Expand use of .oindex and .vindex (#8790)

* refactor __getitem__() by removing vectorized and orthogonal indexing logic from it

* implement explicit routing of vectorized and outer indexers

* Add VectorizedIndexer and OuterIndexer to ScipyArrayWrapper's __getitem__ method

* Refactor indexing in LazilyIndexedArray and LazilyVectorizedIndexedArray

* Add vindex and oindex methods to StackedBytesArray

* handle explicitlyindexed arrays

* Refactor LazilyIndexedArray and LazilyVectorizedIndexedArray classes

* Remove TODO comments in indexing.py

* use indexing.explicit_indexing_adapter() in scipy backend

* update docstring

* fix docstring

* Add _oindex_get and _vindex_get methods to NativeEndiannessArray and BoolTypeArray

* Update indexing support in ScipyArrayWrapper

* Update xarray/tests/test_indexing.py

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

* Fix assert statement in test_decompose_indexers

* add comments to clarifying why the else branch is needed

* Add _oindex_get and _vindex_get methods to _ElementwiseFunctionArray

* update whats-new

* Refactor apply_indexer function in indexing.py and variable.py for code reuse

* cleanup

---------

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

doc/whats-new.rst

@@ -32,6 +32,9 @@ New Features
 - Add the ``.vindex`` property to Explicitly Indexed Arrays for vectorized indexing functionality. (:issue:`8238`, :pull:`8780`)
   By `Anderson Banihirwe <https://github.com/andersy005>`_.
 
