The following code is slow and ugly: count<-0 for(i in 1:nrow(ver)) for(j in 1:ncol(ver)) { count<-count+1 x[count]<-pt$x[ver[i,j]] y[count]<-pt$y[ver[i,j]] z[count]<-pt$z[ver[i,j]] } Please help me make it better. Thanks! Bill