ggplot2中同一图例中的不同图例键 [英] Different legend-keys inside same legend in ggplot2

问题描述

假设我不需要适当的"变量映射，但仍希望使用图例键来帮助理解图表.我的实际数据类似于下面的df

Let's say I don't need a 'proper' variable mapping but still would like to have legend keys to help the chart understanding. My actual data are similar to the following df

df <- data.frame(id = 1:10, line = rnorm(10), points = rnorm(10))

library(ggplot2)

ggplot(df) +
  geom_line(aes(id, line, colour = "line")) +
  geom_point(aes(id, points, colour = "points"))

基本上，我希望与 points 相关的图例键是......只是一个点，中间没有线.我已经接近了这个:

Basically, I would like the legend key relative to points to be.. just a point, without the line in the middle. I got close to that with this:

library(reshape2)

df <- melt(df, id.vars="id")

ggplot() +
  geom_point(aes(id, value, shape = variable), df[df$variable=="points",]) +
  geom_line(aes(id, value, colour = variable), df[df$variable=="line",])

但它定义了两个单独的图例.修复第二个代码(并且必须重塑我的数据)也可以，但我更喜欢一种方法(如果有的话)来手动更改任何图例键(并继续使用第一个方法).谢谢！

but it defines two separate legends. Fixing the second code (and having to reshape my data) would be fine too, but I'd prefer a way (if any) to manually change any legend key (and keep using the first approch). Thanks!

感谢@alexwhan，你让我想起了变量映射.但是，到目前为止，我最简单的方法仍然是以下(非常糟糕的黑客！):

thanks @alexwhan you refreshed my memory about variable mapping. However, the easiest way I've got so far is still the following (very bad hack!):

df <- data.frame(id = 1:10, line = rnorm(10), points = rnorm(10))

ggplot(df) +
  geom_line(aes(id, line, colour = "line")) +
  geom_point(aes(id, points, shape = "points")) +
  theme(legend.title=element_blank())

这只是隐藏了两个不同图例的标题.

which is just hiding the title of the two different legends.

欢迎其他想法！！！

推荐答案

您可以在 guides() 函数中使用 override.aes= 来更改图例的默认外观.在这种情况下，您的指南是 color= 然后您应该设置 shape=c(NA,16) 以删除线的形状，然后 linetype=c(1,0) 从点删除线.

You can use override.aes= inside guides() function to change default appearance of legend. In this case your guide is color= and then you should set shape=c(NA,16) to remove shape for line and then linetype=c(1,0) to remove line from point.

ggplot(df) +
  geom_line(aes(id, line, colour = "line")) +
  geom_point(aes(id, points, colour = "points"))+
  guides(color=guide_legend(override.aes=list(shape=c(NA,16),linetype=c(1,0))))

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