Merge/flatten multidimensional array and remove duplicates Javascript

Question

I have a multidimensional array that looks like this:

var workouts = [
  [0, Object, 0, 0, 0],
  [Object, 0, 0, 0, 0],
  [0, 0, 0, Object, 0]
];

I'd like to flatten/merge the array and remove the duplicates. The result should look something like this:

[Object, Object, 0, Object, 0]

Is it possible to perform?

How are you defining removing duplicates? Why is 0 in your result twice, is that not a duplicate? What have you tried? — UnknownFury, Aug 11 '16 at 10:49
only 2 zeroes are there in your expected Output.. Is that right? It supposed to have 3 zeroes isn't it? — Rajaprabhu Aravindasamy, Aug 11 '16 at 10:51
Yes, it should be 2 zeros in the expected output. My plan is to loop the expected output and then render different elements depending on the 0 / the object. — malen, Aug 11 '16 at 10:55
Are you mapping the indices of inner arrays and mark the ones with the object if an inner array has an onbect at that index or 0 if not? — Redu, Aug 11 '16 at 11:00

score 2 · Accepted Answer · answered Aug 11 '16 at 10:58

My understanding is that you want to keep the first encountered object in a given column if it exists.

You can do that with .map() and .reduce():

var workouts = [
  [0, {id:1}, 0, 0, 0],
  [{id:2}, 0, 0, 0, 0],
  [0, 0, 0, {id:3}, 0]
];

var res = workouts.reduce(function(a, b) {
  return b.map(function(e, i) { return a[i] instanceof Object ? a[i] : e; });
}, []);


console.log(JSON.stringify(res));

score 1 · Answer 2 · answered Dec 09 '19 at 14:32

Late for the party, but I still want to make use of:

Array.prototype.flat() for reducing the dimension to 1,
Set for removing dupes
Spread Syntax for getting array out of that set.
JSON.stringify and parse back for handling dupes of Objects.

Here's the code and a very inspirational posts 1 and 2:

const myArray = [
  [0, {id:1}, 0, 0, 0],
  [{id:2}, 0, 0, 0, 0],
  [0, 0, 0, {id:2}, 0]
]

const myFlatArray = myArray.flat()
const result = [...new Set(myFlatArray.map(JSON.stringify))].map(JSON.parse)

console.log(JSON.stringify(result))

Note: ES6 must be supported for this solution

score 0 · Answer 3 · answered Aug 11 '16 at 11:04

var workouts = [
  [0, {id:1}, 0, 0, 0],
  [{id:2}, 0, 0, 0, 0],
  [0, 0, 0, {id:3}, 0]
];

function flattenArray (array){
  var newArray = [];
  for (i=0; i<array.length; i++){
    var subArray = array[i];
    for (ii=0; ii<subArray.length; ii++){
      if (newArray.indexOf(subArray[ii]) == -1){
      newArray.push(subArray[ii]);
      }
    }
  }
  return newArray;
}
console.log(flattenArray(workouts));

http://codepen.io/anon/pen/WxLrqL

score 0 · Answer 4 · answered Aug 11 '16 at 11:08

0

I would do like this;

var workouts = [[0, {a:1}, 0, 0, 0],
                [{b:2}, 0, 0, 0, 0],
                [0, 0, 0, {c:3}, 0]
               ],
      result = workouts.reduce((p,c) => p = c.map((e,i) => e || p[i] || 0 ),[])
console.log(result);

answered Aug 11 '16 at 11:08

Redu

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I don't understand anything :( all the inline code and non explanatory variables makes its super hard to read – Piotr Kula Aug 07 '18 at 09:09

Merge/flatten multidimensional array and remove duplicates Javascript

4 Answers4