code sample for pandas-dev#43209

Author: simonjayhawkins

bisect/43209.py

@@ -0,0 +1,18 @@
+# BUG: groupby aggregation methods produce empty DataFrame with mixed DataTypes #43209
+
+import pandas as pd
+
+print(pd.__version__)
+
+
+df = pd.DataFrame([[1, 2, 3, 4, 5, 6]] * 3)
+df.columns = pd.MultiIndex.from_product([["a", "b"], ["i", "j", "k"]])
+
+for col in df.columns:
+    if col[-1] == "j":
+        df[col] = df[col].astype("Int64")
+
+result = df.groupby(level=1, axis=1).sum()
+print(result)
+
+assert len(result)