go from array of objects to objects of array

Question

Incoming Data

Node is an Array of Objects

{
  "db": {
    "testing new apip": { "node": [] },
    "testing new apip 5": {
      "node": [
        {
          "id": "testing new id",
          "time": 1571679839.6459858,
          "rssi": "testing new rssi"
        },
        {
          "id": "testing new id 5",
          "time": 1571679845.8376184,
          "rssi": "testing new rssi"
        },
        {
          "id": "testing new id 55",
          "time": 1571679851.4211318,
          "rssi": "testing new rssi"
        }
      ]
    },
    "testing new apip 52": {
      "node": [
        {
          "id": "testing new id 556",
          "time": 1571679859.927497,
          "rssi": "testing new rssi"
        }
      ]
    }
  }
}

I would like to know if there is a shortcut to appending to an array without using a for loop.

Basically I want to know what is the fastest way to convert

an array of objects ==> an object of arrays.

  var data2 = {
      id: [],
      time: [],
      rssi: []
    };

This is how im doing it now:

    for (i = 0; i < data.db[AP[0]].node.length; i++) {
      data2.id.push(data.db[AP[0]].node[0].id)
      data2.time.push(data.db[AP[0]].node[0].time)
      data2.rssi.push(data.db[AP[0]].node[0].rssi)
    }

Post the example data set with desired output, then only people can give you exact answer — Code Maniac
– Code Maniac, Commented Oct 22, 2019 at 2:06
What is AP[0]? Can you please also paste the expected output? — slider
– slider, Commented Oct 22, 2019 at 2:21

Nikhil · Accepted Answer · 2019-10-22 02:22:04Z

2

One approach is to use reduce().

// Array of objects.
let node = [{ "id": "testing new id", "time": 1571679839.6459858, "rssi": "testing new rssi" }, { "id": "testing new id 5", "time": 1571679845.8376184, "rssi": "testing new rssi" }, { "id": "testing new id 55", "time": 1571679851.4211318, "rssi": "testing new rssi" } ];

let result = node.reduce((acc, curr) => {
  Object.entries(curr).forEach(([key, value]) => {
    acc[key] = acc[key] || [];
    acc[key].push(value);
  });
  
  return acc;
}, {});

// Object of arrays.
console.log(result);

answered Oct 22, 2019 at 2:22

Nikhil

6,68110 gold badges36 silver badges74 bronze badges

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

Collectives™ on Stack Overflow

go from array of objects to objects of array

an array of objects ==> an object of arrays.

This is how im doing it now:

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

an array of objects ==> an object of arrays.

This is how im doing it now:

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related