neighbour operations

xdggs/grid.py

@@ -42,6 +42,9 @@ def cell_boundaries(self, cell_ids, backend="shapely"):
     def zoom_to(self, cell_ids, level: int):
         raise NotImplementedError()
 
+    def neighbours(self, cell_ids, ring=1):
+        raise NotImplementedError()
+
 
 def translate_parameters(mapping, translations):
     def translate(name, value):

xdggs/h3.py

@@ -7,14 +7,14 @@
 import xarray as xr
 
 try:
-    from h3ronpy import change_resolution
+    from h3ronpy import change_resolution, grid_disk
     from h3ronpy.vector import (
         cells_to_coordinates,
         cells_to_wkb_polygons,
         coordinates_to_cells,
     )
 except ImportError:
-    from h3ronpy.arrow import change_resolution
+    from h3ronpy.arrow import change_resolution, grid_disk
     from h3ronpy.arrow.vector import (
         cells_to_coordinates,
         cells_to_wkb_polygons,
@@ -205,6 +205,11 @@ def zoom_to(self, cell_ids, level):
 
         return np.asarray(change_resolution(cell_ids, level))
 
+    def neighbours(self, cell_ids, ring=1):
+        neighbours = grid_disk(cell_ids, k=ring, flatten=False)
+
+        return neighbours
+
 
 @register_dggs("h3")
 class H3Index(DGGSIndex):

xdggs/healpix.py

@@ -322,6 +322,11 @@ def zoom_to(self, cell_ids, level):
 
         return zoom_to(cell_ids, self.level, level)
 
+    def neighbours(self, cell_ids, ring=1):
+        from healpix_geo.nested import kth_neighbourhood
+
+        return kth_neighbourhood(cell_ids, depth=self.level, ring=ring)
+
 
 def construct_chunk_ranges(chunks, until):
     start = 0