R/BPCM.DIF.transform.R

In changxiulee/BayesianRasch: Bayesian Rasch Modeling

#' BPCM.DIF.transform
#'
#' Split the MCMC into multiple matrix for each group
#'
#' @param mcmc MCMC sample from a BPCM DIF model
#' @param item item involved in the model
#' @param p number of item
#' @param N number of subject for each group
#' @param K number of category
#' @param G number of group

BPCM.DIF.transform = function(mcmc, item, p, N, K, G) {
  mcmc.new = list()

  for(i in 1:G){
    group = matrix(NA, nrow(mcmc), p * K + N[i])
    temp = c()
    for(j in 1:p) {
      for(k in 1:K){
        temp = c(temp, paste0("beta[", j,",", k,"]"))
      }
    }
    colnames(group) = c(temp, paste0("theta[", i,",", 1:N[i], "]"))
    for(j in 1:p) {
      for(k in 1:K){
        group[, paste0("beta[", j,",", k,"]")] = mcmc[, paste0("beta[", j,",", k,"]")] + mcmc[, paste0("d[",i,",", j, ",", k, "]")]
      }
    }
    group[, paste0("theta[", i ,",", 1:N[i], "]")] = mcmc[, paste0("theta[", i ,",", 1:N[i], "]")]
    mcmc.new[[i]] = group
  }
  mcmc.new
}