R/ddply-jags-sample.R

In poissonconsulting/jaggernaut: Bayesian Analyses using 'JAGS'

#' @title ddply JAGS sample
#'
#' @description
#' Combines JAGS samples in a jags_sample object by by using function fun
#' 
#' @param object a jags_sample object.
#' @param by the variables to combine by (using ddply).
#' @param fun the function to using when combining samples (by default fun = sum). 
#' @return a jags_sample object
#' @seealso \code{\link{predict.jags_analysis}}
#' @export
ddply_jags_sample <- function(object, by, fun = sum) {
  if (!is.jags_sample(object))
    stop("object must be class jags_sample")

  fun_vs <- function(x, fun) {
    class(x) <- c("data.frame", "jags_sample")
    samples <- samples(x)
    return(apply(samples, MARGIN = 2, FUN = fun))
  }
  object %<>% plyr::ddply(.variables = by, .fun = fun_vs, fun = fun)
  class(object) <- c("data.frame","jags_sample")
  return(object)
}