Typing of GroupBy & Co. (#6702)

Co-authored-by: Illviljan <[email protected]>
Co-authored-by: Deepak Cherian <[email protected]>

Author: 3 people

doc/whats-new.rst

@@ -26,6 +26,10 @@ New Features
   :py:meth:`DataArrayCoordinates.dtypes` properties: Mapping from variable names to dtypes.
   (:pull:`6706`)
   By `Michael Niklas <https://github.com/headtr1ck>`_.
+- Initial typing support for :py:meth:`groupby`, :py:meth:`rolling`, :py:meth:`rolling_exp`,
+  :py:meth:`coarsen`, :py:meth:`weighted`, :py:meth:`resample`,
+  (:pull:`6702`)
+  By `Michael Niklas <https://github.com/headtr1ck>`_.
 
 Deprecations
 ~~~~~~~~~~~~

xarray/core/alignment.py

@@ -215,7 +215,7 @@ def _normalize_indexes(
         normalized_index_vars = {}
         for idx, index_vars in Indexes(xr_indexes, xr_variables).group_by_index():
             coord_names_and_dims = []
-            all_dims = set()
+            all_dims: set[Hashable] = set()
 
             for name, var in index_vars.items():
                 dims = var.dims