如何在 JavaScript 数组中分组、计算总和并获取平

How to group by, calculate sum and get average in JavaScript array?(如何在 JavaScript 数组中分组、计算总和并获取平均值?)

问题描述

我有一个对象数组

 const users = [
     { group: 'editor', name: 'Adam', age: 23 },
     { group: 'admin', name: 'John', age: 28 },
     { group: 'editor', name: 'William', age: 34 },
     { group: 'admin', name: 'Oliver', age: 28' }
 ];

预期结果:

//sum
 sumAge = {
 editor: 57,  // 23+34
 admin: 56    // 28+28
}

//average
avgAge = {
   editor: 28.5,  // (23+34) / 2
   admin: 28    //(28+28)/2
}

我使用 reduce() 方法将数组中的对象按组"分组并计算总和:

I use reduce() method to group the objects in an array by 'group' and calulate sum:

let sumAge = users.reduce((group, age) => {
    group[age.group] = (group[age.group] || 0) + age.age || 1;
    return group;
}, {})
console.log('sumAge', sumAge); // sumAge: {editor: 57, admin: 56} 
done!

如何通过键组"对数组的对象进行分组并计算平均值?.我试过了:

How to group object of Array by key 'group' and calulate average?. I tried:

let ageAvg= users.reduce((group, age) => {
      if (!group[age.group]) {
      group[age.group] = { ...age, count: 1 }
         return group;
      }
      group[age.group].age+= age.age;
      group[age.group].count += 1;
      return group;
      }, {})
const result = Object.keys(ageAvg).map(function(x){
     const item  = ageAvg[x];
     return {
         group: item.group,
         ageAvg: item.age/item.count,
     }
 })
console.log('result',result);
/*
result=[
    {group: "editor", ageAvg: 28.5}
    {group: "admin", ageAvg: 28}
]

但预期结果:

result = {
   editor: 28.5,  // (23+34) / 2
   admin: 28    //(28+28)/2
}

推荐答案

您可以简单地使用 reduce 来获取 age groups 的 total.

You could simply use reduce to get the total of age groups.

并使用 object.keys length 从 getAvg 函数中获取作为新对象的总数的平均值.

And use object.keys length to get the average of your total as new object from getAvg function.

演示:

const users = [{
    group: 'editor',
    name: 'Adam',
    age: 23
  },
  {
    group: 'admin',
    name: 'John',
    age: 28
  },
  {
    group: 'editor',
    name: 'William',
    age: 34
  },
  {
    group: 'admin',
    name: 'Oliver',
    age: 28
  }
];

const sumId = users.reduce((a, {
  group,
  age
}) => (a[group] = (a[group] || 0) + age, a), {});

console.log(sumId); //{editor: 57, admin: 56}

//Average
const getAvg = (x) => {
  const item = {}
  const count = Object.keys(x).length
  Object.keys(x).map(function(y) {
    item[y] = sumId[y] / count
  })
  return item
}
console.log(getAvg(sumId)); //{editor: 28.5, admin: 28}

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