为手动添加的行添加一个条目到图例 [英] Add an entry to the legend for a manually added line

问题描述

我有一个用ggplot（ggplot + geom_bar）创建的直方图，并且像这样添加了一行：

  + geom_hline（aes（yintercept = 0.05），linetype ='dashed'）
  

我想添加一个进入图例，这将表明虚线是期望的值。

虽然在Stack Overflow上有类似的问题，但我找不到答案需要...

任何想法如何做到这一点？

>在ggplot问题的情况下做出可重复的例子非常方便，下次你应该这样做。答案如下：

pre $ g $ p $ ggplot（diamonds，aes（clarity，fill = cut））+ geom_bar（position =dodge ）+
＃线型必须是aes; show_guide = TRUE很重要
geom_hline（aes（yintercept = 1500，linetype =Expected value），
show_guide = TRUE）+
＃2表示虚线
scale_linetype_manual（Title ，values = 2）+
＃修复了一些问题，尝试linetype = 1，另一个图例将被破坏
guides（fill = guide_legend（override.aes = list（linetype = 0）））

I have a histogram created with ggplot (ggplot + geom_bar) and I added a line to it like so:

+ geom_hline(aes(yintercept = 0.05),linetype='dashed')

I would like to add an entry to the legend which will indicate that the dashed line is the expected value.

Although there are similar questions on Stack Overflow, I couldn't find the answer to what I need...

Any idea how to do it?

解决方案

It is quite convenient to make reproducible examples in case of ggplot questions, you should do that next time. Here is the answer:

ggplot(diamonds, aes(clarity, fill = cut)) + geom_bar(position = "dodge") + 
# linetype has to be aes; show_guide = TRUE is important
  geom_hline(aes(yintercept = 1500, linetype = "Expected value"), 
             show_guide = TRUE) + 
# 2 means dashed
  scale_linetype_manual("Title", values = 2) +
# This fixes some problems, try linetype = 1 and another legend will be ruined
  guides(fill = guide_legend(override.aes = list(linetype = 0)))

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