将vline添加到现有绘图并使其显示在ggplot2图例中？ [英] Add vline to existing plot and have it appear in ggplot2 legend?

问题描述

我有一些数据用于绘制直方图。我也有两组具有一定意义的阈值。

我可以用适当的样式绘制直方图和曲线。但是，我无法让我的vlines显示在图例中。我相信像这样的东西应该可以工作，但是图例项目不会显示。

  df<  -  data.frame （val = rnorm（300,75,10））
 
 cuts1 <-c（43,70,90）
 cuts2 <-c（46,79,86）
 
 ggplot（data = df，aes（x = val））+ 
 geom_histogram（）+ 
 geom_vline（xintercept = cuts1，
 linetype = 1，
 color =red，
 labels =Thresholds A，
 show_guide = TRUE）+ 
 geom_vline（xintercept = cuts2，
 linetype = 2，
 color = green，
 labels =Thresholds B，
 show_guide = TRUE）
  

<另外，如果我为剪切构建一个data.frame并进行审美映射，我可以让我的vlines显示在图例中。不幸的是，图例给了我两个叠加在一起的不同线条类型的实例：

pre $ cuts1 < - data.frame（阈值=阈值A，vals = c（43,70,90））
cuts2 < - data.frame（阈值=阈值B，vals = cuts2 <-c（46,79,86 ））

ggplot（data = df，aes（x = val））+
geom_histogram（）+
geom_vline（data = cuts1，aes（xintercept = vals，shape =阈值），
linetype = 1，
color =red，
labels =Thresholds A，
show_guide = TRUE）+
geom_vline（data = cuts2 ，aes（xintercept = vals，shape = Thresholds），
linetype = 2，
color =green，
labels =Thresholds B，
show_guide = TRUE）


所以，最后，我正在寻找的是直接手动添加两个设置图线，然后让它们在图例中正确显示。

解决方案

诀窍是将阈值数据所有在 same 数据框中，然后映射美学，而不是设置它们：

  cuts< ; --bbind（cuts1，cuts2）
 
 ggplot（data = df，aes（x = val））+ 
 geom_histogram（）+ 
 geom_vline（data = cuts，
 aes（xintercept = vals，
 linetype = Thresholds，
 color = Thresholds），
 show_guide = TRUE）
  

I have some data that I am using to plot a histogram. I also have two sets of thresholds that have some significance.

I am able to plot the histogram and the vlines with the appropriate styles. However, I cannot get my vlines to show up in the legend. I believe that something like this should work, however the legend items don't ever display.

df <- data.frame(val=rnorm(300, 75, 10))

cuts1 <- c(43, 70, 90)
cuts2 <- c(46, 79, 86)

ggplot(data=df, aes(x=val)) +
  geom_histogram() +
  geom_vline(xintercept=cuts1,
             linetype=1,
             color="red",
             labels="Thresholds A",
             show_guide=TRUE) +
  geom_vline(xintercept=cuts2,
             linetype=2,
             color="green",
             labels="Thresholds B",
             show_guide=TRUE)

Alternatively, if I construct a data.frame for my cuts and do an aesthetic mapping, I can get my vlines to show up in the legend. Unfortunately, the legend gives me two instances of the different line types superimposed on each other:

cuts1 <- data.frame(Thresholds="Thresholds A", vals=c(43, 70, 90))
cuts2 <- data.frame(Thresholds="Thresholds B", vals=cuts2 <- c(46, 79, 86))

ggplot(data=df, aes(x=val)) +
  geom_histogram() +
  geom_vline(data=cuts1, aes(xintercept=vals, shape=Thresholds),
             linetype=1,
             color="red",
             labels="Thresholds A",
             show_guide=TRUE) +
  geom_vline(data=cuts2, aes(xintercept=vals, shape=Thresholds),
             linetype=2,
             color="green",
             labels="Thresholds B",
             show_guide=TRUE)

So, in the end, what I'm looking for, is the most straightforward way to manually add two sets of lines to a plot, and then have them appear correctly in the legend.

解决方案

The trick is to put the threshold data all in the same data frame, and then map aesthetics, rather than set them:

cuts <- rbind(cuts1,cuts2)

ggplot(data=df, aes(x=val)) +
  geom_histogram() +
  geom_vline(data=cuts, 
             aes(xintercept=vals, 
                 linetype=Thresholds,
                 colour = Thresholds),
             show_guide = TRUE)

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