Expose top-level xarray.indexes in __init__

Also expose CoordinateTransformIndex

Closes #10424

Author: dcherian

xarray/__init__.py

@@ -1,6 +1,6 @@
 from importlib.metadata import version as _version
 
-from xarray import coders, groupers, testing, tutorial, ufuncs
+from xarray import coders, groupers, indexes, testing, tutorial, ufuncs
 from xarray.backends.api import (
     load_dataarray,
     load_dataset,
@@ -70,6 +70,7 @@
     # Sub-packages
     "coders",
     "groupers",
+    "indexes",
     "testing",
     "tutorial",
     "ufuncs",

xarray/indexes/__init__.py

@@ -4,10 +4,17 @@
 """
 
 from xarray.core.indexes import (
+    CoordinateTransformIndex,
     Index,
     PandasIndex,
     PandasMultiIndex,
 )
 from xarray.indexes.range_index import RangeIndex
 
-__all__ = ["Index", "PandasIndex", "PandasMultiIndex", "RangeIndex"]
+__all__ = [
+    "CoordinateTransformIndex",
+    "Index",
+    "PandasIndex",
+    "PandasMultiIndex",
+    "RangeIndex",
+]