Javascript convert multi-dimensional array to unique array of items

Question

I'm trying to come up with an algorithm that will take any multidimensional array and convert it to an array with unique items:

Example:

  var arr = [
       ["bananas", "oranges"],
       ["cars", "trucks", "airplanes"],
       ["Jim", "Bob", "David", "Diana"]
  ];

  // I need to create an array that will contain a unique record of each item in the array

  /*
  NEED TO OUTPUT TO
  newArr = [
       ["bananas", "cars", "Jim"],
       ["bananas", "cars", "Bob],
       ["bananas", "cars", "David],
       ["bananas", "cars", "Diana],
       ["bananas", "trucks", "Jim"],
       ["bananas", "trucks", "Bob],
       ["bananas", "trucks", "David],
       ["bananas", "trucks", "Diana],
       ["bananas", "airplanes", "Jim"],
       ["bananas", "airplanes", "Bob],
       ["bananas", "airplanes", "David],
       ["bananas", "airplanes", "Diana],  
       ["oranges", "cars", "Jim"],
       ["oranges", "cars", "Bob],
       ["oranges", "cars", "David],
       ["oranges", "cars", "Diana],
       ["oranges", "trucks", "Jim"],
       ["oranges", "trucks", "Bob],
       ["oranges", "trucks", "David],
       ["oranges", "trucks", "Diana],
       ["oranges", "airplanes", "Jim"],
       ["oranges", "airplanes", "Bob],
       ["oranges", "airplanes", "David],
       ["oranges", "airplanes", "Diana]
     ];
  */

The above is just an example. I need this algorithm to handle any size array. I have not got very far at all. Any help would be greatly appreciated.

Here's what I have so far - its hardly much and not pretty (FYI - I am open to using jQuery if it helps):

function foo() {
  
  var arr = [
  ["bananas", "oranges"],
  ["cars", "trucks", "airplanes"],
  ["Jim", "Bob", "David", "Diana"]
];

  
  var i = 0, j = 0;
  
  //Define the containing array
  var newArr = [];
  
  //Used to calculate the total unique entries (24 in this example: 2 * 3 * 4)
  var totalObjects = 1;
  
  //Calculate total unique objects
  for (i = 0; i < arr.length; i++) {
    totalObjects *= arr[i].length;
  }
  
  //Identify the new array to contain 24 arrays each with 3 entries
  for (i = 0; i < totalObjects; i++) {
    newArr.push(new Array(arr.length));
  }
  
  
  for (i = 0; i < newArr.length; i++) {    
    for (j = 0; j < newArr[i].length; j++) {
      newArr[i][j] = arr[j][i];
    }    
  }
  
}

foo();

Do you mean you want to form an array of arrays, where each subarray in the result (the result is an array) is a unique permutation containing 1 member of each of the original subarrays? — CSSBurner, May 31 '18 at 15:26
As david said, it looks you want permutations not unique items — andrewgi, May 31 '18 at 15:27
jQuery won't help. It's for DOM manipulation, here you need only pure JS. — Jeremy Thille, May 31 '18 at 15:29

score 8 · Accepted Answer · answered May 31 '18 at 15:29

You could use a reduce where each item of the same array is collected with an item of the other arrays. Then the result is returned.

var array = [["bananas", "oranges"], ["cars", "trucks", "airplanes"], ["Jim", "Bob", "David", "Diana"]],
    result = array.reduce(
        (a, b) => a.reduce((r, v) => r.concat(b.map(w => [].concat(v, w))), [])
    );
    
console.log(result);

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

Javascript convert multi-dimensional array to unique array of items

1 Answers1