How can i change the index of a matrix with values of arraylists?

Natalia Sacco :

I'm importing some values from matlab in a java code (Eclipse). I want to change the index of the matrix with the lists that i have in java. How can i do that?

'''

public class ConMat {

 public static void main(String[] args) throws Exception {

        int n = 2;// number of requests
        int K=2;
        int F=2*n;
        int N=2*n;

        LinkedList<Integer> Origin = new LinkedList<Integer>();
        Origin.add(0,1);
        Origin.add(1,2);
        Origin.add(2,3);

        LinkedList<Integer> Dest = new LinkedList<Integer>();
        Dest.add(0,2);
        Dest.add(1,3);
        Dest.add(2,1);


        LinkedList<Integer> U = new LinkedList<Integer>();
        U.addAll(Origin);
        U.addAll(Dest);

        LinkedList<Integer> Z = new LinkedList<Integer>();
         Z.addAll(Origin);
         Z.addAll(Dest);
       //  Z.add(4,0);
        // Z.add(5,5);


     MatlabEngine eng1 = MatlabEngine.startMatlab();
    eng1.eval("addpath('.\\MATLAB\\Dial')");
    int D=3;
    double[][] OD_incr=new double[D][D] ;
    double[][]odmatrix=new double[D][D];
    double [] origins= {1,2,3};
    double [] destinations= {2,3,1};
    double []scaling= {2};
    double[][]roots = eng1.feval("Dial_java",OD_incr,origins,destinations,scaling);



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

I obtain this:

 [[0.5, 0.4791428571428572, 0.0], [0.0, Infinity, Infinity], [0.4791428571428572, 0.0, Infinity]]

I want to create a matrix with these values and the the index equals to Origin and Dest.

For example:

  double[][] c = new double[][];
  for( int i:Origin){
    for(int j:Dest){
     c[i][j]=roots[i][j];
     }
      }

How can i do that?

WJS :

I'm not quite certain I understand. But matrices in Java are 0 based. So you would need to subtract one from the matlab matrix index.

Try this. I'm not certain how you want to apply Origin and Dest.

         int D = 3;
         double[][] c = new double[D][D];
         for( int i= 0; i < D; i++){
              for (int j = 0; j < D; j++) {
                 c[Dest.get(i)-1][Dest.get(j)-1]
                    =roots[Origin.get(i)-1][Origin.get(j)-1];
              }
         }

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

Here is a sample of what I was doing so you can apply the technique yourself. See if this does what you want. It uses sample data from your post since I don't have MatLab.

        int D = 3;
        double roots[][] = { { 0.5, 0.4791428571428572, 0.0 },
                {0.0,Double.POSITIVE_INFINITY,Double.POSITIVE_INFINITY},
                { 0.4791428571428572, 0.0, Double.POSITIVE_INFINITY, } };

        System.out.println("Before copying");
        for (double[] a : roots) {
            System.out.println(Arrays.toString(a));
        }

        double[][] c = new double[D][D];
        for (int i = 0; i < D; i++) {
            for (int j = 0; j < D; j++) {
                c[Dest.get(i)-1][Dest.get(j)-1] = roots[Origin.get(i)-1] 
                          [Origin.get(j)-1]; 
            }
        }

        System.out.println("\nAfter copying");
        for (double[] a : c) {
            System.out.println(Arrays.toString(a));
        }