如何从 object 的数组中获取特定键值的总和

Question

我有类似于下面的 objects 数组：

let violation = [
 {
    "timestamp": 1637658787661,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateHarshAccelerationEvent",
    "value": 71,
 },
 {
    "timestamp": 1637658789678,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateHarshDecelerationEvent",
    "value": 50,
 },
 {
    "timestamp": 1637659776571,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateIdlingEvent",
    "value": 0,
 },
 {
    "timestamp": 1637660707375,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateSpeedingEvent",
    "value": 67,
 },
 {
    "timestamp": 1637661519707,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateHarshAccelerationEvent",
    "value": 71,
 },
 {
    "timestamp": 1637661521773,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateHarshDecelerationEvent",
    "value": 50,
 },
 {
    "timestamp": 1637661548282,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateSpeedingEvent",
    "value": 62,
 },
 {
    "timestamp": 1637663230199,
    "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
    "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
    "message": "CreateSpeedingEvent",
    "value": 66,
 },
 .....
 .....  
]

所以在这里，每个 object 都会有一个 message 属性或四个值之一的键，即 CreateHarshAccelerationEvent、CreateHarshDecelerationEvent、CreateSpeedingEvent, CreateIdlingEvent.

这里我需要得到每个key的总数。即总计 CreateHarshAccelerationEvent 总计 CreateHarshDecelerationEvent 总计 CreateIdlingEvent 总计 CreateSpeedingEvent

但条件是我必须 select object 与标识符合计，而该标识符是 driver 和公司 ID 的组合，即 key = company + "/" + driver

我正在为此做以下代码

    var violations = []

    for (let violation of data){
        var key
        if ( (violation.company) && (violation.driver) ) {

            key = violation.company + "/" + violation.driver;

            let violationType = violation.message; 

            violations[key].company = violation.company;
            violations[key].driver = violation.driver;
            
        }

    }

    console.log(violations);

我需要结果为

[{
   "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7",
   "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5",
   "CreateHarshAccelerationEvent": "total number of values CreateHarshAccelerationEvent from Array of objects basis on the basis of that custom key i.e. company/driver value",
   "CreateHarshDecelerationEvent": "total number of values CreateHarshDecelerationEvent from Array of objects basis on the basis of that custom key i.e. company/driver value",
   "CreateIdlingEvent": "total number of values CreateIdlingEvent from Array of objects basis on the basis of that custom key i.e. company/driver value",
   "CreateSpeedingEvent": "total number of values CreateSpeedingEvent from Array of objects basis on the basis of that custom key i.e. company/driver value", 
}]

Answer 1

您的方法有问题。您不能将字符串用作数组中的键，因此您需要将其更改为对象 const violations = {}

也在你做之前 violations[key].speeding++ 确保初始化为 0，因为你试图在此处增加 undefined 值

Answer 2

您可以使用 array#reduce 总结相同 driver 和 company 的不同事件。

let violation = [ { "timestamp": 1637658787661, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateHarshAccelerationEvent", "value": 71, }, { "timestamp": 1637658789678, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateHarshDecelerationEvent", "value": 50, }, { "timestamp": 1637659776571, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateIdlingEvent", "value": 0, }, { "timestamp": 1637660707375, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateSpeedingEvent", "value": 67, }, { "timestamp": 1637661519707, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateHarshAccelerationEvent", "value": 71, }, { "timestamp": 1637661521773, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5","message": "CreateHarshDecelerationEvent", "value": 50, }, { "timestamp": 1637661548282, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateSpeedingEvent", "value": 62, }, { "timestamp":1637663230199, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateSpeedingEvent", "value": 66, }],
     result = Object.values(violation.reduce((r, o) => {
      const key = o.driver + '_' + o.company;
      r[key] ??= {driver: o.driver, company: o.company};
      r[key][o.message] = (r[key][o.message] ?? 0) + o.value;
      return r;
     },{}));
console.log(result);

Answer 3

Array.reduce 会帮助你。

let violation = [ { "timestamp": 1637658787661, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateHarshAccelerationEvent", "value": 71, }, { "timestamp": 1637658789678, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateHarshDecelerationEvent", "value": 50, }, { "timestamp": 1637659776571, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateIdlingEvent", "value": 0, }, { "timestamp": 1637660707375, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateSpeedingEvent", "value": 67, }, { "timestamp": 1637661519707, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateHarshAccelerationEvent", "value": 71, }, { "timestamp": 1637661521773, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5","message": "CreateHarshDecelerationEvent", "value": 50, }, { "timestamp": 1637661548282, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateSpeedingEvent", "value": 62, }, { "timestamp":1637663230199, "driver": "7f5fda5d-86a8-471e-ae32-fcc39deb8fc7", "company": "9d8616dd-4689-4689-8812-a2345ccdcfc5", "message": "CreateSpeedingEvent", "value": 66, }];
const result = violation.reduce((acc, curr) => {
  const node = acc.find(item => item.driver === curr.driver && item.company === curr.company);
  if (node) node[curr.message] ? node[curr.message] += curr.value : node[curr.message] = curr.value
  else
    acc.push({
      driver: curr.driver,
      company: curr.company,
      [curr.message]: curr.value
    });
  return acc;
}, []);
console.log(result);

如何从 object 的数组中获取特定键值的总和

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