+- Expand use of ``.oindex`` and ``.vindex`` properties. (:pull: `8790`)
+  By `Anderson Banihirwe <https://github.com/andersy005>`_ and `Deepak Cherian <https://github.com/dcherian>`_.
+
 Breaking changes
 ~~~~~~~~~~~~~~~~
 

xarray/backends/scipy_.py

@@ -23,7 +23,7 @@
     is_valid_nc3_name,
 )
 from xarray.backends.store import StoreBackendEntrypoint
-from xarray.core.indexing import NumpyIndexingAdapter
+from xarray.core import indexing
 from xarray.core.utils import (
     Frozen,
     FrozenDict,
@@ -63,8 +63,15 @@ def get_variable(self, needs_lock=True):
         ds = self.datastore._manager.acquire(needs_lock)
         return ds.variables[self.variable_name]
 
+    def _getitem(self, key):
+        with self.datastore.lock:
+            data = self.get_variable(needs_lock=False).data
+            return data[key]
+
     def __getitem__(self, key):
-        data = NumpyIndexingAdapter(self.get_variable().data)[key]
+        data = indexing.explicit_indexing_adapter(
+            key, self.shape, indexing.IndexingSupport.OUTER_1VECTOR, self._getitem
+        )
         # Copy data if the source file is mmapped. This makes things consistent
         # with the netCDF4 library by ensuring we can safely read arrays even
         # after closing associated files.

xarray/coding/strings.py

@@ -238,6 +238,12 @@ def shape(self) -> tuple[int, ...]:
     def __repr__(self):
         return f"{type(self).__name__}({self.array!r})"
 
+    def _vindex_get(self, key):
+        return _numpy_char_to_bytes(self.array.vindex[key])
+
+    def _oindex_get(self, key):
+        return _numpy_char_to_bytes(self.array.oindex[key])
+
     def __getitem__(self, key):
         # require slicing the last dimension completely
         key = type(key)(indexing.expanded_indexer(key.tuple, self.array.ndim))

xarray/coding/variables.py

@@ -68,6 +68,12 @@ def __init__(self, array, func: Callable, dtype: np.typing.DTypeLike):
     def dtype(self) -> np.dtype:
         return np.dtype(self._dtype)
 
+    def _oindex_get(self, key):
+        return type(self)(self.array.oindex[key], self.func, self.dtype)
+
+    def _vindex_get(self, key):
+        return type(self)(self.array.vindex[key], self.func, self.dtype)
+
     def __getitem__(self, key):
         return type(self)(self.array[key], self.func, self.dtype)
 
@@ -109,6 +115,12 @@ def __init__(self, array) -> None:
     def dtype(self) -> np.dtype:
         return np.dtype(self.array.dtype.kind + str(self.array.dtype.itemsize))
 
+    def _oindex_get(self, key):
+        return np.asarray(self.array.oindex[key], dtype=self.dtype)
+
+    def _vindex_get(self, key):
+        return np.asarray(self.array.vindex[key], dtype=self.dtype)
+
     def __getitem__(self, key) -> np.ndarray:
         return np.asarray(self.array[key], dtype=self.dtype)
 
@@ -141,6 +153,12 @@ def __init__(self, array) -> None:
     def dtype(self) -> np.dtype:
         return np.dtype("bool")
 
+    def _oindex_get(self, key):
+        return np.asarray(self.array.oindex[key], dtype=self.dtype)
+
+    def _vindex_get(self, key):
+        return np.asarray(self.array.vindex[key], dtype=self.dtype)
+
     def __getitem__(self, key) -> np.ndarray:
         return np.asarray(self.array[key], dtype=self.dtype)
 

xarray/core/indexing.py

@@ -491,6 +491,13 @@ def _oindex_get(self, key):
     def _vindex_get(self, key):
         raise NotImplementedError("This method should be overridden")
 
+    def _check_and_raise_if_non_basic_indexer(self, key):
+        if isinstance(key, (VectorizedIndexer, OuterIndexer)):
+            raise TypeError(
+                "Vectorized indexing with vectorized or outer indexers is not supported. "
+                "Please use .vindex and .oindex properties to index the array."
+            )
+
     @property
     def oindex(self):
         return IndexCallable(self._oindex_get)
@@ -517,7 +524,10 @@ def get_duck_array(self):
 
     def __getitem__(self, key):
         key = expanded_indexer(key, self.ndim)
-        result = self.array[self.indexer_cls(key)]
+        indexer = self.indexer_cls(key)
+
+        result = apply_indexer(self.array, indexer)
+
         if isinstance(result, ExplicitlyIndexed):
             return type(self)(result, self.indexer_cls)
         else:
@@ -577,7 +587,13 @@ def shape(self) -> tuple[int, ...]:
         return tuple(shape)
 
     def get_duck_array(self):
-        array = self.array[self.key]
+        if isinstance(self.array, ExplicitlyIndexedNDArrayMixin):
+            array = apply_indexer(self.array, self.key)
+        else:
+            # If the array is not an ExplicitlyIndexedNDArrayMixin,
