In [2]: df = pd.DataFrame({"A": [1, 2, 1, 2], "B": [1, 2, 3, 4]}) In [3]: df Out[3]: A B 0 1 1 1 2 2 2 1 3 3 2 4 In [4]: df.agg(foo=("B", "sum"))

In [13]: df.agg({"B": {"foo": "sum"}}) /Users/taugspurger/Envs/dask-dev/lib/python3.7/site-packages/pandas/core/frame.py:6284: FutureWarning: using a dict with renaming is deprecated and will be removed in a future version result, how = self._aggregate(func, axis=axis, *args, **kwargs) Out[13]: B foo 10

In [16]: df.B.agg({"foo": "sum"}) # allow foo="sum" Out[16]: foo 10 Name: B, dtype: int64