如何将平均线添加到R中的分组密度图中？

Question

我正在尝试绘制分组密度图并添加每个图的平均线；这是代码

data <- data.frame(
 Accuracy=abs(rnorm(140)),
Species=c(rep("A.All",20),rep("B. double",60),rep("C.single",60),
          rep("D.All",20),rep("E.double",60),rep("F.single",60)),

Modality=c(rep("All,w0",10),rep("double1,w0",10),rep("double2,w0",10),rep("double3,w0",10),
          rep("single1,w0",10),rep("single2,w0",10),rep("single3,w0",10),
          rep("All,w2",10),rep("double1,w2",10),rep("double2,w2",10),rep("double3,w2",10),
          rep("single1,w2",10),rep("single2,w2",10),rep("single3,w2",10))
)


p<-ggplot(data, aes(x=Accuracy, fill=Modality)) +
 geom_density(alpha=0.4)+
 facet_wrap(. ~ Species) +
 xlab("Accuracy") + ylab("Density")

library(plyr)
mu <- ddply(data, "Modality", summarise, grp.mean=mean(Accuracy))
head(mu)


# Add mean lines
a<-p+geom_vline(data=mu, aes(xintercept=grp.mean, color=Modality),
                linetype="dashed")+ xlab("Accuracy") + ylab("Density")

但是，根据输出图

平均线是绝对不正确的，例如对于左上角的第一张图片，两个密度图应该有两条线，但是创建了几条线并为所有图重复。

Answer 1

您可以同时指定Species 和Modality

plyr

dummy <- ddply(data, c("Species","Modality"), summarise, grp.mean=mean(Accuracy))

ggplot(data, aes(x=Accuracy, fill=Modality)) +
  geom_density(alpha=0.4)+
  facet_wrap(. ~ Species) +
  xlab("Accuracy") + ylab("Density") +
  geom_vline(data = dummy, aes(xintercept = grp.mean, color = Modality))

dplyr

library(dplyr)



dummy <- data %>%
  group_by(Species, Modality) %>%
  summarize(mean = mean(Accuracy))

ggplot(data, aes(x=Accuracy, fill=Modality)) +
  geom_density(alpha=0.4)+
  facet_wrap(. ~ Species) +
  xlab("Accuracy") + ylab("Density") +
  geom_vline(data = dummy, aes(xintercept = mean, color = Modality))