Pandas Groupby Agg Function Does Not Reduce

Question

I am using an aggregation function that I have used in my work for a long time now. The idea is that if the Series passed to the function is of length 1 (i.e. the group only

Answer 1

I can't really explain you why, but from my experience list in pandas.DataFrame don't work all that well.

I usually use tuple instead. That will work:

def MakeList(x):
    T = tuple(x)
    if len(T) > 1:
        return T
    else:
        return T[0]

DF_Agg = DFGrouped.agg({'s.m.v.' : MakeList})

     date line_code           s.m.v.
0  2013-04-02    401101   (7.76, 25.564)
1  2013-04-02    401102           25.564
2  2013-04-02    401103             9.55
3  2013-04-02    401104             4.87
4  2013-04-02    401105   (7.76, 25.564)
5  2013-04-02    401106  (5.282, 25.564)
6  2013-04-02    401107            5.282