DOC: DataFrame.groupy.agg with a list of tuples

[tdpetrou]

Code Sample, a copy-pastable example if possible

>>> df = pd.DataFrame({'key' : ['a', 'a', 'b', 'b', 'a'],
                       'data' : np.random.randn(5)})

>>> df.groupby('key')['data'].agg([('foo', 'mean')])
          foo
key          
a   -0.944872
b    0.893212

Problem description

I know its deprecated to rename columns with a dictionary of dictionaries in a groupby but a list of tuples also renames columns.

This behavior is not found in the docs. I accidentally discovered this a while back and then saw it again in Python for Data Analysis.

[rhshadrach]

Confirmed this is tested in test_multiple_functions_tuples_and_non_tuples. The documentation could go in https://pandas.pydata.org/pandas-docs/dev/user_guide/groupby.html#named-aggregation

[Ememobong28]

take