code sample for pandas-dev#43132

Author: simonjayhawkins

bisect/43132.py

@@ -0,0 +1,14 @@
+# BUG: timeseries.groupby(...).transform('mean') wrong when aggregating over pd.NaT #43132
+
+import pandas as pd
+
+print(pd.__version__)
+
+s = pd.Series(["1 day", "3 days", pd.NaT], dtype="timedelta64[ns]")
+grp = s.groupby([1, 1, 1])
+try:
+    result = grp.transform("mean")
+    print(result)
+    assert False
+except pd.core.base.DataError as e:
+    print(e)