`SeriesGroupBy.agg` does not accept `Aggregate`s when passed as kwargs about dask HOT 3 OPEN

@flying-sheep, thanks for creating this issue. Please provide a minimal reproducer (see http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports for guidelines) to allow us to investigate your problem.

from dask.

Not really necessary, you can directly see the problem in the linked line, but sure.

import pandas as pd
import dask.dataframe as dd

custom_sum = dd.Aggregation(
    name='custom_sum',
    chunk=lambda s: s.sum(),
    agg=lambda s0: s0.sum()
)

df = pd.DataFrame(dict(a=[1, 1, 1, 1, 1], g=[5, 6, 6, 6, 7]))
ddf = dd.from_pandas(df, npartitions=2)

ddf.groupby('g')['a'].agg(sum="sum").compute()  # works
ddf.groupby('g')['a'].agg(sum=custom_sum).compute()  # broken

from dask.

Thanks for adding the reproducer! Please keep in mind that the time of contributors is limited, so having a reproducer ready allows us to move more quickly. It is also a great starting point for a regression test.

from dask.