Javascript - How to push an array to a multidimensional array

Question

I trying to push an array I've generated to a multidimensional array, and for some reason the value of all the other positions in the array's values, are the same as the value I just pushed.

For example: I do

var grades = [];

for(var i = 0; i < num_qes + 1; i++){
        var grade = [0, 0, 0, 0];

        grade[0] = i;
        for(var n = 0; n < num_qes+ 1; n++){
            grade[1] = n;
            for(var f = 0; f < num_qes+ 1; f++){
                grade[2] = f;
                for(var t = 0; t < num_qes+ 1; t++){
                    grade[3] = t;

                    allGrad = grade[0] + grade[1] +  grade[2] + grade[3];

                    //println(allGrad);

                    if(allGrad === num_qes){
                        grades.push(grade);
                    }
                }
            }
        }

Here at the end I check to see if all of the values in my generated array are exactly equal to the number of questions.

  if(allGrad === num_qes){
     grades.push(grade);
  }

Let's say that grade = [9, 1, 0, 0], when I push this value to the multidimensional array, grades, all the values change to [9, 1, 0, 0]. So the multidimensional array looks like this: [[9, 1, 0, 0], [9, 1, 0, 0], [9, 1, 0, 0]], when it SHOULD look like this: [[9, 0, 0, 1], [9, 0, 1, 0], [9, 1, 0, 0]].

I hope what I said make senses, and thanks in advance for ansnewing.

The jsfiddle is right here

Could you add a jsfiddle with a not-working example for better understanding please. — Kiril
– Kiril, Commented Jan 11, 2016 at 20:53
Are you trying to get all combinations where the sum of the 4 values equals num_qes? — Quantumplate
– Quantumplate, Commented Jan 11, 2016 at 20:58
The jsfiddle is right here, I'm trying to get the page to display the results. — TheRailsRouter
– TheRailsRouter, Commented Jan 11, 2016 at 21:10

Quantumplate · Accepted Answer · 2016-01-11 21:20:27Z

1

Is this what you are after?

var grades = [];
var num_qes = 4;

for(var i = 0; i <= num_qes; i++){
  for(var n = 0; n <= num_qes; n++){
    for(var f = 0; f <= num_qes; f++){
      for(var t = 0; t <= num_qes; t++){
        var sum = i + n + f + t;

        if(sum === num_qes){
          console.log(i + ',' + n + ',' + f + ',' + t);

          var grade = [i, n, f, t];
          grades.push(grade);
        }
      }
    }
  }
}

Notes:

I've replaced i < num_qes + 1 with i <= num_ques for simplicity
Only creating the grade array in the inner loop when your condition is met (makes it much more readable)
Summing the numbers directly rather than reading from the grade array you've just populated (again more readable)
Using console.log() to output results that match criteria

Results in console look like this...

0,0,0,4
0,0,1,3
0,0,2,2
0,0,3,1
0,0,4,0
0,1,0,3
0,1,1,2
0,1,2,1
0,1,3,0
etc

answered Jan 11, 2016 at 21:20

Quantumplate

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4 Comments

TheRailsRouter Over a year ago

I'll try this out, Thank!

TheRailsRouter Over a year ago

I still have other problems, but I'll figure those out on my own

Quantumplate Over a year ago

What are your other problems? Writing results to the html page?

TheRailsRouter Over a year ago

I figured out the problem.

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