I tried to construct a matrix of lists e.g. R> Matlist<-matrix(list(a1=c(1:4),b1=c(1:3),a2=c(1:9),b2=c(1:2)),nrow=2,ncol=2,byrow=F) Error: Unimplemented feature in copyVector V&R p52 talk about ragged arrays using a labelling factor. I am not sure what this means. Is it that the list indexing can be defined by two factors (of length 4 in this example) that hold the row and column indices? How would I reference a subset of list items then (Matlist[[Col==2]] ?) Trying something like this gives me R> Matlist[[Col==2]] Error: attempt to select more than one element My aim is to have a set of lists that I can refer to using matrix type indexing like Matlist[,2] or Matlist[,-1]. I appreciate any help Ross Darnell -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._