Add NDPointIndex (KDTree) (#10478)

Co-authored-by: Deepak Cherian <dcherian@users.noreply.github.com>

Author: benbovy

doc/api.rst

@@ -1577,6 +1577,7 @@ Custom Indexes
    CFTimeIndex
    indexes.RangeIndex
    indexes.CoordinateTransformIndex
+   indexes.NDPointIndex
 
 Creating custom indexes
 -----------------------

doc/whats-new.rst

@@ -56,6 +56,9 @@ New Features
 
 - Expose :py:class:`~xarray.indexes.RangeIndex`, and :py:class:`~xarray.indexes.CoordinateTransformIndex` as public api
   under the ``xarray.indexes`` namespace. By `Deepak Cherian <https://github.com/dcherian>`_.
+- New :py:class:`xarray.indexes.NDPointIndex`, which by default uses :py:class:`scipy.spatial.KDTree` under the hood for
+  the selection of irregular, n-dimensional data (:pull:`10478`).
+  By `Benoit Bovy <https://github.com/benbovy>`_.
 - Support zarr-python's new ``.supports_consolidated_metadata`` store property (:pull:`10457``).
   by `Tom Nicholas <https://github.com/TomNicholas>`_.
 - Better error messages when encoding data to be written to disk fails (:pull:`10464`).

xarray/core/coordinate_transform.py

@@ -80,7 +80,7 @@ def equals(self, other: CoordinateTransform, **kwargs) -> bool:
         Parameters
         ----------
         other : CoordinateTransform
-            The other Index object to compare with this object.
+            The other CoordinateTransform object to compare with this object.
         exclude : frozenset of hashable, optional
             Dimensions excluded from checking. It is None by default, (i.e.,
             when this method is not called in the context of alignment). For a

xarray/indexes/__init__.py

@@ -10,12 +10,14 @@
     PandasIndex,
     PandasMultiIndex,
 )
+from xarray.indexes.nd_point_index import NDPointIndex
 from xarray.indexes.range_index import RangeIndex
 
 __all__ = [
     "CoordinateTransform",
     "CoordinateTransformIndex",
     "Index",
+    "NDPointIndex",
     "PandasIndex",
     "PandasMultiIndex",
     "RangeIndex",