Dear all,
I am having trouble creating a "jagged array" in R. I have found no commentary
on how to do it in the help files, but maybe I am misunderstanding the purpose
of some of the array functions (e.g. tapply).
I am using a longitudinal dataset where each individual has a different number
of time points (observations). I need to create correlation structures for
each individual which are necessarily different lengths. Currently I am using
for loops in an attempt to do so. The closest I can get is with the following
code (n=3) where I create matrices of the same dimensions with NA's for
timepoints not used. Perhaps there is simply a way to drop these NA's?
I would appreciate any thoughts on how to create a jagged array to store
matrices of different dimensions or direction towards a help-file or package
that will help me out.
Thanks in advance!
n<-3 #sample size
tim<-c(10,12,5) #number of observations per individual
tim.pts<-12 #number of possible observations
struc<-array(NA,dim=c(tim.pts,tim.pts,n))
for(i in 1:n){
for(k in 1:tim[i]){
for(j in k:tim[i]){
struc[k,j,i]<- (exp(-(j-k)))
struc[j,k,i]=struc[k,j,i]
}
}
}
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