store safe_cast_to_index call to avoid double call

pydata · Mar 31, 2020 · 4407f40 · 4407f40
1 parent fdeffd9
commit 4407f40
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/xarray/core/groupby.py b/xarray/core/groupby.py
@@ -370,11 +370,12 @@ def __init__(
                 group = group.dropna(group_dim)
 
             # look through group to find the unique values
+            group_as_index = safe_cast_to_index(group)
             sort = bins is None and (
-                not isinstance(safe_cast_to_index(group), pd.MultiIndex)
+                not isinstance(group_as_index, pd.MultiIndex)
             )
             unique_values, group_indices = unique_value_groups(
-                safe_cast_to_index(group), sort=sort
+                group_as_index, sort=sort
             )
             unique_coord = IndexVariable(group.name, unique_values)