R/single_par_cal.R

In kelvinyangli/mbmml: Learn Markov blankets using Minimum Message Length

#' Auxiliary function to mml_with_parents() and mml_with_parents_fast()
#'
#' This is an auxiliary function to both mml_with_parents() and mml_with_parents_fast() when the target
#' node has only one parent.
#' @param indexListPerNodePerValue A list of stored indices for each value of each node. It is obtained
#' by the function count_occurance().
#' @param commonParentsIndices commonParentsIndices
#' @param arityChild arityChild
#' @param targetIndex Index of the target node.
#' @param alpha A vector of concentration parameters for a Dirichlet distribution. Range is from zeor to positive infinity,
#' length is equal to the arity of the target variable.
#' @export
single_par_cal = function(indexListPerNodePerValue, commonParentsIndices, arityChild, targetIndex, alpha) {
  cumSum = 0
  for (j in 1:arityChild) { # for each child value j
    # N(pa_i, x_j)
    N_pa_i_x_j = length(intersect(commonParentsIndices, indexListPerNodePerValue[[targetIndex]][[j]]))
    # cumulative sum of log(N(pa_i, x_j)!)
    cumSum = cumSum + log_gamma(N_pa_i_x_j + alpha[j])
  }
  return(cumSum)
}