让我们创建一些数据:
dd = data.frame(School_ID = c("A", "B", "C", "A", "B"),
Year = c(1998, 1998, 1999, 2000, 2005),
Value = c(5, 10, 15, 7, 15))
然后,为了在基础图形中创建绘图,我们创建一组的初始绘图:
plot(dd$Year[dd$School_ID=="A"], dd$Value[dd$School_ID=="A"], type="b",
xlim=range(dd$Year), ylim=range(dd$Value))
然后迭代地添加以下行:
lines(dd$Year[dd$School_ID=="B"], dd$Value[dd$School_ID=="B"], col=2, type="b")
lines(dd$Year[dd$School_ID=="C"], dd$Value[dd$School_ID=="C"], col=3, type="b")
我用过type="b"
显示点和线。
或者,使用ggplot2:
require(ggplot2)
##The values Year, Value, School_ID are
##inherited by the geoms
ggplot(dd, aes(Year, Value,colour=School_ID)) +
geom_line() +
geom_point()