set.seed(1)
x1 <- runif(1000,0,1)
x2 <- runif(1000,0,1)
y <- x1 + x2 + rnorm(1000)
l1 <- loess(y~x1)
l2 <- loess(y~x2)
plot(l1)
p1=predict(l1, data.frame(x1=seq(0,1,by=.05)))
p2=predict(l2, data.frame(x2=seq(0,1,by=.05)))
layout(matrix(1:2))
plot(p1,type='l'); lines(p2)
plot(p1-p2, type='l')