R/cpm.all.schedule.R

In antoanne/ifmFramework: Financial evaluation of Projects

#' Generates all possible schedules for a cpm network
#'
#' @name cpm.all.schedule
#'
#' @aliases cpm_all_schedule genAllCpmSched
#'
#' @param cpm CPM vector with Early Start Time, Early Finish Time,
#' Late Start Time and Late Finish Time.
#'
#' @description Generates all possible schedules for a cpm network
#'
#' @export
#'
#' @return Matrix with all mininum makespan (the time to complete all jobs) cpm start time schedules
#'
#' @keywords critical path, scheduling, project activities
#'
#' @family scheduling
#'
#' @examples
#' #Use critical.path.method function to calculate a set of project
#' #activities:
#'
#' ex.cpm.activities.duration <- c(1,4,5,7,2,3,1)
#' ex.cpm.activities.successors <- list(c(2,3), 4, c(4,5), 6, 7, 7, c(0))
#' ex.cpm <- cpm(ex.cpm.activities.duration,
#'               ex.cpm.activities.successors)
#'
#' # Now, we have the CPM vector with:
#' # - est (Early Start Time)  - ex.cpm["est"]
#' # - eft (Early Finish Time) - ex.cpm["eft"]
#' # - lst (Late Start Time)   - ex.cpm["lst"]
#' # - lft (Late Finish Time)  - ex.cpm["lft"]
#'
#' ex.cpm.activities.schedule <-
#'    cpm.all.schedule(ex.cpm)
#'
cpm.all.schedule <- cpm_all_schedule <- genAllCpmSched <-
  function(cpm){
  est <- cpm$est
  slack <- (cpm$lst - cpm$est)

  # Constants
  slack <- slack + 1
  m <- prod(slack)
  n <- length(slack)

  # Variables
  current.schedule <- vector(mode = "numeric", length = n)
  schedule.matrix <- matrix(ncol = n, nrow = m)

  #Algorithm
  schedule.matrix[1,] <- current.schedule + est
  k <- 2 #row index for current.schedule

  for (j in 1:m){
    carry <- 1
    for (i in n:1){
      v <- current.schedule[i] + carry
      if (v >= slack[i]){
        current.schedule[i] <- 0
        carry <- 1
      } else {
        current.schedule[i] <- v
        carry <- 0
        sched <- current.schedule + est
        schedule.matrix[k,] <- sched
        k <- k+1
        break
      }
    }
  }
  return(schedule.matrix)
}