Python - 从字典列表中删除重复键

Question

我有一个 Python 字典列表:

[{u'value': u'firstname', u'key': u'Coach'}, 
 {u'value': u'lastname', u'key': u'Coach'}, 
 {u'value': u'age', u'key': u'Coach'}, 
 {u'value': u'firstname', u'key': u'Player'}, 
 {u'value': u'league', u'key': u'Player'}]

如何从字典列表中删除重复的 key 并将它们的值合并到列表中，如下所示:

l = [('Coach', ['firstname', 'lastname', 'age']), 
     ('Player', ['firstname', 'league'])]

遍历列表项

for k, v in l:
    print k, v

Answer 1

你可以使用 defaultdict与 list作为值类型以收集值:

In [5]: from collections import defaultdict

In [6]: data = [{u'value': u'firstname', u'key': u'Coach'}, 
 {u'value': u'lastname', u'key': u'Coach'}, 
 {u'value': u'age', u'key': u'Coach'}, 
 {u'value': u'firstname', u'key': u'Player'}, 
 {u'value': u'league', u'key': u'Player'}]

In [7]: l = defaultdict(list)

In [8]: for row in data:
   ...:     l[row['key']].append(row['value'])
   ...:     

In [9]: l
Out[9]: 
defaultdict(list,
            {'Coach': ['firstname', 'lastname', 'age'],
             'Player': ['firstname', 'league']})

然后您可以使用 items 轻松地将字典转换为元组列表。方法:

In [10]: list(l.items())
Out[10]: 
[('Coach', ['firstname', 'lastname', 'age']),
 ('Player', ['firstname', 'league'])]