Read NetCDF-CF spatial geometries — read

Attempts to convert a NetCDF-CF DSG Simple Geometry file into a sf data.frame.

read_geometry(nc_file)

Arguments

nc_file: character file path to the nc file to be read.

Value

sf data.frame containing spatial geometry of type found in the NetCDF-CF DSG file.

References

http://cfconventions.org/index.html

http://cfconventions.org/cf-conventions/cf-conventions.html#_features_and_feature_types

Examples

huc_eta_nc <- tempfile()
file.copy(system.file('extdata','example_huc_eta.nc', package = 'ncdfgeom'), 
         huc_eta_nc, overwrite = TRUE)
#> [1] TRUE
         
vars <- ncmeta::nc_vars(huc_eta_nc)

hucPolygons <- sf::read_sf(system.file('extdata','example_huc_eta.json', package = 'ncdfgeom'))
plot(sf::st_geometry(hucPolygons))

names(hucPolygons)
#>  [1] "TNMID"      "METASOURCE" "SOURCEDATA" "SOURCEORIG" "SOURCEFEAT"
#>  [6] "LOADDATE"   "GNIS_ID"    "AREAACRES"  "AREASQKM"   "STATES"    
#> [11] "HUC12"      "NAME"       "HUTYPE"     "HUMOD"      "TOHUC"     
#> [16] "NONCONTRIB" "NONCONTR_1" "SHAPE_Leng" "SHAPE_Area" "geometry"  

hucPolygons_nc <- ncdfgeom::write_geometry(nc_file=huc_eta_nc, 
                                          geom_data = hucPolygons, 
                                          instance_dim_name = "station", 
                                          variables = vars$name)
huc_poly <- read_geometry(huc_eta_nc)
plot(sf::st_geometry(huc_poly))

names(huc_poly)
#>  [1] "lat"          "lon"          "station_name" "TNMID"        "METASOURCE"  
#>  [6] "SOURCEDATA"   "SOURCEORIG"   "SOURCEFEAT"   "LOADDATE"     "GNIS_ID"     
#> [11] "AREAACRES"    "AREASQKM"     "STATES"       "HUC12"        "NAME"        
#> [16] "HUTYPE"       "HUMOD"        "TOHUC"        "NONCONTRIB"   "NONCONTR_1"  
#> [21] "SHAPE_Leng"   "SHAPE_Area"   "geom"