R/update_w.R

In fboehm/xu2015: Gibbs sampling for posterior inference when using determinantal point process (DPP) prior

#' Update w in Gibbs sampling
#'
#' @param delta a scalar hyperparameter for dirichlet
#' @param s a vector with one entry per observed data point of cluster assignments
#' @return w a weight vector of length $K$
#' @examples
#' update_w(1:4, c(1,1,2,2,3,3))
#'
#' @export

update_w <- function(mu, s, delta = 1){
  # delta is a K-vector
  K <- length(mu)
  n <- numeric(length = K)
  # n is a length-K vector
  for (k in 1:K){
    n[k] <- sum(s == k)
  }
  out <- as.numeric(gtools::rdirichlet(n = 1, alpha = delta + n))
  return(out)
}