Fix binning when labels are provided. (#7205)

Closes #7198

Author: dcherian

xarray/core/groupby.py

@@ -771,10 +771,7 @@ def _flox_reduce(
             # the bin edge labels have a default precision of 3
             # reassign to fix that.
             assert self._full_index is not None
-            new_coord = [
-                pd.Interval(inter.left, inter.right) for inter in self._full_index
-            ]
-            result[self._group.name] = new_coord
+            result[self._group.name] = self._full_index
             # Fix dimension order when binning a dimension coordinate
             # Needed as long as we do a separate code path for pint;
             # For some reason Datasets and DataArrays behave differently!

xarray/tests/test_groupby.py

@@ -1370,6 +1370,9 @@ def test_groupby_bins(self):
         actual = array.groupby_bins("dim_0", bins=bins).sum()
         assert_identical(expected, actual)
 
+        actual = array.groupby_bins("dim_0", bins=bins, labels=[1.2, 3.5]).sum()
+        assert_identical(expected.assign_coords(dim_0_bins=[1.2, 3.5]), actual)
+
         actual = array.groupby_bins("dim_0", bins=bins).map(lambda x: x.sum())
         assert_identical(expected, actual)