Mongo Group 和两个字段的总和 [英] Mongo Group and sum with two fields

问题描述

我有如下文件:

{
   "from":"[e-mail]",
   "to" :"[e-mail]",
   "email": "Hi hello"
}

我们如何计算from and to"或to and from"的总和计数?喜欢两个人​​之间的交流吗?

How can we calculate count of sum "from and to" or "to and from"? Like communication counts between two people?

我能够计算一种方式的总和.我想双向求和.

I am able to calculate one way sum. I want to have sum both ways.

db.test.aggregate([
      { $group: {
         "_id":{ "from": "$from", "to":"$to"},
           "count":{$sum:1} 
         }
      },
      { 
        "$sort" :{"count":-1}
      }
])

推荐答案

由于需要计算在 2个地址之间交换的电子邮件数量，所以投影一个统一的在 字段如下:

Since you need to calculate number of emails exchanged between 2 addresses, it would be fair to project a unified between field as following:

db.a.aggregate([
    { $match: {
        to: { $exists: true },
        from: { $exists: true },
        email: { $exists: true }
    }}, 
    { $project: {
        between: { $cond: { 
            if: { $lte: [ { $strcasecmp: [ "$to", "$from" ] }, 0 ] }, 
            then: [ { $toLower: "$to" }, { $toLower: "$from" } ], 
            else: [ { $toLower: "$from" }, { $toLower: "$to" } ] }
        } 
    }},
    { $group: {
         "_id": "$between",
         "count": { $sum: 1 } 
    }},
    { $sort :{ count: -1 } }
])

这个例子中的统一逻辑应该很清楚:它是一个按字母顺序排列的两封电子邮件的数组.如果您信任您的数据，则 $match 和 $toLower 部分是可选的.

Unification logic should be quite clear from the example: it is an alphabetically sorted array of both emails. The $match and $toLower parts are optional if you trust your data.

示例中使用的运算符的文档:

Documentation for operators used in the example:

• $match
• $exists
• $project
• $cond
• $lte
• $strcasecmp
• $toLower
• $group
• $sum
• $sort

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