+            # it may wrap a BackendArray so use its __getitem__
+            array = self.array[self.key]
+
         # self.array[self.key] is now a numpy array when
         # self.array is a BackendArray subclass
         # and self.key is BasicIndexer((slice(None, None, None),))
@@ -594,12 +610,10 @@ def _oindex_get(self, indexer):
 
     def _vindex_get(self, indexer):
         array = LazilyVectorizedIndexedArray(self.array, self.key)
-        return array[indexer]
+        return array.vindex[indexer]
 
     def __getitem__(self, indexer):
-        if isinstance(indexer, VectorizedIndexer):
-            array = LazilyVectorizedIndexedArray(self.array, self.key)
-            return array[indexer]
+        self._check_and_raise_if_non_basic_indexer(indexer)
         return type(self)(self.array, self._updated_key(indexer))
 
     def __setitem__(self, key, value):
@@ -643,7 +657,13 @@ def shape(self) -> tuple[int, ...]:
         return np.broadcast(*self.key.tuple).shape
 
     def get_duck_array(self):
-        array = self.array[self.key]
+
+        if isinstance(self.array, ExplicitlyIndexedNDArrayMixin):
+            array = apply_indexer(self.array, self.key)
+        else:
+            # If the array is not an ExplicitlyIndexedNDArrayMixin,
+            # it may wrap a BackendArray so use its __getitem__
+            array = self.array[self.key]
         # self.array[self.key] is now a numpy array when
         # self.array is a BackendArray subclass
         # and self.key is BasicIndexer((slice(None, None, None),))
@@ -662,6 +682,7 @@ def _vindex_get(self, indexer):
         return type(self)(self.array, self._updated_key(indexer))
 
     def __getitem__(self, indexer):
+        self._check_and_raise_if_non_basic_indexer(indexer)
         # If the indexed array becomes a scalar, return LazilyIndexedArray
         if all(isinstance(ind, integer_types) for ind in indexer.tuple):
             key = BasicIndexer(tuple(k[indexer.tuple] for k in self.key.tuple))
@@ -706,12 +727,13 @@ def get_duck_array(self):
         return self.array.get_duck_array()
 
     def _oindex_get(self, key):
-        return type(self)(_wrap_numpy_scalars(self.array[key]))
+        return type(self)(_wrap_numpy_scalars(self.array.oindex[key]))
 
     def _vindex_get(self, key):
-        return type(self)(_wrap_numpy_scalars(self.array[key]))
+        return type(self)(_wrap_numpy_scalars(self.array.vindex[key]))
 
     def __getitem__(self, key):
+        self._check_and_raise_if_non_basic_indexer(key)
         return type(self)(_wrap_numpy_scalars(self.array[key]))
 
     def transpose(self, order):
@@ -745,12 +767,13 @@ def get_duck_array(self):
         return self.array.get_duck_array()
 
     def _oindex_get(self, key):
-        return type(self)(_wrap_numpy_scalars(self.array[key]))
+        return type(self)(_wrap_numpy_scalars(self.array.oindex[key]))
 
     def _vindex_get(self, key):
-        return type(self)(_wrap_numpy_scalars(self.array[key]))
+        return type(self)(_wrap_numpy_scalars(self.array.vindex[key]))
 
     def __getitem__(self, key):
+        self._check_and_raise_if_non_basic_indexer(key)
         return type(self)(_wrap_numpy_scalars(self.array[key]))
 
     def transpose(self, order):
@@ -912,10 +935,21 @@ def explicit_indexing_adapter(
     result = raw_indexing_method(raw_key.tuple)
     if numpy_indices.tuple:
         # index the loaded np.ndarray
-        result = NumpyIndexingAdapter(result)[numpy_indices]
+        indexable = NumpyIndexingAdapter(result)
+        result = apply_indexer(indexable, numpy_indices)
     return result
 
 
+def apply_indexer(indexable, indexer):
+    """Apply an indexer to an indexable object."""
+    if isinstance(indexer, VectorizedIndexer):
+        return indexable.vindex[indexer]
+    elif isinstance(indexer, OuterIndexer):
+        return indexable.oindex[indexer]
+    else:
+        return indexable[indexer]
+
+
 def decompose_indexer(
     indexer: ExplicitIndexer, shape: tuple[int, ...], indexing_support: IndexingSupport
 ) -> tuple[ExplicitIndexer, ExplicitIndexer]:
@@ -987,10 +1021,10 @@ def _decompose_vectorized_indexer(
     >>> array = np.arange(36).reshape(6, 6)
     >>> backend_indexer = OuterIndexer((np.array([0, 1, 3]), np.array([2, 3])))
     >>> # load subslice of the array
-    ... array = NumpyIndexingAdapter(array)[backend_indexer]
+    ... array = NumpyIndexingAdapter(array).oindex[backend_indexer]
     >>> np_indexer = VectorizedIndexer((np.array([0, 2, 1]), np.array([0, 1, 0])))
     >>> # vectorized indexing for on-memory np.ndarray.
