查询使用每个平均值的计数查找 mongodb 中存储的平均值的平均值

Question

我们有这样的数据

{
    "_id" : ObjectId("64326493749326499446"),
    "dId" : "d_155",
    "pId" : "5f4cb595cff47e0001b20882",
    "sId" : "825",
    "paramName" : "Utility_Air_Flow",
 "avg" : 488270.454545455,
            "count" : NumberLong(220),
    "date" : ISODate("2020-09-03T18:30:00.000Z"),
    "dataPerHour" : {
        "19" : {
            "min" : 8399.0,
            "max" : 995990.0,
            "avg" : 488270.454545455,
            "count" : NumberLong(220),
            "values" : [ 
                {
                    "paramValue" : "90235",
                    "time" : ISODate("2020-09-04T13:37:07.000Z")
                }, 
                {
                    "paramValue" : "272297",
                    "time" : ISODate("2020-09-04T13:37:14.000Z")
                }
            ]
        },
        "20" : {
            "min" : 8399.0,
            "max" : 995990.0,
            "avg" : 488270.454545455,
            "count" : NumberLong(220),
            "values" : [ 
                {
                    "paramValue" : "90235",
                    "time" : ISODate("2020-09-04T13:37:07.000Z")
                }, 
                {
                    "paramValue" : "272297",
                    "time" : ISODate("2020-09-04T13:37:14.000Z")
                }
            ]
        }
    },
    "_class" : "org.nec.iotplatform.entities.RawData"
}

我们需要找到 dataPerHour 中已存储的所有平均值的平均值。

我们需要根据公式求平均值：

(average1count1)+(avarege2count2)+ (average3*count3)/(count1+count2+count3)

Answer 1

您可以使用以下查询：

db.collection.aggregate([
  {
    $project: {
      dataPerHour: {
        $objectToArray: "$dataPerHour"
      }
    }
  },
  {
    $project: {
      "average": {
        "$divide": [
          {
            $reduce: {
              input: "$dataPerHour",
              initialValue: 0,
              in: {
                "$add": [
                  "$$value",
                  {
                    "$multiply": [
                      "$$this.v.count",
                      "$$this.v.avg"
                    ]
                  }
                ]
              }
            }
          },
          {
            $reduce: {
              input: "$dataPerHour",
              initialValue: 0,
              in: {
                "$add": [
                  "$$value",
                  "$$this.v.count"
                ]
              }
            }
          }
        ]
      }
    }
  }
])

MongoDB Playground

查询使用每个平均值的计数查找 mongodb 中存储的平均值的平均值

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