convert array to object using lodash

Question

I need to convert an array or an array of arrays to an object with keys named from an array of names. Example:

//given names
    names = ['first', 'second', 'third', 'fourth'] 
//array
    param = [1, 2, 3, 4] 
//becomes 
    result = {first: 1, second: 2, third: 3, fourth: 4}

//array of arrays 
    param = [
      [1, 2, 3, 4],
      [-4, 3, 1, 32],
    ]
//becomes
    result = [
      {first: 1, second: 2, third: 3, fourth: 4},
      {first: -4, second: 3, third: 1, fourth: 32},
    ]

My current solution is this:

    var names = ['first', 'second', 'third', 'forth'];

    function arrayToObject(array, names) {
      var result = {};
      for (var i = 0; i < array.length; i++) {
        if (typeof array[i] === 'object') {
          result[i] = arrayToObject(array[i], names);
          continue;
        }
        result[names[i]] = array[i];
      }
      return result;
    }

The problem with this solution is that it always returns an object, though it should return an array of objects when I pass in an array of arrays. Is there a way to do this with lodash and I'm not seeing it?

then it is ok. you declare result as object. write if statement: result = [] if array, result = {} if hash — Alexey Obukhov
– Alexey Obukhov, Commented Mar 18, 2016 at 12:03
Thanks, I knew that. That's why I'm asking for something like a lodash solution, for it to be as concise as possible :) — Kek
– Kek, Commented Mar 18, 2016 at 12:11

Andy · Accepted Answer · 2016-03-18 12:24:43Z

7

Vanilla JS: A function that creates an object from an array:

function toObj(arr) {
  return arr.reduce(function(p, c, i) {
    p[names[i]] = c;
    return p;
  }, {});
}

Used with map:

var out = arr.map(toObj);

DEMO

edited Mar 18, 2016 at 12:24

answered Mar 18, 2016 at 12:03

Andy

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1 Comment

Kek Over a year ago

Clever, I didn't think of using map together with reduce

Mr. Polywhirl · Accepted Answer · 2016-03-18 12:16:05Z

6

You can use _.zipObject() to zip up two arrays into an object. You are essentially mapping CSV data, with headers, to JavaScript objects.

You can try to search for JavaScript CSV converters. You may find some interesting results.

// Given names
var names = [ 'first', 'second', 'third', 'fourth' ]; 
// Array
var param = [ 1, 2, 3, 4 ];
// Becomes 
var result = _.zipObject(names, param);

document.body.innerHTML = JSON.stringify(result, null, 2);

// Array of arrays 
var param = [
  [ 1, 2, 3, 4 ],
  [ -4, 3, 1, 32 ],
];
// Becomes
var result = _.chain(param).map(function(p) {
	return _.zipObject(names, p)
}).value();

document.body.innerHTML += '\n\n' + JSON.stringify(result, null, 2);

body {
  font-family: monospace;
  white-space: pre;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.6.1/lodash.min.js"></script>

edited Mar 18, 2016 at 12:16

answered Mar 18, 2016 at 12:10

Mr. Polywhirl

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2 Comments

Kek Over a year ago

I'll look into CSV converters, thanks :). Though while this is indeed a solution in lodash I'll go with Andys solution due to it being as concise as yours and most importantly vanilla.

Mr. Polywhirl Over a year ago

Well, I would have used reduce as well, as it is trivial, but you asked for a lodash solution...

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