除了par(new=TRUE)设置外,有些函数本身就具有add选项
set.seed(1234)
plot(dist~speed,data=cars,pch=17,col="red",cex=1)
with(cars,symbols(dist~speed,circles=runif(length(speed),0,1),
pch=16,inches = .5,add=TRUE))
z <- lm(dist ~ speed, data = cars)
abline(z,col="blue")
curve(tan,from=0,to=8*pi,n=100,add=TRUE)
lines(stats::lowess(cars))
points(10,100,pch=16,cex=3,col="green")
text(10,80,"text here",cex=3)