ggplot2で複数の折れ線をまとめてplot

すぐ忘れるのでメモ．

library("ggplot2")

y1 <- rnorm(10,5,1)
y2 <- rnorm(10,2,1)
y3 <- rnorm(10,3,1)
years <- 2001:2010

data <-data.frame(years,y1,y2,y3)
ggplot(data, aes(years)) +
  geom_line(aes(y = y1, colour = "y1")) +
  geom_line(aes(y = y2, colour = "y2"))+
  geom_line(aes(y = y3, colour = "y3"))