R/getChunkSize.R

In hydrosolutions/riversCentralAsia: Accompanying R Package to Applied Modeling of Hydrological Systems in Central Asia Course

#' Calculate the number of time steps to read from DST file for each model
#' component.
#'
#' RSMinerve result files can be stored in .dst files where time series of each
#' model component are stored in rows. \code{getChunkSize} can be used to
#' determine the chunk size of each model output. Typically used to deterimine
#' input to \code{readResultDST}.
#'
#' @param start_date Lubridate datetime of the start of the simulation
#' @param end_date Lubridate datetime of the end of the simulation
#' @param recordingTimeStep The simulations recording time step (in seconds) as
#'   character or as numeric.
#' @return A numeric of the number of time steps, including one header line, to
#'   be read.
#' @note Currently only hourly, daily and monthly time steps are implemented.
#' @examples
#' start_date <- lubridate::as_datetime("20.01.2021 00:00:00",
#'                                      format = "%d.%m.%Y %H:%M:%S")
#' end_date <- lubridate::as_datetime("25.01.2021 00:00:00",
#'                                    format = "%d.%m.%Y %H:%M:%S")
#' recordingTimeStep <- 3600  # In seconds
#' chunk_size <- getChunkSize(start_date, end_date, recordingTimeStep)
#' @family RS Minerve IO
#' @seealso \code{[readResultDST]}
#' @export
getChunkSize <- function(start_date, end_date, recordingTimeStep) {

  recordingTimeStep = as.numeric(recordingTimeStep)

  if (recordingTimeStep <= 86400) {

    # Sub-daily to daily time steps
    chunk_size <- lubridate::interval(start_date, end_date) /
      lubridate::seconds(1) / recordingTimeStep + 2

  } else if (recordingTimeStep == 2628000 | recordingTimeStep == 2592000) {

    # Montly time steps (365*24*60*60/12 | 60*60*24*30)
    chunk_size <- base::length(base::seq(start_date, end_date, "month")) + 2

  } else {

    cat("Warning: recordingTimeStep =", recordingTimeStep, "is currently not implemented. \n")
    cat("Returning NULL\n")
    return(NULL)

  }
  return(chunk_size)

}