Added __getattr__ in DataFrameGroupBy

[ramvikrams]

• Closes DataFrameGroupBy attribute access for columns #439 (Replace xxxx with the Github issue number)
• Tests added: Please use assert_type() to assert the type of any return value
  the error is saying expected Series but got SeriesGroupBy, I can't understand it

Sorry sir forgot to add the correct commit file name.

[Dr-Irv]

This should be SeriesGroupBy

>>> df = pd.DataFrame(
...         {
...             'C': [1, 5, 5, 2, 5, 5],
...             'D': [2.0, 5.0, 8.0, 1.0, 2.0, 9.0],
...         }
...     )
>>> gb = df.groupby('C').D
>>> gb
<pandas.core.groupby.generic.SeriesGroupBy object at 0x000002E6ED25CA00>

[ramvikrams]

Done sir

[Dr-Irv]

This should be SeriesGroupBy

[Dr-Irv]

I think I would prefer a test that does not import SeriesGroupBy because that is not a documented class.

Borrowing from lines 669, but modified to test the getattr:

    df = pd.DataFrame(
        data={"col1": [1, 1, 2], "col2": [3, 4, 5], "col3": [0, 1, 0], 0: [-1, -1, -1]}
    )
    check(assert_type(df.groupby("col1").col3.agg(min), pd.Series), pd.Series)
    check(
        assert_type(df.groupby("col1").col3.agg([min, max]), pd.DataFrame),
        pd.DataFrame,
    )

[ramvikrams]

i'll do that sir

[ramvikrams]

Sir I am failing to understand that even if we write tests check(assert_type((df.groupby("C").__getattr__("D")), pd.Series), pd.Series) like this, how will it change because the return type of __getattr__ will still be SeriesGroupBy

[Dr-Irv]

The idea is that you are not testing __getattr__() directly, but indirectly, because you always use a method in SeriesGroupBy in real code. The example I gave is calling agg() on the SeriesGroupBy result. Both df.groupby("col1").col3 and df.groupby("col1")["col3"] return a SeriesGroupBy object.

See the test test_types_groupby_agg for an example where we use the second form, which is where I copied this from.

[ramvikrams]

sir I read the test_types_groupby_agg but here when I give the str to __getattr__() the error is there about expected series but got seriesgroupby pushing a commit so you can also check

[Dr-Irv]

Please implement the test as I wrote above.

[ramvikrams]

I did try it this way it shows AttributeError: 'SeriesGroupBy' object has no attribute 'col2' but this error should not be reported

[Dr-Irv]

Please follow instructions precisely

[Dr-Irv]

This should be SeriesGroupBy

[Dr-Irv]

This test should be the same as #457 (comment)

[ramvikrams]

Done

[Dr-Irv]

thanks @ramvikrams

[ramvikrams]

thanks @ramvikrams

Thanks sir