code sample for pandas-dev#45231

Author: simonjayhawkins

bisect/45231.py

@@ -0,0 +1,17 @@
+# BUG: 1.4.0rc1 Error vectorizing grouping aggregation on empty dataframe with object column #45231
+
+import pandas as pd
+
+print(pd.__version__)
+
+df = pd.DataFrame(
+    {"group": pd.Series(dtype="object"), "str": pd.Series(dtype="object")}
+)
+
+result = df.groupby("group").any()
+print(result)
+
+expected = pd.DataFrame(
+    {"str": pd.Series([], dtype=bool)}, index=pd.Index([], dtype="object", name="group")
+)
+pd.testing.assert_frame_equal(result, expected)