feat: stations_elevation() using read_fwf

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: GHCNr
 Title: Download Weather Station Data from GHCN
-Version: 1.2.0
+Version: 1.3.0
 Authors@R: 
     person("Emilio", "Berti", , "emilio.berti@idiv.de", role = c("aut", "cre"),
            comment = c(ORCID = "0000-0001-9286-011X"))

NAMESPACE

@@ -27,6 +27,7 @@ export(as_daily)
 export(coverage)
 export(daily)
 export(download_inventory)
+export(elevation_stations)
 export(filter_stations)
 export(get_countries)
 export(get_country)
@@ -71,6 +72,8 @@ importFrom(httr2,request)
 importFrom(httr2,resp_body_json)
 importFrom(httr2,resp_status)
 importFrom(httr2,resp_status_desc)
+importFrom(readr,fwf_positions)
+importFrom(readr,read_fwf)
 importFrom(readr,read_table)
 importFrom(rlang,.data)
 importFrom(stats,interaction.plot)

R/data.R

@@ -37,14 +37,3 @@
 #' }
 #' @source <https://www.countrycallingcodes.com/iso-country-codes/europe-codes.php>
 "USC00010655"
-
-#' Elevation of the GHCNd Stations
-#'
-#' @format ## `europe_codes`
-#' A table 128,024 x 2:
-#' \describe{
-#'   \item{station}{Station name}
-#'   \item{elevation}{Elevation in meters}
-#' }
-#' @source <https://www.ncei.noaa.gov/pub/data/ghcn/daily/ghcnd-stations.csv>
-"stations_elevation"

R/elevation.R

@@ -0,0 +1,38 @@
+#' @title The GHCNd Station URL with Elevation
+#' @return The URL of the GHCNd stations.
+.elevation_url <- function() {
+  return("https://www.ncei.noaa.gov/pub/data/ghcn/daily/ghcnd-stations.txt")
+}
+
+#' @title Get GHCNd Station Elevation
+#'
+#' @importFrom readr read_fwf fwf_positions
+#' @importFrom curl has_internet
+#'
+#' @export
+#'
+#' @return The table with the elevation of GHCNd stations.
+#' 
+#' @examples
+#' \dontrun{
+#' el <- elevation_stations()
+#' }
+elevation_stations <- function() {
+  if (!has_internet()) stop("You do not have access to the internet. Check you connection and try again.")
+
+  ans <- tryCatch(
+    read_fwf(.elevation_url(),
+      fwf_positions(
+        start = c(1, 32),
+        end = c(11, 38),
+        col_names = c("station", "elevation")
+      ),
+      col_types = "cd"
+    ),
+    error = function(e) message(errorCondition(e))
+  )
+  if (is.null(ans)) stop(.elevation_url(), " not found.")
+
+  return(ans)
+
+}