Python 以一个字段为基础计算另一个字段

我是MongoDB的初学者。我收集了几百万份文件。文件示例：

我想找到每个唯一用户id的用户\追随者\数量、用户\朋友\数量和用户\提及总数

data.aggregate([
       {"$group" : {"_id":{"followers_count":"$user_followers_count", "friends_count": "$user_friends_count"}, "followers_count":{"$sum:1"}}} ])

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我正在尝试，但没有得到结果。有人能帮忙吗？

这可以为您提供预期的输出：

db.data.aggregate([ {$project:{usr_mentions:{ $cond: { if: { $isArray: "$user_mentions" }, then: { $size: "$user_mentions" }, else: 0} } , user_id:1,user_followers_count:1,user_friends_count:1   }}   ,  {$group:{ _id:"$user_id" , user_followers_total_count:{$sum:"$user_followers_count"} , user_friends_total_count:{$sum:"$user_friends_count"} , usr_mentions_total_count:{ $sum:"$usr_mentions" }     }}    ])

输出如下所示：

{ "_id" : userX, "user_followers_total_count" : 50, "user_friends_total_count" : 20, "usr_mentions_total_count" : 2 }
{ "_id" : userY, "user_followers_total_count" : 150, "user_friends_total_count" : 60, "usr_mentions_total_count" : 6 }

请记住，如果在项目阶段没有提及次数，查询将只需要分组阶段，而且会更快

mongod/mongos 4.4测试：

mongos> db.data.find()
{ "_id" : ObjectId("5ff4f4e6df14d22947f36205"), "tweet_id" : 1, 
"user_id" : 2, "user_followers_count" : 50, "user_friends_count" : 20, 
"user_tweets_count" : 30, "user_mentions" : [ 0, 1 ] }
{ "_id" : ObjectId("5ff4f4f4df14d22947f36206"), "tweet_id" : 3, 
"user_id" : 4, "user_followers_count" : 50, "user_friends_count" : 20, 
"user_tweets_count" : 30, "user_mentions" : [ 0, 1 ] }
{ "_id" : ObjectId("5ff4f58bdf14d22947f36207"), "tweet_id" : 3, 
"user_id" : 4, "user_followers_count" : 50, "user_friends_count" : 20, 
"user_tweets_count" : 30, "user_mentions" : [ 0, 1 ] }
{ "_id" : ObjectId("5ff4f590df14d22947f36208"), "tweet_id" : 3, 
"user_id" : 4, "user_followers_count" : 50, "user_friends_count" : 20, 
"user_tweets_count" : 30, "user_mentions" : [ 0, 1 ] }

mongos> db.data.aggregate([ {$project:{usr_mentions:{ $cond: { if: { 
$isArray: "$user_mentions" }, then: { $size: "$user_mentions" }, else: 
 0} } , user_id:1,user_followers_count:1,user_friends_count:1   }}   ,  
{$group:{ _id:"$user_id" , user_followers_total_count: 
{$sum:"$user_followers_count"} , user_friends_total_count: 
{$sum:"$user_friends_count"} , usr_mentions_total_count:{ 
$sum:"$usr_mentions" }     }}    ])

{ "_id" : 4, "user_followers_total_count" : 150, 
"user_friends_total_count" : 60, "usr_mentions_total_count" : 6 }
{ "_id" : 2, "user_followers_total_count" : 50, 
"user_friends_total_count" : 20, "usr_mentions_total_count" : 2 }
mongos> 

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谢谢你的回复。这给了我一个无效的语法错误。（用版本4.4测试）抱歉。我在Pymongo语法中犯了一些错误。成功了。谢谢！