Javascript 使用lodash的地图数据

我有这样的数据：

const data = {
   "result":[
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:00.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:01.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:58.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":3
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:59.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:26:00.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:26:01.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      }
   ]
};

{
   "2020-10-23T07:25:00.000Z":{
      "2": { avgSpeed: 0, avgVehicleLength: 0, avgGap: 0, avgOccupancy: 0, numVehicles: 3},
      "3": { avgSpeed: 0, avgVehicleLength: 0, avgGap: 0, avgOccupancy: 0, numVehicles: 1}
   },
   "2020-10-23T07:26:00.000Z":{
      "2": { avgSpeed: 0, avgVehicleLength: 0, avgGap: 0, avgOccupancy: 0, numVehicles: 1},
   }
}

我想按日期、车辆类型和此值之和对数据进行排序。所以我从洛达斯得到了

const groupedItems = _(data.result)
  .groupBy(item => new Date(new Date(item.timestamp).setSeconds(0,0)).toISOString())
  .mapValues((array, sort) => _.groupBy(array, item => item.vehicleType))
  .value();

我得到：

{
   "2020-10-23T07:25:00.000Z":{
      "2":[
         {
            "intersectionId":77,
            "deviceNumber":300,
            "timestamp":"2020-10-23T07:25:00.000+0000",
            "outstationId":null,
            "occupancy":0,
            "gap":0,
            "journeyTime":null,
            "speed":0,
            "vehicleLength":0,
            "vehicleType":2
         },
         {
            "intersectionId":77,
            "deviceNumber":300,
            "timestamp":"2020-10-23T07:25:01.000+0000",
            "outstationId":null,
            "occupancy":0,
            "gap":0,
            "journeyTime":null,
            "speed":0,
            "vehicleLength":0,
            "vehicleType":2
         },
         {
            "intersectionId":77,
            "deviceNumber":300,
            "timestamp":"2020-10-23T07:25:59.000+0000",
            "outstationId":null,
            "occupancy":0,
            "gap":0,
            "journeyTime":null,
            "speed":0,
            "vehicleLength":0,
            "vehicleType":2
         }
      ],
      "3":[
         {
            "intersectionId":77,
            "deviceNumber":300,
            "timestamp":"2020-10-23T07:25:58.000+0000",
            "outstationId":null,
            "occupancy":0,
            "gap":0,
            "journeyTime":null,
            "speed":0,
            "vehicleLength":0,
            "vehicleType":3
         }
      ]
   },
   "2020-10-23T07:26:00.000Z":{
      "2":[
         {
            "intersectionId":77,
            "deviceNumber":300,
            "timestamp":"2020-10-23T07:26:00.000+0000",
            "outstationId":null,
            "occupancy":0,
            "gap":0,
            "journeyTime":null,
            "speed":0,
            "vehicleLength":0,
            "vehicleType":2
         },
         {
            "intersectionId":77,
            "deviceNumber":300,
            "timestamp":"2020-10-23T07:26:01.000+0000",
            "outstationId":null,
            "occupancy":0,
            "gap":0,
            "journeyTime":null,
            "speed":0,
            "vehicleLength":0,
            "vehicleType":2
         }
      ]
   }
}

这很好，但我想得到每种车辆类型的变量总和（速度、车辆长度、占用率），如下所示：

const data = {
   "result":[
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:00.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:01.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:58.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":3
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:25:59.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:26:00.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      },
      {
         "intersectionId":77,
         "deviceNumber":300,
         "timestamp":"2020-10-23T07:26:01.000+0000",
         "outstationId":null,
         "occupancy":0,
         "gap":0,
         "journeyTime":null,
         "speed":0,
         "vehicleLength":0,
         "vehicleType":2
      }
   ]
};

{
   "2020-10-23T07:25:00.000Z":{
      "2": { avgSpeed: 0, avgVehicleLength: 0, avgGap: 0, avgOccupancy: 0, numVehicles: 3},
      "3": { avgSpeed: 0, avgVehicleLength: 0, avgGap: 0, avgOccupancy: 0, numVehicles: 1}
   },
   "2020-10-23T07:26:00.000Z":{
      "2": { avgSpeed: 0, avgVehicleLength: 0, avgGap: 0, avgOccupancy: 0, numVehicles: 1},
   }
}

---

您试图做的是将多个值减少为一个值

谢天谢地，这个用例非常常见，这意味着JavaScript已经有了执行此类操作的方法（lodash也有一组方法，具体取决于您试图实现的目标）

根据您的问题陈述，我们需要总结对象列表的特定属性，例如：

const totalSpeed = _.sumBy(items, 'speed')

它将“拾取”每个项目的

speed

属性并将它们相加

现在我们有了基本情况的解决方案，我们可以将项目列表缩减为包含汇总属性的对象：

constgroupeditems=\uU4（data.result）
.groupBy（item=>newdate（newdate（item.timestamp）.setSeconds（0,0））.toISOString（））
.mapValues（数组=>(数组）
.groupBy（项目=>item.vehicleType）
.mapValues（项目=>({
平均速度：uu.sumBy（项目“速度”），
avgGap:uu.sumBy（项目“差距”），
avgOccupancy:uu.sumBy（项目“占用率”），
平均车辆长度：uu.sumBy（项目“车辆长度”），
车辆数量：尺寸（项目）
}))
.value（）
)
.value（）

如果你想增加你的问题被当作垃圾邮件处理的机会，那么在问题的末尾加上毫无意义的字符串

…

，肯定是一个很好的方法。如果你不认真对待你的问题，我们为什么要这样做？