code sample for pandas-dev#46496

Author: simonjayhawkins

bisect/46496.py

@@ -0,0 +1,21 @@
+# BUG: lambda with positional references in apply after groupby on empty dataframe errors #46496
+
+import pandas as pd
+
+print(pd.__version__)
+
+
+result = (
+    pd.DataFrame([], columns=["a", "b", "c"])
+    .groupby("a")
+    .b.apply(lambda x: x[0] - x[1])
+)
+print(repr(result))
+
+expected = pd.Series(
+    [],
+    name="b",
+    dtype=object,
+    index=pd.Index([], dtype="object", name="a"),
+)
+pd.testing.assert_series_equal(result, expected)