Exemplo:
In [63]: df
Out[63]:
a b c
0 1 [1, 2, 3] foo
1 1 [2, 5] bar
2 2 [5, 6] baz
In [64]: df.groupby('a').agg({'b': 'sum', 'c': lambda x: ' '.join(x)})
Out[64]:
c b
a
1 foo bar [1, 2, 3, 2, 5]
2 baz [5, 6]Isso agrupa o quadro de dados pelos valores na coluna a. Leia mais sobre o [groupby] ( http://pandas.pydata.org/pandas-docs/stable/groupby.html ).
Referencia: https://stackoverflow.com/questions/23794082/pandas-groupby-and-join-lists