Grouper refactor (#9122)

* Move Groupers out to groupers.py

* cleanup

* missed one.

Author: dcherian

xarray/core/common.py

@@ -1067,7 +1067,8 @@ def _resample(
         # TODO support non-string indexer after removing the old API.
 
         from xarray.core.dataarray import DataArray
-        from xarray.core.groupby import ResolvedGrouper, TimeResampler
+        from xarray.core.groupby import ResolvedGrouper
+        from xarray.core.groupers import TimeResampler
         from xarray.core.resample import RESAMPLE_DIM
 
         # note: the second argument (now 'skipna') use to be 'dim'

xarray/core/dataarray.py

@@ -6751,9 +6751,9 @@ def groupby(
         from xarray.core.groupby import (
             DataArrayGroupBy,
             ResolvedGrouper,
-            UniqueGrouper,
             _validate_groupby_squeeze,
         )
+        from xarray.core.groupers import UniqueGrouper
 
         _validate_groupby_squeeze(squeeze)
         rgrouper = ResolvedGrouper(UniqueGrouper(), group, self)
@@ -6833,11 +6833,11 @@ def groupby_bins(
         .. [1] http://pandas.pydata.org/pandas-docs/stable/generated/pandas.cut.html
         """
         from xarray.core.groupby import (
-            BinGrouper,
             DataArrayGroupBy,
             ResolvedGrouper,
             _validate_groupby_squeeze,
         )
+        from xarray.core.groupers import BinGrouper
 
         _validate_groupby_squeeze(squeeze)
         grouper = BinGrouper(

xarray/core/dataset.py

@@ -10301,9 +10301,9 @@ def groupby(
         from xarray.core.groupby import (
             DatasetGroupBy,
             ResolvedGrouper,
-            UniqueGrouper,
             _validate_groupby_squeeze,
         )
+        from xarray.core.groupers import UniqueGrouper
 
         _validate_groupby_squeeze(squeeze)
         rgrouper = ResolvedGrouper(UniqueGrouper(), group, self)
@@ -10384,11 +10384,11 @@ def groupby_bins(
         .. [1] http://pandas.pydata.org/pandas-docs/stable/generated/pandas.cut.html
         """
         from xarray.core.groupby import (
-            BinGrouper,
             DatasetGroupBy,
             ResolvedGrouper,
             _validate_groupby_squeeze,
         )
+        from xarray.core.groupers import BinGrouper
 
         _validate_groupby_squeeze(squeeze)
         grouper = BinGrouper(