Transform Array of objects into 2D array

Question

I want transform an array of objects into 2D array (array of arrays). I try with map and Object.keys(), but I want push the first value of each objects into the first array, the second value of each objects into the second array, etc ... Thank you for your answers.

The good result

[
  ['2', '5', '8', '10', '12'],
  ['4', '10', '16', '20', '24'],
  ['6', '15', '24', '30', '36'],
  ['10', '25', '40', '50', '60']
]

The actual result

[
  ['2', '4', '6', '10'],
  ['5', '10', '15', '25'],
  ['8', '16', '24', '40'],
  ['10', '20', '30', '50'],
  ['12', '24', '36', '60']
]

let obj = [
  {
    line1: '2',
    line2: '4',
    line3: '6',
    line4: '10'
  }, {
    line1: '5',
    line2: '10',
    line3: '15',
    line4: '25'
  }, {
    line1: '8',
    line2: '16',
    line3: '24',
    line4: '40'
  }, {
    line1: '10',
    line2: '20',
    line3: '30',
    line4: '50'
  }, {
    line1: '12',
    line2: '24',
    line3: '36',
    line4: '60'
  }
];

var output = obj.map(function(obj) {
  return Object.keys(obj).map(function(key) { 
    return obj[key];
  });
});

console.log(output);

JS Objects are unordered structures - you can't have a strict order of key/values. stackoverflow.com/questions/5525795/… — RomanPerekhrest
– RomanPerekhrest, Commented Nov 29, 2017 at 12:03

Nina Scholz · Accepted Answer · 2017-11-29 12:03:55Z

You need the indices for transfoming and take the reversed indices for accessing the result set.

var array = [{ line1: '2', line2: '4', line3: '6', line4: '10' }, { line1: '5', line2: '10', line3: '15', line4: '25' }, { line1: '8', line2: '16', line3: '24', line4: '40' }, { line1: '10', line2: '20', line3: '30', line4: '50' }, { line1: '12', line2: '24', line3: '36', line4: '60' }],
    result = array.reduce((r, o, i) => {
        Object.keys(o).forEach((k, j) => (r[j] = r[j] || [])[i] = o[k]);
        return r;
    }, []);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

For a stable result, you could take the keys as array in advance.

var array = [{ line1: '2', line2: '4', line3: '6', line4: '10' }, { line1: '5', line2: '10', line3: '15', line4: '25' }, { line1: '8', line2: '16', line3: '24', line4: '40' }, { line1: '10', line2: '20', line3: '30', line4: '50' }, { line1: '12', line2: '24', line3: '36', line4: '60' }],
    keys = ['line1', 'line2', 'line3', 'line4'],
    result = array.reduce((r, o, i) => {
        keys.forEach((k, j) => (r[j] = r[j] || [])[i] = o[k]);
        return r;
    }, []);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Lalit · Accepted Answer · 2017-11-29 12:24:51Z

1

You can also use following approach.

let obj = [
  {
    line1: '2',
    line2: '4',
    line3: '6',
    line4: '10'
  }, {
    line1: '5',
    line2: '10',
    line3: '15',
    line4: '25'
  }, {
    line1: '8',
    line2: '16',
    line3: '24',
    line4: '40'
  }, {
    line1: '10',
    line2: '20',
    line3: '30',
    line4: '50'
  }, {
    line1: '12',
    line2: '24',
    line3: '36',
    line4: '60'
  }
];

var output = [];
for(var i = 0; i < obj.length; i++){
   var index = 0;
   for(var values in obj[i]){
      if(output[index] == undefined){
        output[index] = [];
      }
      output[index].push(obj[i][values]);
      index++;
   }
}

console.log(output);

answered Nov 29, 2017 at 12:24

Lalit

1,3691 gold badge8 silver badges13 bronze badges

Collectives™ on Stack Overflow

Transform Array of objects into 2D array

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related