Initialize the Columns of an Array in Java

Question

I have three arrays of equal lengths that I combine (as I will sort them on column c later):

double abc[][] = {
    Arrays.copyOf(a, a.length),
    Arrays.copyOf(b, a.length),
    Arrays.copyOf(c, a.length)
};

When I call

System.out.println(Arrays.deepToString(abc));

I receieve:

[[4.0, 2.0, 1.3333333333333333, 5.0, 2.5, 1.6666666666666667 ....

However, I would prefer something like:

[[1.0, 1.0, 4.0], [2.0, 2.0, 5.0], [3.0, 3.0, 7.0]]

This is possible using double singlets

double test[][] = {{1,1,4},{2,2,5},{3,3,7}};

How can I populate/initialize three columns using three double[ ]?

---

EDIT:

Solution based on vojta's answer:

double abcT[][] = new double[abc[0].length][abc.length];
    for (int i = 0; i < abc.length; i++) {
         for (int j = 0; j < abc[0].length; j++) {
            abcT[j][i] = abc[i][j];
         }
      }
System.out.println(Arrays.deepToString(abcT));

Answer 1

I think there is no one-line solution of your problem, unfortunately. You will have to use some homemade code:

static <T> T[][] createMatrix(T[]... columns) {
  if (columns== null || columns.length == 0)
    return new T[0][0];

  int wid = columns.length;
  int ht = columns[0].length;

  T[][] result = new T[ht][wid];

  for (int x = 0; x < wid; x++) {
    for (int y = 0; y < ht; y++) {
      result[y][x] = columns[x][y];
    }
  }
  return result;
}

I hope it was useful.

Answer 2

I finally reached this more elegant solution:

    for (int i = 0; i < a.length; i++){
            abc[0][i] = a[i];
            abc[1][i] = b[i];
            abc[2][i] = c[i];
    }

Although it is not a general solution for n[], this avoids the need to make intermediate copies of the original arrays. And then I just swap the for-loops for row and column:

    for (int j = 0; j < abc[0].length; j++) {
        for (int i = 0; i < abc.length; i++) {
            System.out.print(abc[i][j] + " ");
        }
        System.out.print("\n");
    }

Note: This solution does not store in the intended R:C format, but retrieves in C:R.