creating distance matrix from 2D array

Question

I have a 2D Array (inputMatrix with x rows and y columns) and need to subtract all vectors(rows) with eachother.

Here's the input:

1,5
3,7
2,3
6,5
4,7

The output(a distance matrix) should look like:

subtraction[0][0] = {0,0} // first row - first row
subtraction[0][1] = {-2,-2} // first row - 2nd row -> {1,5}-{3,7}=-2,2
subtraction[0][2] = {-1,2} // first row - 3rd row 
...
subtraction[4][2] = {2,4}
subtraction[4][3] = {-2,2}
subtraction[4][4] = {0,0}

However i'm having a problem on storing the values, since subtraction[row][col] values are being overwritten on the "col for-loop". Also a note, each subtraction index is getting as output another array.

for(int row = 0; row < inputMatrix.length; row++){
            for(int col = 0; col < inputMatrix[0].length; col++){
                subtraction[row][col] = inputMatrix[0][row] - inputMatrix[row][col];
                System.out.print(subtraction[row][col] + " ");
            }
        System.out.print("\n");
    }

Answer 1

Based on your description of the output, you need a 3-dimensional array to store the output, since for each pair of input rows, you are producing an output row.

for(int row1 = 0; row1 < inputMatrix.length; row1++){
   for(int row2 = 0; row2 < inputMatrix.length; row2++){
        for(int col = 0; col < inputMatrix[0].length; col++){
            subtraction[row1][row2][col] = inputMatrix[row1][col] - inputMatrix[row2][col];
        }
    }
}

If you must have a two dimensional output, you can flatten the output :

int outputRow = 0;
for(int row1 = 0; row1 < inputMatrix.length; row1++){
   for(int row2 = 0; row2 < inputMatrix.length; row2++){
        for(int col = 0; col < inputMatrix[0].length; col++){
            subtraction[outputRow][col] = inputMatrix[row1][col] - inputMatrix[row2][col];
        }
        outputRow++;
    }
}

Answer 2

subtraction[row][col] = inputMatrix[0][row] - inputMatrix[**row**][**col**];

您在这里混合了索引。