combine object arrays recursively javascript/ typescript

Question

I have n number of arrays structured like

[{val_1: 2}, {val_1: 3}];
[{val_2: 2}];
[{val_3: 1}];

etc.

I want to create a single array structured like

[{val_1: 2, val_2: 2, val_3: 1}, {val_1: 3, val_2: 2, val_3: 1}]

in which all arrays are compared and every single possible output is produced. In the below code I have 3 arrays. One with 4 values, 2 values, and 3 values. I want it to return 24 different arrays showing all possible combinations.

      var val_1 = 3
  var val_2 = 2
  var val_3 = 1
  var total_val = 3;
  var useable = 50;

  var array_1 = new Array();
  var array_2 = new Array();
  var array_3 = new Array();
  var array_1_c = new Array();
  var array_2_c = new Array();
  var array_3_c = new Array();

  for(val_1; val_1 <= total_val && val_1 <= useable; val_1+=1){
    array_1 = [{val_1}];
    array_1.map(test =>{
      return{val_1}
    }).forEach(test => array_1_c.push(test));
  };
  var val_1 = 2
  for(val_1; val_1 >= 0; val_1-=1){
    array_1 = [{val_1}];
    array_1.map(test =>{
      return{val_1}
    }).forEach(test => array_1_c.push(test));
  };

  for(val_2; val_2 <= total_val && val_2 <= useable; val_2+=1){
    array_2 = [{val_2}];
    array_2.map(test =>{
      return{val_2}
    }).forEach(test => array_2_c.push(test));
  };
  for(val_3; val_3 <= total_val && val_3 <= useable; val_3+=1){
    array_3 = [{val_3}];
    array_3.map(test =>{
      return{val_3}
    }).forEach(test => array_3_c.push(test));
  }; console.log(array_1_c);console.log(array_2_c);console.log(array_3_c);

how would something like this be accomplished? The permute function seems to be the way to go, but I can't find a way to output every single combination. If creating multiple million combinations should I go a different route than using an object array.

Thanks!

Hi, can you please explain how are you evaluating 12 combinations from arrays of sizes 4, 2 & 3? — Nikhil Aggarwal
– Nikhil Aggarwal, Commented Apr 21, 2020 at 17:15
Sorry I meant 24 combinations*. 4 * 2 * 3 = 24. The result needs to be a combination of each value in order. — Andrew M
– Andrew M, Commented Apr 21, 2020 at 17:32
I guess you need a solution of Cartesian product, not permutations. Take a look at: stackoverflow.com/questions/56972012/… This question have a relevant answer to your problem. — AlexZeDim
– AlexZeDim, Commented Apr 21, 2020 at 18:05

Nina Scholz · Accepted Answer · 2020-04-21 17:20:04Z

2

You could take an algorithm for a cartesian product by using arrays of objects.

The result is an array of object with all properties of the given data.

const
    getCartesian = array => array.reduce((a, b) => a.reduce((r, v) => r.concat(b.map(w => ({ ...v, ...w }))), [])),
    all = [[{ val_1: 2 }, { val_1: 3 }], [{ val_2: 2 }], [{ val_3: 1 }]],
    cartesian = getCartesian(all);
  
console.log(cartesian);

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

answered Apr 21, 2020 at 17:20

Nina Scholz

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