R/cluster.R

In socale/frailtypack: Shared, Joint (Generalized) Frailty Models; Surrogate Endpoints

#' Identify clusters
#' 
#' This is a special function used in the context of the models for grouped
#' data. It identifies correlated groups of observations defined by using
#' 'cluster' function, and is used of 'frailtyPenal' formula for fitting
#' univariate and joint models.
#' 
#' 
#' @usage cluster(x)
#' @param x A character, factor, or numeric variable which is supposed to
#' indicate the variable group
#' @return \item{x}{A variable identified as a cluster }
#' @seealso \code{\link{frailtyPenal}}
#' @keywords misc
#' @export
#' @examples
#' 
#' 
#' \dontrun{
#' 
#' data(readmission)
#' modSha <- frailtyPenal(Surv(time,event)~as.factor(dukes)+cluster(id),
#' n.knots=10,kappa=10000,data=readmission,hazard="Splines")
#' 
#' print(modSha)
#' 
#' }
#' 
#' 
"cluster" <- function(x)
 {
	x
 }