Examples.md

@@ -618,3 +618,112 @@ r <- Compute(wf,
 </p>
 </details>
 
+## Interpolation in Start()
+<details><summary>CLICK ME</summary>
+</p>
+<br/>
+
+Do the interpolation within Start(), and compare with Load() result. When the Start() parameter `transform_extra_cells = 2`, the two results will be the same.
+
+```r
+# ------------------------------------------------------------------
+# Do the interpolation within Start(). Compare with Load().
+# ------------------------------------------------------------------
+
+library(startR)
+library(s2dverification)
+
+obs_path <- '/esarchive/recon/ecmwf/era5/monthly_mean/$var$_f1h/$var$_$sdate$.nc'
+pobs <- paste0('/esarchive/recon/ecmwf/era5/monthly_mean/',
+               '$VAR_NAME$_f1h/$VAR_NAME$_$YEAR$$MONTH$.nc')
+var_name<-'sfcWind'
+
+lons.min <- 0
+lons.max <- 10
+lats.min <- 0
+lats.max <- 10
+
+#-------------------------
+# Start()
+#-------------------------
+obs <- Start(dat = obs_path,
+             var = var_name,
+             sdate = '201811',
+             time = 'all',
+             latitude = values(list(lats.min, lats.max)),
+             latitude_reorder = Sort(),
+             longitude = values(list(lons.min, lons.max)),
+             synonims = list(longitude = c('lon', 'longitude'),
+                             latitude = c('lat', 'latitude')),
+             transform = CDORemapper,
+             transform_extra_cells = 2,
+             transform_params = list(grid = 'r360x181',
+                                     method = 'conservative',
+                                     crop = c(lons.min, lons.max, lats.min, lats.max)), 
+             transform_vars = c('latitude', 'longitude'),
+             return_vars = list(time = NULL,
+                                latitude = 'dat',
+                                longitude = 'dat'),
+             split_multiselected_dims = TRUE,
+             merge_across_dims = TRUE,
+             #num_procs = 4,
+             retrieve = T)
+
+# -- Result --
+dim(obs)
+#      dat       var     sdate      time  latitude longitude 
+#        1         1         1         1        11        11 
+range(obs)
+#[1] 1.090472 4.987585
+str(attr(obs, 'Variables')$common[[var_name]]$dim[[1]])
+# $ name         : chr "longitude"
+# $ vals         : num [1:11(1d)] 0 1 2 3 4 5 6 7 8 9 ...
+str(attr(obs, 'Variables')$common[[var_name]]$dim[[2]])
+# $ name         : chr "latitude"
+# $ vals         : num [1:11(1d)] 0 1 2 3 4 5 6 7 8 9 ...
+obs[1,1,1,1,,1]
+# [1] 4.987585 4.299388 4.007287 3.758497 3.673881 3.908989 2.224407 1.774090
+# [9] 1.800998 1.718733 1.816074
+
+#-------------------------
+# s2dverification::Load()
+#-------------------------
+obs1 <- Load(var = var_name,
+             obs = list(list(path = pobs)),
+             sdates = '20181101',
+             leadtimemin = 1,
+             leadtimemax = 1,
+             output = 'lonlat',
+             grid = 'r360x181',
+             method = 'conservative',
+             storefreq = 'monthly',
+             latmin = lats.min,
+             latmax = lats.max,
+             lonmin = lons.min,
+             lonmax = lons.max)
+
+# -- Result --
+dim(obs1$obs)
+#dataset  member   sdate   ftime     lat     lon 
+#      1       1       1       1      11      11 
+range(obs1$obs)
+#[1] 1.0905 4.9876
+str(obs1)
+# $ lon            : num [1:11(1d)] 0 1 2 3 4 5 6 7 8 9 ...
+# $ lat            : num [1:11(1d)] 10 9 8 7 6 5 4 3 2 1 ...
+obs1$obs[1,1,1,1,,1]  #when lon = 0
+# [1] 1.8161 1.7187 1.8010 1.7741 2.2244 3.9090 3.6739 3.7585 4.0073 4.2994
+#[11] 4.9876
+
+
+#-----------------------
+# Comparison
+#-----------------------
+diff <- drop(obs)[11:1, ] - drop(obs1$obs)  #lat order is different
+range(diff)
+#[1] -4.918404e-05  4.693756e-05
+
+```
+
+</p>
+</details>
\ No newline at end of file