R/get_prism_normals.R

In ropensci/prism: Access Data from the Oregon State Prism Climate Project

#' Download data for 30 year normals of climate variables
#' 
#' @description Download data from the prism project for 30 year normals at 4km 
#'   or 800m grid cell resolution for precipitation, mean, min and max 
#'   temperature
#' 
#' @param resolution The spatial resolution of the data, must be either "4km" 
#'   or "800m".
#' 
#' @param annual if `TRUE` download annual normals.
#' 
#' @section Normals:
#' 
#' 30-year normals are currently computed using 1991-2020 and are available at 
#' 4km and 800m resolution. See 
#' [https://prism.nacse.org/normals/](https://prism.nacse.org/normals/).
#' If `mon` is specified and `annual` is `TRUE`, then monthly and annual normal 
#' data will be downloaded.
#' 
#' @examples \dontrun{
#' # Get 30 year normal values for January rainfall
#' get_prism_normals(type = "ppt", resolution = "4km", mon = 1, keepZip = FALSE)
#' 
#' # Get monthly (every month) and annual 30-year normals for mean temperature
#' get_prism_normals(
#'   type = "tmean", 
#'   resolution = "800m", 
#'   mon = 1:12, 
#'   annual = TRUE,
#'   keepZip = FALSE
#' )
#' }
#' 
#' @rdname get_prism_data
#' 
#' @export
get_prism_normals <- function(type, resolution, mon = NULL, annual = FALSE,  
                              keepZip = TRUE)
{
  ### parameter and error handling
  prism_check_dl_dir()
  type <- match.arg(type, prism_vars())
  resolution <- match.arg(resolution, c("4km","800m"))
  
  if (is.null(mon) & !annual) {
    stop(
      "`mon` is `NULL` and `annual` is `FALSE`.\n",
      "Specify either monthly or/and annual data to download."
    )
  }
  
  call_mon <- c()
  if(!is.null(mon)){
    if(any(mon < 1 | mon > 12)) {
      stop("You must enter a month between 1 and 12")
    }
    call_mon <- mon_to_string(mon)
  } 
  
  if (annual) {
    call_mon <- c(call_mon, "14")
  }
 
  stemp <- "http://services.nacse.org/prism/data/public/normals"
  uris <- gen_prism_url(call_mon, type, stemp, resolution) 

  mpb <- txtProgressBar(min = 0, max =length(uris), style = 3)
 
  for(i in seq_along(uris)){
    prism_webservice(uris[i],keepZip)
    setTxtProgressBar(mpb, i)
    
  }
  
  close(mpb)
}