python中operator.itemgetter

直接上例子：

rs=  [
...     {
...       "datetime": "Mon, 31 Aug 2015 23:00:00 GMT",
...       "id": 1,
...       "name":"a"
...     },
...     {
...       "datetime": "Mon, 31 Aug 2015 23:00:00 GMT",
...       "id": 2,
...       "name":"b"
...     },
...     {
...       "datetime": "Mon, 31 Aug 2015 23:00:00 GMT",
...       "id": 3,
...       "name":"c"
...     },
...     {
...       "datetime": "Mon, 31 Aug 2015 23:00:00 GMT",
...       "id": 4,
...       "name":"d"
...     }
... ]

 fun = operator.itemgetter('id', 'name')

for key, g in itertools.groupby(rs, fun):
...     print key
...     print g
...
(1, 'a')
<itertools._grouper object at 0x7f07e9623650>
(2, 'b')
<itertools._grouper object at 0x7f07e96236d0>
(3, 'c')
<itertools._grouper object at 0x7f07e9623650>