R/readPrjNumVals.R

In CentreForHydrology/CRHMr: Pre- and post- processing for CRHM

#' Reads numeric values from a CRHM project text object
#' @description Reads specified number of numeric values from a project file variable.
#' This is an internal function and is not able to be called by a function outside of
#' \pkg{CRHMr}, as it is not exported. This documentation is for maintenance purposes.
#'
#' @param prj Required. A CRHM file read into memory as a sequence of lines, as
#' returned from \code{readPrj}.
#' @param searchString Required. The identifying string.
#' @param value_count Required. The number of values to be read in.
#'
#' @return If successful, returns a vector with the specified number of values.
#' If unsuccessful, returns the value \code{FALSE}.
#' @keywords internal
#' @examples \dontrun{
#' hru_area <- readPrjNumVals(Bologna, 'hru_area', 19)}
#'
readPrjNumVals <- function(prj, searchString, value_count){
  # searches for the specified string, reads in the following lines and parses them
  prj_lines <- length(prj)
  line_num <- grep(searchString, prj, fixed = TRUE) + 1

  # search read until all values read in
  all_vals <- c()
  total_val_count <- 0
  done <- FALSE

  while (!done) {
    # check to see if numeric or not
    current <- prj[line_num]
    current_vals <- parseNums(current)
    current_val_count <- length(current_vals)
    all_vals <- c(all_vals, current_vals)
    total_val_count <- total_val_count + current_val_count

    if (total_val_count == value_count)
      done <- TRUE
    else
      line_num <- line_num + 1

    if ((total_val_count > value_count) | (line_num > prj_lines)) {
      cat("Error: couldn't find values\n")
      return(FALSE)
    }
  }

  return(all_vals)
}