添加带有自己的比例和图例的 geom答案

【问题标题】：Add geom with its own scales and legend添加带有自己的比例和图例的 geom
【发布时间】：2012-10-19 18:11:06
【问题描述】：

这可以说是对这些问题的跟进：

Add vline to existing plot and have it appear in ggplot2 legend?

我希望将几何图形添加到具有自己独立数据、比例和图例元素的绘图中。

我意识到这可能违反了图形原则的某些语法，但我经常发现自己想要图例中出现的垂直或水平线、单点、箭头等元素。

当其他几何映射中已经使用比例尺时，似乎会增加难度。

这里不是使用 iris 的漂亮示例：

p<-qplot(data=iris, x=Petal.Width,
         y=Sepal.Width,
         colour=Species,
         shape=as.factor(round(Petal.Length)),
         linetype=as.factor(round(Sepal.Length)),
         geom=c("line", "point"))

p<-p+geom_vline(xintercept=0.75, aes(linetype="Setosa vs Versicolor"))
p<-p+geom_vline(xintercept=1.75, aes(linetype="Versicolor vs Virginica"))

print(p)

目前产生的，缺少 vline 的线型和关联图例。

【问题讨论】：

标签： r ggplot2 legend

【解决方案1】：

更改您的geom_vline 调用，以在aes 调用中同时包含xintercept 和linetype。现在，linetype 没有任何效果（不仅仅是没有出现在图例中）。

qplot(data=iris, x=Petal.Width,
      y=Sepal.Width,
      colour=Species,
      shape=as.factor(round(Petal.Length)),
      linetype=as.factor(round(Sepal.Length)),
      geom=c("line", "point")) +
geom_vline(aes(xintercept=0.75, linetype="Setosa vs Versicolor")) +
geom_vline(aes(xintercept=1.75, linetype="Versicolor vs Virginica"))

## Warning messages:
## 1: The shape palette can deal with a maximum of 6 discrete values because
## more than 6 becomes difficult to discriminate; you have 7. Consider
## specifying shapes manually. if you must have them. 
## 2: The shape palette can deal with a maximum of 6 discrete values because
## more than 6 becomes difficult to discriminate; you have 7. Consider
## specifying shapes manually. if you must have them. 
## 3: Removed 4 rows containing missing values (geom_point). 
## 4: The shape palette can deal with a maximum of 6 discrete values because
## more than 6 becomes difficult to discriminate; you have 7. Consider
## specifying shapes manually. if you must have them.

【讨论】：