How to shuffle the rows of a 2d array in C#

November 13, 2021

For example, I have 2d array:

int[,] array = new int[3,3] {{1,2,3}, {4,5,6} {7,8,9}}

1 2 3
4 5 6
7 8 9

I want to shuffle the order of the row like this

4 5 6
7 8 9
1 2 3

>Solution :

You can use the Fisher-Yates shuffle to swap the "rows" of the array. I used this answer for a 1d array and converted it to work with a 2d array:

public static void Shuffle(Random random, int[,] arr)
{
    int height = arr.GetUpperBound(0) + 1;
    int width = arr.GetUpperBound(1) + 1;

    for (int i = 0; i < height; ++i)
    {
        int randomRow = random.Next(i, height);
        for (int j = 0; j < width; ++j)
        {
            int tmp = arr[i, j];
            arr[i, j] = arr[randomRow, j];
            arr[randomRow, j] = tmp;
        }

    }
}

Try it online