ggplot中的多个轴标题中的颜色 [英] multiple colors in axes titles in ggplot

问题描述

我如何在ggplot中为轴标签设置多种颜色？

How can I have multiple colors for an axes label in ggplot?

作为一个例子，而不是图例，我希望y轴标签是红色和绿色对应于以下图中的不同点：$ b​​
$ b

As an example, instead of a legend, I would like the y-axis label to be red and green to correspond to the different points in the following plot:

p <- ggplot(mpg[mpg$model=="a4",],aes(x=trans,y=cty))+geom_point(color="red")+
     geom_point(aes(y=hwy),color="dark green") +
     ylab("MPG (city); MPG (hwy)")

我知道我可以使用主题控制整个y轴标签的颜色，如下所示：

I know I can control the color of the entire y-axis label using theme as follows:

p <- p + theme(axis.title.y = element_text(color="red"))

但是， MPG（hwy）为深绿色。有没有办法在ggplot中做到这一点？

But, in the plot I want the "MPG (hwy)" to be in dark green. Is there a way to do this in ggplot?

推荐答案

我不认为您应该滥用轴标题作为图例，但您可以在网格级别执行此操作：

I don't think you should abuse an axis title as a legend, but you can do this at the grid level:

library(ggplot2)

p <- ggplot(mpg[mpg$model=="a4",],aes(x=trans,y=cty))+
  geom_point(color="red")+
  geom_point(aes(y=hwy),color="dark green") +
  ylab("MPG (city); MPG (hwy)")

g <- ggplotGrob(p)

g[[1]][[7]]$label <- c("MPG (city);",  "MPG (hwy)")
g[[1]][[7]]$gp$col <- c("red", "dark green")
library(grid)
g[[1]][[7]]$y <- unit(c(0.45, 0.54), "npc")
#fiddle with the coordinates until the positioning fits for your specific strings

plot(g)

当然通过使用适当的颜色变量映射简单地创建图例将是更可取的。

Of course it would be preferable to simply create a legend by using proper mapping of the color variable.

这篇关于ggplot中的多个轴标题中的颜色的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！