How to convert into multidimensional array in angularjs

Question

I need some help to convert JSON array to multidimensional array, I keep getting stuck.

I am also tried with _.groupBy in underscore.js but it's not working for the nested array.

If any possible to convert from the following

[{
  "subject": "physics",
  "student_id": "2569",
  "values": "0.152,0.228,0.218"
}, {
  "subject": "maths",
  "student_id": "1236",
  "values": "0.146,0.22,0.212"
}, {
  "subject": "chemistry",
  "student_id": "4569",
  "values": "0.159,0.234,0.224"
}, {
  "subject": "physics",
  "student_id": "1478",
  "values": "0.16,0.235,0.225"
}]

Expected Result should be

{ 'physics': {
    '2569': "0.152,0.228,0.218",
    '1478': "0.16,0.235,0.225"
},
'maths': {
    '1236': "0.146,0.22,0.212"
},
'chemistry': {
    '4569': "0.159,0.234,0.224"
} }

Please provide me with a simple solution.

spirift · Accepted Answer · 2018-12-10 13:56:08Z

4

Looks like you want to change an array into an object. Array.prototype.reduce is your friend for this.

const list = [{
  "subject": "physics",
  "student_id": "2569",
  "values": "0.152,0.228,0.218"
}, {
  "subject": "maths",
  "student_id": "1236",
  "values": "0.146,0.22,0.212"
}, {
  "subject": "chemistry",
  "student_id": "4569",
  "values": "0.159,0.234,0.224"
}, {
  "subject": "physics",
  "student_id": "1478",
  "values": "0.16,0.235,0.225"
}]

const data = list.reduce((reduction, item) => {
  if (reduction[item.subject]) {
    reduction[item.subject][item.student_id] = item.values 
  } else {
    reduction[item.subject] = {
      [item.student_id]: item.values 
    }
  }
  return reduction
}, {})
console.log(data)

answered Dec 10, 2018 at 13:56

spirift

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Comments

georgeawg · Accepted Answer · 2018-12-10 16:47:26Z

0

const list = [{
  "subject": "physics",
  "student_id": "2569",
  "values": "0.152,0.228,0.218"
}, {
  "subject": "mathss",
  "student_id": "1236",
  "values": "0.146,0.22,0.212"
}, {
  "subject": "chemistry",
  "student_id": "4569",
  "values": "0.159,0.234,0.224"
}, {
  "subject": "physics",
  "student_id": "1478",
  "values": "0.16,0.235,0.225"
}]
reduction  = {}
list.map((a, b) => {
	if(reduction[a.subject])
		reduction[a.subject][a.student_id] = a.values;
	else
		reduction[a.subject] = {[a.student_id] : a.values};
	return reduction;
})
console.log(reduction);

edited Dec 10, 2018 at 16:47

georgeawg

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answered Dec 10, 2018 at 15:40

Haris

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Comments

Akrion · Accepted Answer · 2018-12-10 21:56:08Z

0

You can solve this in a concise way via Array.reduce and some ES6 destructuring:

const data = [{ "subject": "physics", "student_id": "2569", "values": "0.152,0.228,0.218" }, { "subject": "maths", "student_id": "1236", "values": "0.146,0.22,0.212" }, { "subject": "chemistry", "student_id": "4569", "values": "0.159,0.234,0.224" }, { "subject": "physics", "student_id": "1478", "values": "0.16,0.235,0.225" }]

const result = data.reduce((a, {subject, student_id, values}) => {
  a[subject] = a[subject] || {}
  a[subject][student_id] = values
  return a
}, {})

console.log(result)

answered Dec 10, 2018 at 21:56

Akrion

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Comments

Ori Drori · Accepted Answer · 2018-12-10 23:03:50Z

0

You can use lodash's _.setWith() (to force object creation for numerical keys) with Array.reduce():

const data = [{"subject":"physics","student_id":"2569","values":"0.152,0.228,0.218"},{"subject":"maths","student_id":"1236","values":"0.146,0.22,0.212"},{"subject":"chemistry","student_id":"4569","values":"0.159,0.234,0.224"},{"subject":"physics","student_id":"1478","values":"0.16,0.235,0.225"}];

const fn = arr =>
  arr.reduce((r, o) => 
    _.setWith(r, [o.subject, o.student_id], o.values, Object)
  , {});

const result = fn(data);

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

edited Dec 10, 2018 at 23:03

answered Dec 10, 2018 at 15:31

Ori Drori

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