-    ... NumpyIndexingAdapter(array)[np_indexer]
+    ... NumpyIndexingAdapter(array).vindex[np_indexer]
     array([ 2, 21,  8])
     """
     assert isinstance(indexer, VectorizedIndexer)
@@ -1072,7 +1106,7 @@ def _decompose_outer_indexer(
     ... array = NumpyIndexingAdapter(array)[backend_indexer]
     >>> np_indexer = OuterIndexer((np.array([0, 2, 1]), np.array([0, 1, 0])))
     >>> # outer indexing for on-memory np.ndarray.
-    ... NumpyIndexingAdapter(array)[np_indexer]
+    ... NumpyIndexingAdapter(array).oindex[np_indexer]
     array([[ 2,  3,  2],
            [14, 15, 14],
            [ 8,  9,  8]])
@@ -1395,6 +1429,7 @@ def _vindex_get(self, key):
         return array[key.tuple]
 
     def __getitem__(self, key):
+        self._check_and_raise_if_non_basic_indexer(key)
         array, key = self._indexing_array_and_key(key)
         return array[key]
 
@@ -1450,15 +1485,8 @@ def _vindex_get(self, key):
         raise TypeError("Vectorized indexing is not supported")
 
     def __getitem__(self, key):
-        if isinstance(key, BasicIndexer):
-            return self.array[key.tuple]
-        elif isinstance(key, OuterIndexer):
-            return self.oindex[key]
-        else:
-            if isinstance(key, VectorizedIndexer):
-                raise TypeError("Vectorized indexing is not supported")
-            else:
-                raise TypeError(f"Unrecognized indexer: {key}")
+        self._check_and_raise_if_non_basic_indexer(key)
+        return self.array[key.tuple]
 
     def __setitem__(self, key, value):
         if isinstance(key, (BasicIndexer, OuterIndexer)):
@@ -1499,13 +1527,8 @@ def _vindex_get(self, key):
         return self.array.vindex[key.tuple]
 
     def __getitem__(self, key):
-        if isinstance(key, BasicIndexer):
-            return self.array[key.tuple]
-        elif isinstance(key, VectorizedIndexer):
-            return self.vindex[key]
-        else:
-            assert isinstance(key, OuterIndexer)
-            return self.oindex[key]
+        self._check_and_raise_if_non_basic_indexer(key)
+        return self.array[key.tuple]
 
     def __setitem__(self, key, value):
         if isinstance(key, BasicIndexer):
@@ -1603,7 +1626,8 @@ def __getitem__(
             (key,) = key
 
         if getattr(key, "ndim", 0) > 1:  # Return np-array if multidimensional
-            return NumpyIndexingAdapter(np.asarray(self))[indexer]
+            indexable = NumpyIndexingAdapter(np.asarray(self))
+            return apply_indexer(indexable, indexer)
 
         result = self.array[key]
 

xarray/core/variable.py

@@ -761,12 +761,8 @@ def __getitem__(self, key) -> Self:
         dims, indexer, new_order = self._broadcast_indexes(key)
         indexable = as_indexable(self._data)
 
-        if isinstance(indexer, OuterIndexer):
-            data = indexable.oindex[indexer]
-        elif isinstance(indexer, VectorizedIndexer):
-            data = indexable.vindex[indexer]
-        else:
-            data = indexable[indexer]
+        data = indexing.apply_indexer(indexable, indexer)
+
         if new_order:
             data = np.moveaxis(data, range(len(new_order)), new_order)
         return self._finalize_indexing_result(dims, data)
@@ -791,6 +787,7 @@ def _getitem_with_mask(self, key, fill_value=dtypes.NA):
         dims, indexer, new_order = self._broadcast_indexes(key)
 
         if self.size:
+
             if is_duck_dask_array(self._data):
                 # dask's indexing is faster this way; also vindex does not
                 # support negative indices yet:
@@ -800,14 +797,8 @@ def _getitem_with_mask(self, key, fill_value=dtypes.NA):
                 actual_indexer = indexer
 
             indexable = as_indexable(self._data)
+            data = indexing.apply_indexer(indexable, actual_indexer)
 
-            if isinstance(indexer, OuterIndexer):
-                data = indexable.oindex[indexer]
-
-            elif isinstance(indexer, VectorizedIndexer):
-                data = indexable.vindex[indexer]
-            else:
-                data = indexable[actual_indexer]
             mask = indexing.create_mask(indexer, self.shape, data)
             # we need to invert the mask in order to pass data first. This helps
             # pint to choose the correct unit

xarray/tests/test_coding_strings.py

@@ -181,7 +181,7 @@ def test_StackedBytesArray_vectorized_indexing() -> None:
 
     V = IndexerMaker(indexing.VectorizedIndexer)
     indexer = V[np.array([[0, 1], [1, 0]])]
-    actual = stacked[indexer]
+    actual = stacked.vindex[indexer]
     assert_array_equal(actual, expected)