Create all the combinations of an array with multiple sub array in Javascript

Question

I am trying to create multiple array with combination.

here is how my array looks like:

var a1 = ["1", "2", "3"];
        var a2 = ["a", "b"];
        var a3 = ["q", "w", "e"];

        var a4 = [a1, a2, a3];

I have tried one code which looks like this:

function allPossibleCases(a4) {
              if (arr.length == 1) {
                return arr[0];
              } else {
                var result = [];
                var allCasesOfRest = allPossibleCases(arr.slice(1));  // recur with the rest of array
                for (var i = 0; i < allCasesOfRest.length; i++) {
                  for (var j = 0; j < arr[0].length; j++) {
                    // console.log(arr[0][j]);
                    // console.log(allCasesOfRest[i]);
                    result.push(arr[0][j] + allCasesOfRest[i]);
                  }

                }
                return result;
              }

        }

Which is providing me correct combination it looks like this:

Array (18)
0 "1aq"
1 "2aq"
2 "3aq"
3 "1bq"
4 "2bq"
5 "3bq"
6 "1aw"
7 "2aw"
8 "3aw"
9 "1bw"
10 "2bw"
11 "3bw"
12 "1ae"
13 "2ae"
14 "3ae"
15 "1be"
16 "2be"
17 "3be"

But i want (Desired output) it to be like this :

Array (18)
    0 ["1", "a", "q"]
    1 ["2","a","q"]
    2 ["3","a","q"]
    3 ["1","b","q"]
    4 ["2","b","q"]
    5 ["3","b","q"]
    6 ["1","a","w"]
    7 ["2","a","w"]
    8 ["3","a","w"]
    9 ["1","b","w"]
    10 ["2","b","w"]
    11 ["3","b","w"]
    12 ["1","a","e"]
    13 ["2","a","e"]
    14 ["3","a","e"]
    15 ["1","b","e"]
    16 ["2","b","e"]
    17 ["3","b","e"]

Basically i am trying to achieve is a combination array instead of strings.

May be wrong but change this line result.push(arr[0][j] + allCasesOfRest[i]); to this result.push(Array.prototype.push.apply(arr[0][j], allCasesOfRest[i])); — Mykola Borysyuk
– Mykola Borysyuk, Commented Oct 1, 2016 at 13:49
i tried these, but dosent seems to be working. Any other suggestions? @varontron — user3201500
– user3201500, Commented Oct 1, 2016 at 14:03

baao · Accepted Answer · 2016-10-01 14:09:03Z

2

Just concat instead of the +:

result.push([a4[0][j]].concat(allCasesOfRest[i]));

to get what you want. You have an string and an array you want to put together - for that you can put the string in an array, then concat that array with the second array you got.

var a1 = ["1", "2", "3"];
var a2 = ["a", "b"];
var a3 = ["q", "w", "e"];

var a4 = [a1, a2, a3];

  function allPossibleCases(a4) {
    if (a4.length == 1) return a4[0];
    
      var result = [];
      var allCasesOfRest = allPossibleCases(a4.slice(1)); // recur with the rest of array
      for (var i = 0; i < allCasesOfRest.length; i++) {
        for (var j = 0; j < a4[0].length; j++) {
        
          result.push([a4[0][j]].concat(allCasesOfRest[i]));
        }

      }
      
      return result;
      
  }
  
  console.log(allPossibleCases(a4));

edited Oct 1, 2016 at 14:09

answered Oct 1, 2016 at 13:49

baao

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4 Comments

user3201500 Over a year ago

Hello, thank your for the answer but now i am getting a comma in between here is how the output looks like

["1", "a", ",", "q"], ["2", "a", ",", "q"], ["3", "a", ",", "q"], ["1", "b", ",", "q"], ["2", "b", ",", "q"], ["3", "b", ",", "q"], ["1", "a", ",", "w"], ["2", "a", ",", "w"], ["3", "a", ",", "w"], ["1", "b", ",", "w"]....

user3201500 Over a year ago

So any suggestions? So i can remove this?

baao Over a year ago

Sorry, didn't notice that one was an array.

user3201500 Over a year ago

its ok no problem, anything you can suggest?

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