[求助]关于数组的转换问题

[YIDAY]

现在有这样的数组结构lt1

lt1 = [
    {'goid':1111,'kid':222222,'cost':2,'date':'2012-02-11'},
    {'goid':1112,'kid':222225,'cost':5,'date':'2012-05-11'},
    {'goid':1111,'kid':222226,'cost':8,'date':'2012-02-11'},
]

要转换成lt2这样的结构

lt2 = [
    {
        '1111': #以goid的值为key
            {
                '2012-02-11': #date的值为key
                    [
                        {'goid':1111,'kid':222222,'cost':2,'date':'2012-02-11'},
                        {'goid':1111,'kid':222226,'cost':8,'date':'2012-02-11'}
                    ]
            }
        '1112':
            {
                '2012-05-11':
                    [
                      {'goid':1112,'kid':222225,'cost':5,'date':'2012-05-11'}  
                    ]
            }
    }
]

如果用php数组来实现很简单，但python就不知道了~~~
请帮帮忙，先谢谢了

[panghuhu250]

dict的setdefault方法在这儿很有用。

>>> lt1 = [ {'goid':1111,'kid':222222,'cost':2,'date':'2012-02-11'}, {'goid':1112,'kid':222225,'cost':5,'date':'2012-05-11'}, {'goid':1111,'kid':222226,'cost':8,'date':'2012-02-11'}, ]
>>> def transform(lt):
...     result = {}
...     for d in lt:
...         result.setdefault(d['goid'], {}).setdefault(d['date'], []).append(d)
...     return [result]
>>> transform(lt1)
9: [{1111: {'2012-02-11': [{'cost': 2,
                         'date': '2012-02-11',
                         'goid': 1111,
                         'kid': 222222},
                        {'cost': 8,
                         'date': '2012-02-11',
                         'goid': 1111,
                         'kid': 222226}]},
  1112: {'2012-05-11': [{'cost': 5,
                         'date': '2012-05-11',
                         'goid': 1112,
                         'kid': 222225}]}}]
>>>