fix example that can give error if 1800UTC forecast is not up yet.

Add date for previous day so that the example may be run at any time.
Previously the example could give an error if the 1800UTC forecast link
was not up yet.

R/gefs.R

@@ -57,8 +57,9 @@
 #' #specific ensemble and times, for the 1800 forecast. 
 #' # here ensembles 1-3 (ensembles are numbered starting with 0)
 #' # and time for 2 days from today at 1800
+#' date=format(as.Date(Sys.time()) - 1, "%Y%m%d")
 #' var = "Temperature_height_above_ground_ens"
-#' gefs(var, lat, lon, forecast_time = "1800", ens_idx=2:4, time_idx=1:8)
+#' gefs(var, lat, lon, date = date, forecast_time = "1800", ens_idx=2:4, time_idx=1:8)
 #' 
 #' #One ensemble, all latitudes and longitudes (this is a big file) for the
 #' # next 3 days.

man/gefs.Rd

@@ -98,8 +98,9 @@ forecast_yesterday_prec = gefs("Total_precipitation_surface_6_Hour_Accumulation_
 #specific ensemble and times, for the 1800 forecast.
 # here ensembles 1-3 (ensembles are numbered starting with 0)
 # and time for 2 days from today at 1800
+date=format(as.Date(Sys.time()) - 1, "\%Y\%m\%d")
 var = "Temperature_height_above_ground_ens"
-gefs(var, lat, lon, forecast_time = "1800", ens_idx=2:4, time_idx=1:8)
+gefs(var, lat, lon, date = date, forecast_time = "1800", ens_idx=2:4, time_idx=1:8)
 
 #One ensemble, all latitudes and longitudes (this is a big file) for the
 # next 3 days.