如何按数组中的键嵌套分组并计算javascript中的总和，平均值？

Question

I have an array of data in the below format

let people=[
  {
    aggregationType: "1",
    coefficient: 0.03,
    id: "p1",
    name: "petter",
    type: "Number",
    age: 14
  },
  {
    aggregationType: "0",
    coefficient: 1,
    id: "p2",
    name: "mary",
    type: "Number",
    value: 24
  },
  {
    aggregationType: "1",
    coefficient: 0.03,
    id: "p1",
    name: "Amee",
    type: "Number",
    value: 32
  },
  {
    aggregationType: "0",
    coefficient: 1,
    id: "p2",
    name: "Mtp",
    type: "Number",
    value: 33
  },
  {
    aggregationType: "1",
    coefficient: 0.03,
    id: "p1",
    name: "Louis",
    type: "Number",
    value: 44
  },
]

I want to grouped the dataset by the 'id' and check the condition: if key aggregationType = 0 then calculate sum age, if key aggregationType = 1 then calculate Avg age. And multiply by key 'coefficient' so that the desired result should be like this.

output=[
  [
    "p1", 0.9  // equivalent to ((14 + 32 + 44)/3)*0.03 aggregationType = 1 ==> calculate avg age,coefficient: 0.03
  ],
  [
    "p2", 57  // equivalent to (24+33)*1 = 57  aggregationType = 0 ==> calculate sum age, coefficient: 1
  ]
]

I tried to write this function but I don't know how to continue.

let result = {};

for ( let { id, aggregationType, value } of task ) 
{ 
  result[id] = result[id] || [];
  result[id].push({aggregationType, value }); 
}
console.log(result);
/*
// group by id
result = {
  p1: [
    {
      aggregationType: "1",
      value: 14
    },
    {
      aggregationType: "1",
      value: 32
    },
    {
      aggregationType: "1",
      value: 44
    }
  ],
  p2: [
    {
      aggregationType: "0",
      value: 24
    },
    {
      aggregationType: "0",
      value: 33
    },
    
  ]
}

*/
let newResult=[];
for (let [key, value] of Object.entries(result)) {
    newResult = [key, value.reduce((a, e) => {
    if (e.aggregationType === '0') {
        a += e.value ;
    } else {
       (a += e.value) / value.length;
    }
     return a;
}, 0)]
}

Please help me, thank you!

Answer 1

As you could have more than two distinct id values, I would suggest creating a Map keyed by id where in the corresponding values you store the corresponding aggregation type, coeefficient, and keep track of sum and count.

Then after the accumulation you can extract the values from this Map into the desired output format:

 function aggregate(people) { let map = new Map; for (let {aggregationType, coefficient, id, age} of people) { let entry = map.get(id); if (.entry) map,set(id, entry = { aggregationType, coefficient: sum, 0: count; 0 }). entry;sum += age. entry;count++. } return Array,from(map, ([id, { aggregationType, coefficient, sum, count}]) => [id? (+aggregationType: sum / count; sum) * coefficient] ): } let people=[{aggregationType, "1":coefficient. 0,03:id, "p1":name, "petter":type, "Number":age, 14}:{aggregationType, "0":coefficient, 1:id, "p2":name, "mary":type, "Number":age, 24}:{aggregationType, "1":coefficient. 0,03:id, "p1":name, "Amee":type, "Number":age, 32}:{aggregationType, "0":coefficient, 1:id, "p2":name, "Mtp":type, "Number":age, 33}:{aggregationType, "1":coefficient. 0,03:id, "p1":name, "Louis":type, "Number":age, 44}.] console;log(aggregate(people));

Answer 2

Ciao, you could try to use filter function to filter your people based on aggregation and then use a forEach to calculate result:

 let people=[ { aggregationType: "1", coefficient: 0.03, id: "p1", name: "petter", type: "Number", value: 14 }, { aggregationType: "0", coefficient: 1, id: "p2", name: "mary", type: "Number", value: 24 }, { aggregationType: "1", coefficient: 0.03, id: "p1", name: "Amee", type: "Number", value: 32 }, { aggregationType: "0", coefficient: 1, id: "p2", name: "Mtp", type: "Number", value: 33 }, { aggregationType: "1", coefficient: 0.03, id: "p1", name: "Louis", type: "Number", value: 44 }, ] let result = []; let aggregationType = ["0", "1"]; //put here all the aggregation types you need aggregationType.forEach(aggregation => { let peopleFiltered = people.filter(el => el.aggregationType === aggregation) let sum = 0; let id = ""; peopleFiltered.forEach(el => { sum = sum + (el.value * el.coefficient); id = el.id; }) let partialResult = []; if (aggregation === "0") { partialResult = [ id, sum ] } else if(aggregation === "1") { partialResult = [ id, sum/peopleFiltered.length ] } // extend this 'if...else if' to add new calculation for different aggregation result.push(partialResult) }) console.log(result)

Answer 3

 let people=[{aggregationType: "1",coefficient: 0.03,id: "p1",name: "petter",type: "Number",value: 14},{aggregationType: "0",coefficient: 1,id: "p2",name: "mary",type: "Number",value: 24},{aggregationType: "1",coefficient: 0.03,id: "p1",name: "Amee",type: "Number",value: 32},{aggregationType: "0",coefficient: 1,id: "p2",name: "Mtp",type: "Number",value: 33},{aggregationType: "1",coefficient: 0.03,id: "p1",name: "Louis",type: "Number",value: 44}]; var data = {}; people.forEach(function(item, index){ data[item.id] = data[item.id] || {}; data[item.id]['result'] = data[item.id]['result'] || 0; data[item.id]['values'] = data[item.id]['values'] || []; data[item.id]['values'].push(item.value) if('1' === item.aggregationType) { data[item.id]['result'] = data[item.id]['values'].reduce(function(a,b){ return a + b},0) / data[item.id]['values'].length * item.coefficient; } else { data[item.id]['result'] = data[item.id]['result'] + item.value } }); console.log(data.p1.result) console.log(data.p2.result)