R/create_CRU_stack.R

In adamhsparks/getCRUCL2.0: 'CRU' 'CL' v. 2.0 Climatology Client

#' @title Create a list of terra rast objects from local disk files
#'
#'@description Automates importing \acronym{CRU} \acronym{CL} v.2.0 climatology
#' data and creates a \code{\link{terra}} \code{\link[terra]{rast}} of the
#' data.  If requested, minimum and maximum temperature may also be
#' automatically calculated as described in the data readme.txt file.  This
#' function can be useful if you have network connection issues that mean
#' automated downloading of the files using \R does not work properly.
#'
#' Nomenclature and units from readme.txt:
#' \describe{
#' \item{pre}{precipitation (millimetres/month)}
#'   \describe{
#'     \item{cv}{cv of precipitation (percent)}
#'   }
#' \item{rd0}{wet-days (number days with >0.1mm rain per month)}
#' \item{tmp}{mean temperature (degrees Celsius)}
#' \item{dtr}{mean diurnal temperature range (degrees Celsius)}
#' \item{reh}{relative humidity (percent)}
#' \item{sunp}{sunshine (percent of maximum possible (percent of day length))}
#' \item{frs}{ground-frost (number of days with ground-frost per month)}
#' \item{wnd}{10 metre windspeed (metres/second)}
#' \item{elv}{elevation (automatically converted to metres)}
#'}
#'For more information see the description of the data provided by
#' \acronym{CRU}, \url{https://crudata.uea.ac.uk/cru/data/hrg/tmc/readme.txt}
#'
#' @param pre Logical. Fetch precipitation (millimetres/month) from server and
#'  return in the data frame? Defaults to \code{FALSE}.
#' @param pre_cv Logical. Fetch cv of precipitation (percent) from server and
#' return in the data frame? Defaults to \code{FALSE}. NOTE. Setting this to
#' \code{TRUE} will always results in \strong{pre} being set to \code{TRUE} and
#' returned as well.
#' @param rd0 Logical. Fetch wet-days (number days with >0.1millimetres rain per
#' month) and return in the data frame? Defaults to \code{FALSE}.
#' @param dtr Logical. Fetch mean diurnal temperature range (degrees Celsius)
#' and return it in the data frame? Defaults to \code{FALSE}.
#' @param tmp Logical. Fetch temperature (degrees Celsius) and return it in the
#' data frame? Defaults to \code{FALSE}.
#' @param tmn Logical. Calculate minimum temperature values (degrees Celsius)
#' and return it in the data frame? Defaults to \code{FALSE}.
#' @param tmx Logical. Calculate maximum temperature (degrees Celsius) and
#' return it in the data frame? Defaults to \code{FALSE}.
#' @param reh Logical. Fetch relative humidity and return it in the data frame?
#' Defaults to \code{FALSE}.
#' @param sunp Logical. Fetch sunshine, percent of maximum possible (percent of
#' day length) and return it in data frame? Defaults to \code{FALSE}.
#' @param frs Logical. Fetch ground-frost records (number of days with ground-
#' frost per month) and return it in data frame? Defaults to \code{FALSE}.
#' @param wnd Logical. Fetch 10m wind speed (metres/second) and return it in the
#' data frame? Defaults to \code{FALSE}.
#' @param elv Logical. Fetch elevation (converted to metres) and return it in
#' the data frame? Defaults to \code{FALSE}.
#' @param dsn Local file path where \acronym{CRU} \acronym{CL} v.2.0 .dat.gz
#' files are located.
#' @examplesIf interactive()
#' # Create a terra rast object of temperature from tmp files in the tempdir()
#' # directory.
#'
#' download.file(
#'   url = "https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_tmp.dat.gz",
#'   destfile = file.path(tempdir(), "grid_10min_tmp.dat.gz")
#' )
#'
#' CRU_tmp <- create_CRU_stack(tmp = TRUE, dsn = tempdir())
#'
#' CRU_tmp
#'
#' @seealso
#' \code{\link{get_CRU_stack}}
#'
#' @return A \code{\link[base]{list}} of \code{\link{terra}}
#' \code{\link[terra]{rast}} objects of \acronym{CRU} \acronym{CL} v. 2.0
#' climatology elements
#'
#' @author Adam H. Sparks, \email{adamhsparks@@gmail.com}
#'
#' @note
#' This package automatically converts elevation values from kilometres to
#' metres.
#'
#' This package crops all spatial outputs to an extent of ymin = -60, ymax = 85,
#' xmin = -180, xmax = 180. Note that the original wind data include land area
#' for parts of Antarctica, these data are excluded in the terra rast objects
#' generated by this function.
#'
#' @export create_CRU_stack

create_CRU_stack <- function(pre = FALSE,
                             pre_cv = FALSE,
                             rd0 = FALSE,
                             tmp = FALSE,
                             dtr = FALSE,
                             reh = FALSE,
                             tmn = FALSE,
                             tmx = FALSE,
                             sunp = FALSE,
                             frs = FALSE,
                             wnd = FALSE,
                             elv = FALSE,
                             dsn = "") {
  if (!isTRUE(pre) & !isTRUE(pre_cv) & !isTRUE(rd0) & !isTRUE(tmp) &
      !isTRUE(dtr) & !isTRUE(reh) & !isTRUE(tmn) & !isTRUE(tmx) &
      !isTRUE(sunp) & !isTRUE(frs) & !isTRUE(wnd) & !isTRUE(elv)) {
    stop("\nYou must select at least one element for importing.\n",
         call. = FALSE)
  }

  .validate_dsn(dsn)

  files <- .get_local(pre,
                      pre_cv,
                      rd0,
                      tmp,
                      dtr,
                      reh,
                      tmn,
                      tmx,
                      sunp,
                      frs,
                      wnd,
                      elv,
                      cache_dir = dsn)

  if (length(files) == 0) {
    stop(
      "\nNo CRU CL 2.0 data files were found in ",
      dsn,
      ". ",
      "Please check that you have the proper file location.\n",
      call. = FALSE
    )
  }

  return(.create_stacks(tmn, tmx, tmp, dtr, pre, pre_cv, files))
}