Python中合并同键字典的对象列表：代码问题排查

需求说明 #

我有一个由多个字典组成的列表，每个字典的键为活动名称，值是单个活动对象的列表，原始数据如下：

{'Kitchen_Activity': [date= 2009-10-16, start time= 08:45:38, end time= 08:58:52, duration= 0 days 00:13:14 ]}
{'Chores': [date= 2009-10-16, start time= 08:59:02, end time= 09:14:47, duration= 0 days 00:15:45 ]}
{'Kitchen_Activity': [date= 2009-10-16, start time= 09:14:40, end time= 09:14:54, duration= 0 days 00:00:14 ]}
{'Chores': [date= 2009-10-16, start time= 09:30:40, end time= 09:58:54, duration= 0 days 00:28:14 ]}
{'Kitchen_Activity': [date= 2009-10-16, start time= 10:14:40, end time= 10:14:54, duration= 0 days 00:00:14 ]}
{'Shower': [date= 2009-10-16, start time= 11:14:40, end time= 11:40:40, duration= 0 days 00:26:00 ]}

期望将相同活动名称对应的对象合并到同一个列表中，得到如下结果：

{'Kitchen_Activity': [date= 2009-10-16, start time= 08:45:38, end time= 08:58:52, duration= 0 days 00:13:14 ], [date= 2009-10-16, start time= 09:14:40, end time= 09:14:54, duration= 0 days 00:00:14 ], [date= 2009-10-16, start time= 10:14:40, end time= 10:14:54, duration= 0 days 00:00:14 ]}
{'Chores': [date= 2009-10-16, start time= 08:59:02, end time= 09:14:47, duration= 0 days 00:15:45 ], [date= 2009-10-16, start time= 09:30:40, end time= 09:58:54, duration= 0 days 00:28:14 ]}
{'Shower': [date= 2009-10-16, start time= 11:14:40, end time= 11:40:40, duration= 0 days 00:26:00 ]}

现有代码的问题 #

我编写的generateActivity函数无法得到期望结果，代码如下：

def generateActivity(self, date, name, ts, te, dur):
        activities = {}
        activity = Activity().generateInstance(date, name, ts, te, dur)

        if activity.name not in activities.keys():
            activities[activity.name] = []
            activities[activity.name].append(activity)
        else:
            for key, item in activities.items():
                if key == activity.name:
                    item.append(activity)
        return activities

问题出在两个地方：

1. 每次调用都会重置字典：函数内部每次都新建空字典activities = {}，导致每次调用只能返回包含当前活动的字典，之前添加的活动数据完全丢失，根本无法实现累积合并。
2. 多余的遍历操作：else分支里遍历整个字典的操作完全没必要，既然已经确认activity.name在字典的键中，直接通过键访问对应的列表并追加元素即可，无需遍历。

修正后的代码 #

把activities改为类的实例变量，确保每次调用都能在同一个字典中累积数据，同时简化逻辑：

def generateActivity(self, date, name, ts, te, dur):
    # 初始化实例变量，确保首次调用时创建空字典
    if not hasattr(self, 'activities'):
        self.activities = {}
    activity = Activity().generateInstance(date, name, ts, te, dur)
    
    # 直接通过活动名称操作对应列表，无需多余判断和遍历
    if activity.name not in self.activities:
        self.activities[activity.name] = []
    self.activities[activity.name].append(activity)
    return self.activities

内容的提问来源于stack exchange，提问作者accipigna