Dear Shuguang,
Here are two ways. Perhaps they are not efficient enough, but the work:
# Data
mydata=read.table(textConnection("
factorA factorB
0 0
0 0
1 0
0 1
1 1"),header=TRUE)
closeAllConnections()
# Option 1
mydata$factorC=as.factor(
apply(mydata,1,function(x){
paste(x,sep="",collapse="")
}
))
levels(mydata$factorC)<-list("0"="00", "1"="10", "2"="01","3"="11")
mydata
# Option 2
# You'll need to read the data again to see how this option works
mydata$factorC<-apply(mydata,1,function(x){
ifelse(sum(x)==0,0,
ifelse(x[1]==1 & x[2]==0,1,
ifelse(x[1]==0 & x[2]==1,2,3)))
}
)
mydata
HTH,
Jorge
On Tue, Nov 4, 2008 at 10:29 AM, Shuguang Sun <[EMAIL PROTECTED]> wrote:
> How to generate a new factor variable by two other factor variables?
>
> For example, if I have two factor variables, factorA and factorB,
> factorA factorB
> 0 0
> 0 0
> 1 0
> 0 1
> 1 1
>
> Is there a simple way to generate a new 4-levels factor variable as
>
> factorC factorA factorB
> 0 0 0
> 0 0 0
> 1 1 0
> 2 0 1
> 3 1 1
>
> --
> Shuguang Sun
> Fudan University, China
>
> ______________________________________________
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