Let us start with the following definitions
xxx<-rep(c(1,2),times=5)
yyy<-rep(c(1,2),each=5)
a<-c(11,12)
b<-matrix(1:4,2,2)
a[xxx] produces
[1] 11 12 11 12 11 12 11 12 11 12
b[xxx,yyy] produces
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]11111333
On Thu, 8 Sep 2005, Erich Neuwirth wrote:
>
> sapply(1:length(xxx),function(x)b[xxx[x],yyy[x]])
> does what I need and produces
> [1] 1 2 1 2 1 4 3 4 3 4
>
> Is there a function taking xxx,yyy, and b as arguments
> producing the same result?
b[cbind(xxx,yyy)]
> Essentially, I am asking for a vers
