How to loop a 2D array and store objects?

Question

Im trying to store objects into the array. I tried using the 2D array loop and im not getting the right results that i want. Can i know what is wrong and how do i fix it? Its printing 15 times instead of 5 times just like how i want the output stated below.

Input:

var places = ['Place A', 'Place B', 'Place C', 'Place D', 'Place E'];
var data = [];
var results = [
  [ '1.3784294469999998', '103.9424764', '519498' ],
  [ '1.325617641', '103.67841059999999', '629117' ],
  [ '1.3835802030000002', '103.7707748', '670445' ],
  [ '1.322595392', '103.8136987', '258748' ],
  [ '1.3061957990000002', '103.828509', '238884' ]
]

Output I want:

[
  [ places: 'Place A', lat: '1.3784294469999998', lon: '103.9424764', zip: '519498' ],
  [ places: 'Place B', lat: '1.325617641', lon: '103.67841059999999', zip: '629117' ],
  [ places: 'Place C',lat: '1.3835802030000002', lon: '103.7707748', zip: '670445' ],
  [ places: 'Place D',lat: '1.322595392', lon: '103.8136987', '258748' ],
  [ places: 'Place E',lat: '1.3061957990000002', lon: '103.828509', zip: '238884' ]
]

Code:

  for (i = 0; i < results.length; i++) {
    for (j = 0; j < results[i].length; j++) {
      data.push({ places: places[i], lat: results[i][j], lon: results[i][j], zip: [i][j]});
    }
  }

CertainPerformance · Accepted Answer · 2020-03-15 06:01:03Z

You need a single loop, not a nested loop:

var places = ['Place A', 'Place B', 'Place C', 'Place D', 'Place E'];
var data = [];
var results = [
  [ '1.3784294469999998', '103.9424764', '519498' ],
  [ '1.325617641', '103.67841059999999', '629117' ],
  [ '1.3835802030000002', '103.7707748', '670445' ],
  [ '1.322595392', '103.8136987', '258748' ],
  [ '1.3061957990000002', '103.828509', '238884' ]
];
for (i = 0; i < results.length; i++) {
  data.push({ places: places[i], lat: results[i][0], lon: results[i][1], zip: results[i][2]});
}
console.log(data);

Or, perhaps more readably with .map and destructuring:

var places = ['Place A', 'Place B', 'Place C', 'Place D', 'Place E'];
var results = [
  [ '1.3784294469999998', '103.9424764', '519498' ],
  [ '1.325617641', '103.67841059999999', '629117' ],
  [ '1.3835802030000002', '103.7707748', '670445' ],
  [ '1.322595392', '103.8136987', '258748' ],
  [ '1.3061957990000002', '103.828509', '238884' ]
];
const data = results.map(
  ([lat, lon, zip], i) => ({ places: places[i], lat, lon, zip })
);
console.log(data);

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

What is happening in your code

Currently with your for loop for every element in places it will go over every nested element in results. This is how you get your 15 entries (5 placed times 3 results)

Solution:

for (i = 0; i < results.length; i++) {
    data.push({ places: places[i], lat: results[i][0], lon: results[i][1], zip: [i][2]});
}

This will loop over all your places and add the results in. It is almost what you had, but without the nested for loop and j replaced for the index of lat, lon and zip respectively.

edited Jun 20, 2020 at 9:12

CommunityBot

11 silver badge

answered Mar 15, 2020 at 6:13

Phy

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1 Comment

scorezel789 Over a year ago

Thanks for your explanation! I think this is the clearest and very simple to understand. I was thinking too hard when its actually quite simple. Thank you for your help!

Eli Johnson · Accepted Answer · 2020-03-15 06:14:07Z

0

Put your code in a function and return the results like so:

function combine() {
  let data = []
  for (i = 0; i < results.length; i++) {
    for (j = 0; j < results[i].length; j++) {
      data.push({ places: places[i], lat: results[i][j], lon: results[i][j], zip: [i][j]});
    }
  }
  return data
}

answered Mar 15, 2020 at 6:14

Eli Johnson

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