一种解决方案可能是修改数据-将其转换为
拟因素
.
# Get rank of each x element within group
df$xRank <- ave(df$x, df$y, FUN = rank)
x y z xRank
1 2 1 1 1
2 5 1 1 2
3 7 1 2 3
4 9 1 2 4
5 12 1 3 5
6 2 2 3 1
7 5 2 4 2
8 7 2 4 3
9 9 2 5 4
10 12 2 5 5
打印值列组而不是值,并将X轴元素标记为原始值:
library(ggplot2)
ggplot(df, aes(xRank, y)) +
geom_tile(aes(fill = z), colour = "grey50") +
# On x axis put values as labels
scale_x_continuous(breaks = df$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)