【问题标题】：Aggregate certain values in array of dictionary based on key/value criteria根据键/值标准聚合字典数组中的某些值
【发布时间】：2020-03-30 08:59:57
【问题描述】：

我有以下论坛帖子的 JSON。创建每个论坛汇总的正面/负面评级的结果 JSON 的 pythonic 方式是什么？

输入Json：

{"Posting_Stats":{
      "Posts":[
         {
            "Date":"2020-03-29 12:41:00",
            "Forum":"panorama",
            "Positive":2,
            "Negative":0
         },
         {
            "Date":"2020-03-29 12:37:00",
            "Forum":"web",
            "Positive":6,
            "Negative":0
         },
         {
            "Date":"2020-03-29 12:37:00",
            "Forum":"web",
            "Positive":2,
            "Negative":2
         },...]}

输出应该是：

{"Forum_Stats" : [{"Forum" : "panorama",
                  "Positive":2,
                  "Negative":0},
                 {"Forum" : "web",
                  "Positive":8,
                  "Negative":2},...]
}

]

【问题讨论】：

标签： python arrays json list dictionary

【解决方案1】：

想不出别的办法：

posts = inputData['Posting_Stats']['Posts']
postAggregator = {}
for post in posts:
    try:
        postAggregator[post['Forum']]['Positive'] += post.get('Positive',0)
        postAggregator[post['Forum']]['Negative'] += post.get('Negative',0)
    except KeyError:
        postAggregator.update({post['Forum']:{"Positive":post.get('Positive',0), "Negative":post.get('Negative',0)}})

outputData = {"Forum_Stats": []}
for key, value in postAggregator.items():
    outputData['Forum_Stats'].append({"Forum":key , "Positive":value['Positive'],"Negative":value['Negative']})

print(outputData)

输出：

{'Forum_Stats': [{'Forum': 'panorama', 'Positive': 2, 'Negative': 0}, {'Forum': 'web', 'Positive': 8, 'Negative': 2}]}

【讨论】：

【解决方案2】：

这可能是一种解决方法：

#taking the input in a dictionary
d = {"Posting_Stats":{
      "Posts":[
         {
            "Date":"2020-03-29 12:41:00",
            "Forum":"panorama",
            "Positive":2,
            "Negative":0
         },
         {
            "Date":"2020-03-29 12:37:00",
            "Forum":"web",
            "Positive":6,
            "Negative":0
         },
         {
            "Date":"2020-03-29 12:37:00",
            "Forum":"web",
            "Positive":2,
            "Negative":2
         }]}}

#iterating over the values to get their some on the basis of forum as key
temp = {}
for i in d.get('Posting_Stats').get('Posts'):
    if temp.get(i.get('Forum')) == None:
        temp[i.get('Forum')] = {}
        temp[i.get('Forum')]['Positive'] = 0
        temp[i.get('Forum')]['Negative'] = 0
    temp[i.get('Forum')]['Positive']+=i.get('Positive')
    temp[i.get('Forum')]['Negative']+=i.get('Negative')

最后将输出转换成需要的格式

output = [{'Forum': i , **temp[i] } for i in temp]
print(output)

#[{'Forum': 'panorama', 'Positive': 2, 'Negative': 0},
#{'Forum': 'web', 'Positive': 8, 'Negative': 2}]

【讨论】：