ADD: Add gridding ability to xradar radar object (#1719)

pyart/xradar/accessor.py

@@ -345,11 +345,22 @@ def __init__(self, xradar, default_sweep="sweep_0", scan_type=None):
         self.ngates = len(self.range["data"])
         self.nrays = len(self.azimuth["data"])
         self.projection = {"proj": "pyart_aeqd", "_include_lon_0_lat_0": True}
+        self.sweep_number = {
+            "standard_name": "sweep_number",
+            "long_name": "Sweep number",
+            "data": np.unique(self.combined_sweeps.sweep_number),
+        }
+        self.sweep_mode = self._determine_sweep_mode()
         self.instrument_parameters = self.find_instrument_parameters()
         self.init_gate_x_y_z()
         self.init_gate_longitude_latitude()
         self.init_gate_alt()
 
+        # Extra methods needed for compatibility
+        self.rays_are_indexed = None
+        self.ray_angle_res = None
+        self.target_scan_rate = None
+
     def __repr__(self):
         return formatting.datatree_repr(self.xradar)
 
@@ -392,6 +403,24 @@ def __getitem__(self: DataTree, key):
 
         # Iterators
 
+    def _determine_sweep_mode(self):
+        sweep_mode = {
+            "units": "unitless",
+            "standard_name": "sweep_mode",
+            "long_name": "Sweep mode",
+        }
+        if "sweep_mode" in self.xradar["sweep_0"]:
+            sweep_mode["data"] = np.array(
+                self.nsweeps * [str(self.xradar["sweep_0"].sweep_mode.values)],
+                dtype="S",
+            )
+        else:
+            sweep_mode["data"] = np.array(
+                self.nsweeps * ["azimuth_surveillance"], dtype="S"
+            )
+
+        return sweep_mode
+
     def find_instrument_parameters(self):
         # By default, check the radar_parameters first
         if "radar_parameters" in list(self.xradar.children):

tests/xradar/test_accessor.py

@@ -9,6 +9,14 @@
 filename = DATASETS.fetch("cfrad.20080604_002217_000_SPOL_v36_SUR.nc")
 cfradial2_file = DATASETS.fetch("cfrad2.20080604_002217_000_SPOL_v36_SUR.nc")
 
+COMMON_MAP_TO_GRID_ARGS = {
+    "grid_shape": (3, 9, 10),
+    "grid_limits": ((-400.0, 400.0), (-900.0, 900.0), (-900, 900)),
+    "fields": None,
+    "gridding_algo": "map_to_grid",
+    "roi_func": lambda z, y, x: 30,
+}
+
 
 def test_get_field(filename=filename):
     dtree = xd.io.open_cfradial1_datatree(
@@ -209,3 +217,14 @@ def test_cfradial2_data():
     # Ensure georeferencing works as expected
     x, y, z = radar.get_gate_x_y_z(0)
     assert x.shape == (480, 996)
+
+
+def test_grid_xradar():
+    dtree = xd.io.open_cfradial1_datatree(
+        filename,
+        optional=False,
+    )
+    radar = dtree.pyart.to_radar()
+    grid = pyart.map.grid_from_radars([radar], **COMMON_MAP_TO_GRID_ARGS)
+    assert (10, 9, 3) == (grid.nx, grid.ny, grid.nz)
+    assert_allclose(np.min(grid.fields["DBZ"]["data"]), -1.3201784)