I found this (slightly changed) on sun forums .
public class Test { public static void main(String[] args) { double[][] ori = new double[][] { {1,2,3}, {4,5,6}, {7,8,9}, {10,11,12} }; double[][] res = reshape(ori,2,6); for(int i = 0;i<ori.length;i++){ for(int j = 0;j<ori[0].length;j++){ System.out.print(ori[i][j]+" "); } System.out.println(""); } System.out.println(""); for(int i = 0;i<res.length;i++){ for(int j = 0;j<res[0].length;j++){ System.out.print(res[i][j]+" "); } System.out.println(""); } } public static double[][] reshape(double[][] A, int m, int n) { int origM = A.length; int origN = A[0].length; if(origM*origN != m*n){ throw new IllegalArgumentException("New matrix must be of same area as matix A"); } double[][] B = new double[m][n]; double[] A1D = new double[A.length * A[0].length]; int index = 0; for(int i = 0;i<A.length;i++){ for(int j = 0;j<A[0].length;j++){ A1D[index++] = A[i][j]; } } index = 0; for(int i = 0;i<n;i++){ for(int j = 0;j<m;j++){ B[j][i] = A1D[index++]; } } return B; } }
test output
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 1.0 3.0 5.0 7.0 9.0 11.0 2.0 4.0 6.0 8.0 10.0 12.0