set.seed(1)
b1<- rnorm(100)
b2<- rep(0:1,each=50)
b3<-b1+b2-b1*b2+rnorm(100,sd=0.5)
b2<-factor(b2,labels = c("种类1","种类2"))
xyplot(b1~b3 | b2,panel = function(b1,b3){
panel.xyplot(b1,b3)
panel.abline(v=mean(b1),h=mean(b3),lty=2)
panel.lmline(b1,b3,col="bluw")
})
我想根据我自己的构思创建一个xyplot绘图,但运行后却出现了

求大神解答。。。