>>> df = DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
>>>                         'foo', 'bar', 'foo', 'foo'],
...                  'B' : ['one', 'one', 'two', 'three',
...                         'two', 'two', 'one', 'three'],
...                  'C' : randn(8), 'D' : randn(8)})
>>> grouped = df.groupby('A')
>>> grouped

>>> test = grouped.aggregate(np.sum)
>>> test
            C         D
A                      
bar -1.852376  2.204224
foo -3.398196 -0.045082