如何筛选具有给定键的匹配值的词典列表

Question

有了像这样的界面a = copyf(dictlist, key, valuelist).

>>> dictlist = [{'first': 'James',
                 'last': 'Joule'},
                {'first': 'James',
                 'last': 'Watt'},
                {'first': 'Christian',
                 'last': 'Doppler'}]
>>> valuelist = ['James', 'John']
>>> x = copyf(dictlist, 'first', valuelist)
>>> print(x)
[{'first': 'James',
  'last': 'Joule'},
 {'first': 'James',
  'last': 'Watt'}]

这dictlist实际上是一个csv.DictReader例子.

Answer 1

更新:考虑到OP的重新编写问题:

def copyf(dictlist, key, valuelist):
      return [dictio for dictio in dictlist if dictio[key] in valuelist]

Answer 2

可能不是最好的解决方案,但在这里我们走了:

>>> def copyf(data, key, allowed):
...     return filter(lambda x: key in x and x[key] in allowed, data)
... 
>>> dictlist = [{'first': 'James', 'last': 'Joule'}, {'first': 'James','last': 'Watt'},{'first': 'Christian','last': 'Doppler'}]
>>> copyf(dictlist, 'first', ('Christian',))
[{'last': 'Doppler', 'first': 'Christian'}]
>>> copyf(dictlist, 'last', ('Christian',))
[]
>>> copyf(dictlist, 'first', ('James',))
[{'last': 'Joule', 'first': 'James'}, {'last': 'Watt', 'first': 'James'}]
>>>