[madenine]

you can supply a map, ie:

gdf = df.groupby('col1').agg({'col2': np.mean, 'col3':np.std,'col4': lamba x: np.mean((x) / np.std(x))})

once you've got your grouped dataframe, go nuts

gdf['some_name'] = gdf['col1'].apply(f1) + gdf['col2'].apply(f2)

[closed]

The summarise example I gave creates a single new column (some_col), that is a function of two columns from the grouped data frame. Passing a map to agg is just creating multiple columns, each a function of at most a single column in the dataframe.

(I should have used a better example, like summarise(gdf, some_col = f(cola / colb))