r - ggplot2 中汇总统计的图例

Question

这是情节的代码

library(ggplot2)
df <- data.frame(gp = factor(rep(letters[1:3], each = 10)), y = rnorm(30))
library(plyr)
ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y))
ggplot(df, aes(x = gp, y = y)) +
   geom_point() +
   geom_point(data = ds, aes(y = mean), colour = 'red', size = 3)

我想要这个图的图例，它将识别数据值和平均值这样的事情

Black point = Data
Red point   = Mean.

我怎样才能做到这一点？

Answer 1

使用手动秤，即在您的情况下 scale_colour_manual .然后使用 aes() 将颜色映射到比例尺中的值每个geom的功能:

ggplot(df, aes(x = gp, y = y)) +
  geom_point(aes(colour="data")) +
  geom_point(data = ds, aes(y = mean, colour = "mean"), size = 3) +
  scale_colour_manual("Legend", values=c("mean"="red", "data"="black"))