Python:按部分键对多级字典进行排序

Question

我有这样的字典:

{
   '28.10.11/D/text1/' : {key:value1},
   '27.01.11/D/text2/' : {key:value2},
   '07.11.12/D/text3/' : {key:value3}
}

部分 key 基于日期，以“%d.%m.%Y”格式设置。需要按日期对所有字典键进行排序。值必须以相同的格式保存。示例:

{
   '27.01.11/D/text2/' : {key:value2},   
   '28.10.11/D/text1/' : {key:value1},
   '07.11.12/D/text3/' : {key:value3}
}

Answer 1

您无法对标准词典进行排序，但可以对项目进行排序和显示。

from datetime import datetime

D = {'28.10.11/D/text1/' : {'key':'value1'},
     '27.01.11/D/text2/' : {'key':'value2'},
     '07.11.12/D/text3/' : {'key':'value3'}}

for k in sorted(D,key=lambda k: datetime.strptime(k[:8],"%d.%m.%y")):
    print(k,D[k])

输出:

27.01.11/D/text2/ {'key': 'value2'}
28.10.11/D/text1/ {'key': 'value1'}
07.11.12/D/text3/ {'key': 'value3'}

如果你想使用列表:

from datetime import datetime
from pprint import pprint

L = [('28.10.11/D/text1/' , {'key':'value1'}),
     ('27.01.11/D/text2/' , {'key':'value2'}),
     ('07.11.12/D/text3/' , {'key':'value3'})]

L.sort(key=lambda k: datetime.strptime(k[0][:8],"%d.%m.%y"))
pprint(L)

输出:

[('27.01.11/D/text2/', {'key': 'value2'}),
 ('28.10.11/D/text1/', {'key': 'value1'}),
 ('07.11.12/D/text3/', {'key': 'value3'})]

最后，如果您仍然想要字典行为，OrderedDict 会记住插入的顺序键，所以:

from collections import OrderedDict
from datetime import datetime
from pprint import pprint

D = {'28.10.11/D/text1/' : {'key':'value1'},
     '27.01.11/D/text2/' : {'key':'value2'},
     '07.11.12/D/text3/' : {'key':'value3'}}

OD = OrderedDict(sorted(D.items(),
                 key=lambda k: datetime.strptime(k[0][:8],"%d.%m.%y"))
pprint(OD)

输出:

{'27.01.11/D/text2/': {'key': 'value2'},
 '28.10.11/D/text1/': {'key': 'value1'},
 '07.11.12/D/text3/': {'key': 'value3'}}