x<-gl(4,1,12,labels=c('Lev1','Lev2','Lev3','Lev4'))
be<-c(2,3,-1,5)
Cmat<-diag(1,4);Cmat[2:4,1]<--1
Cmat
mean.vec<-be[as.numeric(x)]
set.seed(4387)
y<-rnorm(length(x),mean.vec,1)

data.frame(x,y)
summary(lm(y~x))


###################################################

(x1<-gl(5,1,10))
(x2<-gl(2,5,10))
be1<-c(-2,2,3,0,1)
be2<-c(0,2)
mean.vec<-be1[as.numeric(x1)]+be2[as.numeric(x2)]
set.seed(4387)
y<-rnorm(length(x1),mean.vec,1)
data.frame(x1,x2,y)

summary(lm(y~x1+x2))