python - 更新字典列表中的值

Question

我有一个类似这样的字典列表:

users=[{"name": "David", "team": "reds", "score1": 100, "score2": 20,},
       {"name": "David", "team": "reds", "score1": 20, "score2": 60,},
       {"name": "David", "team": "blues", "score1": 10, "score2": 70,}]

并且真的很想得到一个新的处理过的字典列表，比如

summary=[{"team": "reds", "total1": 120, "total2": 80,},
         {"team": "blues", "total1": 120, "total2": 80,}]

最好只循环一次原始数据。我可以创建一个字典，其中包含每个用户键的总值

summary = dict()
for user in users:
   if not user['team'] in summary:
      summary[user['team']]=float(user['score1'])
   else:
      summary[user['team']]+=float(user['score1'])

给予

summary = {'reds': 120,'blues': 10}

但是我正在努力生成字典列表，我能得到的最接近的方法是在团队的第一个实例中创建一个字典，然后尝试在后续出现时附加到它的值...

summary = []
for user in users:
   if any(d['team'] == user['team'] for d in summary):
      # append to values in the relevant dictionary
      # ??
   else:
      # Add dictionary to list with some initial values
      d ={'team':user['team'],'total1':user['score1'],'total2':user['score2']}
      summary.append(dict(d))

...它变得一团糟...我是不是以完全错误的方式处理这件事？您可以更改列表中字典中的值吗？

谢谢

Answer 1

我认为这是使用 pandas 的好案例python 库:

>>> import pandas as pd
>>> dfUsers = pd.DataFrame(users)
>>> dfUsers

    name  score1  score2   team
0  David     100      20   reds
1  David      20      60   reds
2  David      10      70  blues

>>> dfUsers.groupby('team').sum()

       score1  score2
team                 
blues      10      70
reds      120      80

如果你真的想把它放入dict:

>>> dfRes = dfUsers.groupby('team').sum()
>>> dfRes.columns = ['total1', 'total2']  # if you want to rename columns
>>> dfRes.reset_index().to_dict(orient='records')

[{'team': 'blues', 'total1': 10, 'total2': 70},
 {'team': 'reds', 'total1': 120, 'total2': 80}]

另一种方法是使用 itertools.groupby :

>>> from itertools import groupby
>>> from operator import itemgetter
>>> users.sort(key=itemgetter('team'))
>>>
>>> res = [{'team': t[0], 'res': list(t[1])} for t in groupby(users, key=itemgetter('team'))]
>>> res = [{'team':t[0], 'total1': sum(x['score1'] for x in t[1]), 'total2': sum(x['score2'] for x in t[1])} for t in res]
>>> res

[{'team': 'blues', 'total1': 10, 'total2': 70},
 {'team': 'reds', 'total1': 120, 'total2': 80}]

或者，如果你真的想要简单的 python:

>>> res = dict()
>>> for x in users:
       if x['team'] not in res:
           res[x['team']] = [x['score1'], x['score2']]
       else:
           res[x['team']][0] += x['score1']
           res[x['team']][1] += x['score2']
>>> res = [{'team': k, 'total1': v[0], 'total2': v[1]} for k, v in res.iteritems()}]
>>> res

[{'team': 'reds', 'total1': 120, 'total2': 80},
 {'team': 'blues', 'total1': 10, 'total2': 70}]