除 geom_tile 中的空白区域，我需要将 x 值转换为 numeric 到 factor levels 。但同时我想绘制一个带有数值的geom_vline。

这是问题所在

 df <- data.frame(
  x = rep(c(2, 5, 7, 9, 12), 2),
  y = rep(c(1, 2), each = 5),
  z = factor(rep(1:5, each = 2)))


 library(ggplot2)
 ggplot(df, aes(x, y)) +
  geom_tile(aes(fill = z), colour = "grey50")+
   geom_vline(aes(xintercept=6),linetype="dashed",colour="red",size=1)

要删除 geom_tile 中的空白，需要将 x 转换为 factor(x)但是当我这样做时 geom_vline 消失了!

Answer 1

一种解决方案可能是修改您的数据 - 将其转化为伪因子。

# Get rank of each x element within group
df$xRank <- ave(df$x, df$y, FUN = rank)

    x y z xRank
1   2 1 1      1
2   5 1 1      2
3   7 1 2      3
4   9 1 2      4
5  12 1 3      5
6   2 2 3      1
7   5 2 4      2
8   7 2 4      3
9   9 2 5      4
10 12 2 5      5

绘制值排名而不是值并将 x 轴元素标记为原始值:

library(ggplot2)
ggplot(df, aes(xRank, y)) +
    geom_tile(aes(fill = z), colour = "grey50") +
    # On x axis put values as labels
    scale_x_continuous(breaks = df$xRank, labels = df$x) +
    # draw line at 2.5 (between second and third element)
    geom_vline(aes(xintercept = 2.5), 
               linetype = "dashed", colour = "red",size = 1)