Create new array with Average of same keys in an array of objects

Question

I have an array of object as follows:

var arr=[ {"jan":2},{"jan":5},{"feb":3},{"feb":1}];

Their will be N number of objects with any combination keys jan & feb is just an example.

I need to find average of objects with similar keys so that resultant array looks like this :

var newArr=[{"jan":3.5},{"feb":2}];

Looking to achieve this without reduce method in JavaScript.

I tried to seperate out objects with similar keys so that ic an sum and average them and push in to a new aray. something like this :

arr.forEach(a=>{
   console.log(Object.keys(a))
   console.log(arr.filter(ar=>ar.hasOwnProperty(Object.keys(a)[0])))
})

But it creates multiple groups for same keys like this in console.

[ {"jan":2},{"jan":5} ]
[ {"jan":2},{"jan":5} ]
[ {"feb":3},{"feb":1} ]
[ {"feb":3},{"feb":1} ]

@NikitaMadeev I mentioned it, Need to do this without the reduce method. — Tarun Bhati
– Tarun Bhati, Commented Jul 17, 2020 at 10:54

Harmandeep Singh Kalsi · Accepted Answer · 2020-07-17 11:09:58Z

1

A code without using reduce . A bit length though but easy to understand We are using two objects , one is to store the count of the keys and other is for storing the total of the keys. result object has the average.

var arr=[ {"jan":2},{"jan":5},{"feb":3},{"feb":1}];

var count = {};
var total = {};


arr.forEach(obj => {
    var key = Object.keys(obj)[0];
    if(count.hasOwnProperty(key)){
        count[key]=count[key]+1;
    } else {
        count[key]=1;
    }
    if(total.hasOwnProperty(key)){
        total[key]=total[key]+obj[key];
    } else {
        total[key]=obj[key];
    }

})

var result = {}


Object.keys(total).forEach(key => {
    result[key] = total[key]/count[key];
})

console.log(result)

answered Jul 17, 2020 at 11:09

Harmandeep Singh Kalsi

3,3652 gold badges17 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nicholas K · Accepted Answer · 2020-07-17 12:34:16Z

1

Similar to the answer above, but makes use of a map:

var arr=[ {"jan":2},{"jan":5},{"feb":3},{"feb":1}];
let map = new Map();
let keyCount = {};

arr.forEach(e => {
  let key = Object.keys(e)[0];
  let value = Object.values(e)[0];
  
  if (map.get(key) !== undefined) {     
      map.set(key, map.get(key) + value);
      keyCount[key] = keyCount[key] + 1;
  } else {
      map.set(key, value);
      keyCount[key] = 1;
  }     
});

let newArr = [];
for (let e of map.entries()) { 
   let obj = {};
   obj[e[0]] = e[1] / keyCount[e[0]];
   newArr.push(obj);
}

console.log(newArr);

edited Jul 17, 2020 at 12:34

answered Jul 17, 2020 at 12:20

Nicholas K

15.4k8 gold badges35 silver badges59 bronze badges

Collectives™ on Stack Overflow

Create new array with Average of same keys in an array of objects

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related