I need some help interpreting the following code which is part of a mutlilevel model simulation with 2 levels.? I've put in comments with my understanding of the code, but I'm not sure how [i2id] is functioning.? It's defined in another part of the program as?l2id<-rep(c(1:n2),each=n1) which looks like a number corresponding to the level 1 and 2 sample size (n1, n2).? Can someone explain what?[i2id] is telling x[,3] and x[,4]? ? macpred<-rmultinom(n2,1,c(0.15,0.30,0.55)) ##?generate one multinomial variable of length=1 with probabilities of .15, .30 and .55 and do this n2 times ? x[,3]<-macpred[1,][l2id] ?##assign the first mutinomial value to column 3 ? x[,4]<-macpred[2,][l2id] ##assign the second multinomial value to column 4