R/calc_queue_load.R

In NHSRwaitinglist: Waiting List Metrics Using Queuing Theory

#' @title Calculate Queue Load
#'
#' @description Calculates the queue load. The queue load is the number of
#'   arrivals that occur for every patient leaving the queue (given that the
#'   waiting list did not empty). It could also be described as the rate of
#'   service at the queue. The queue load is calculated by dividing the demand
#'   by the capacity: queue_load = demand / capacity.
#'
#' @param demand Numeric value of rate of demand in same units as target wait -
#'   e.g. if target wait is weeks, then demand in units of patients/week.
#' @param capacity Numeric value of the number of patients that can be served
#'   (removals) from the waiting list each week.
#'
#' @return Numeric value of load which is the ratio between demand and capacity.
#'
#' @export
#'
#' @examples
#' # If 30 patients are added to the waiting list each week (demand) and 27
#' # removed (capacity) this results in a queue load of 1.11 (30/27).
#' calc_queue_load(30, 27)
#'
calc_queue_load <- function(demand, capacity) {
  check_class(demand, capacity)
  load <- demand / capacity

  load
}