python - 访问嵌套字典列表中的值

Question

我的字典是这样的:

docScores = {0:[{u'word':2.3},{u'the':8.7},{u'if':4.1},{u'Car':1.7}],
             1:[{u'friend':1.2},{u'a':5.2},{u'you':3.8},{u'person':0.8}],
             ...
             29:[{u'yard':1.5},{u'gardening':2.8},{u'paint':3.7},{u'brush':1.6}]
            }

我想对每个列表的每个内部字典的值求和并将其存储在一个新字典中，新字典的键值为 {0:2.3+8.7+4.1+1.7, 1:1.2+ 5.2+3.8+0.8, ...等即

for x in docScores[0]: #{0:
    for x in docScores[0][0].values(): #{,2.3}.
        sum = sum+x #where sum = 0 before loop
        docSum[0] = sum
    repeat this loop for every document

我尝试过的任何变体都会给我意想不到的输出。谁能给我正确的语法？

Answer 1

这个字典理解有效:

docScores = {0:[{u'word':2.3},{u'the':8.7},{u'if':4.1},{u'Car':1.7}],
             1:[{u'friend':1.2},{u'a':5.2},{u'you':3.8},{u'person':0.8}],
             29:[{u'yard':1.5},{u'gardening':2.8},{u'paint':3.7},{u'brush':1.6}]
            }

sum_d={k:sum(d.values()[0] for d in v) for k,v in docScores.items()}

print sum_d

打印:

{0: 16.8, 1: 11.0, 29: 9.6}

但是，更改数据结构可能更容易。你可以有一个 dict of dicts:

>>> NdocScores = {0:{u'word':2.3,u'the':8.7,u'if':4.1,u'Car':1.7},
...              1:{u'friend':1.2,u'a':5.2,u'you':3.8,u'person':0.8},
...              29:{u'yard':1.5,u'gardening':2.8,u'paint':3.7,u'brush':1.6}
...             }   

允许直接访问每个文档数据:

>>> NdocScores[0]
{u'Car': 1.7, u'the': 8.7, u'word': 2.3, u'if': 4.1}
>>> NdocScores[0][u'Car']
1.7
>>> sum(NdocScores[1].values())
11.0

>>> NdocScores[29]
{u'gardening': 2.8, u'yard': 1.5, u'brush': 1.6, u'paint': 3.7}

或者，只是有一个字典列表，列表中的位置对应于文档索引:

>>> lofdicts=[v for k,v in NdocScores.items()]
>>> lofdicts
[{u'Car': 1.7, u'the': 8.7, u'word': 2.3, u'if': 4.1}, {u'a': 5.2, u'person': 0.8, u'you': 3.8, u'friend': 1.2}, {u'gardening': 2.8, u'yard': 1.5, u'brush': 1.6, u'paint': 3.7}]
>>> lofdicts[0]
{u'Car': 1.7, u'the': 8.7, u'word': 2.3, u'if': 4.1}
>>> sum(lofdicts[1].values())
11.0