How to transpose matrix?

Question

I have made 8x8 matrix using c#, and now I need to transpose the matrix. Can you help me to transpose the matrix? This is my matrix

public double[,] MatriksT(int blok)
{
    double[,] matrixT = new double[blok, blok];

    for (int j = 0; j < blok ; j++)
    {
        matrixT[0, j] = Math.Sqrt(1 / (double)blok);

    }

    for (int i = 1; i < blok; i++)
    {
        for (int j = 0; j < blok; j++)
        {
            matrixT[i, j] = Math.Sqrt(2 / (double)blok) * Math.Cos(((2 * j + 1) * i * Math.PI) / 2 * blok);
        }
    }

    return matrixT;

}

score 20 · Accepted Answer · answered Apr 07 '15 at 05:40

public double[,] Transpose(double[,] matrix)
{
    int w = matrix.GetLength(0);
    int h = matrix.GetLength(1);

    double[,] result = new double[h, w];

    for (int i = 0; i < w; i++)
    {
        for (int j = 0; j < h; j++)
        {
            result[j, i] = matrix[i, j];
        }
    }

    return result;
}

score 7 · Answer 2 · answered Oct 19 '16 at 13:11

public class Matrix<T>
{
    public static T[,] TransposeMatrix(T[,] matrix)
    {
        var rows    = matrix.GetLength(0);
        var columns = matrix.GetLength(1);

        var result = new T[columns, rows];

        for (var c = 0; c < columns; c++)
        {
            for (var r = 0; r < rows; r++)
            {
                result[c, r] = matrix[r, c];
            }
        }

        return result;
    }
}

And that is how to call it:

int[,] matris = new int[5, 8]
        {
            {1  , 2 , 3 , 4 , 5 , 6 , 7 , 8 },
            {9  , 10, 11, 12, 13, 14, 15, 16},
            {17 , 18, 19, 20, 21, 22, 23, 24},
            {25 , 26, 27, 28, 29, 30, 31, 32},
            {33 , 34, 35, 36, 37, 38, 39, 40},

        };
var tMatrix = Matrix<int>.TransposeMatrix(matris);

Mehmet TAŞ · Answer 3 · 2022-04-06T23:01:19.980

Your matrix is not a "perfect square" one. You need a result (transposedMatris) matrix. If your matrix were a perfect square one it would be enough to swap(a[i, j], a[j, i]) on the same matrix.

Generic type class has static method and the method should be called as below.

int[,] transposedMatris = Matrix.TransposeMatrix<int>(matris);
dumpMatrix(transposedMatris);

Dump the transposed matrix on console.

// Using Generics (dump string, integer, decimal, string)
public static void dumpMatrix<T>(T[,] a)
{
    int m = a.GetLength(0);
    int n = a.GetLength(1);
    for (int i = 0; i < m; i++)
    {
        for (int j = 0; j < n; j++)
        {
            Console.Write(a[i, j] + " ");
        }
        Console.WriteLine();
    }
    Console.WriteLine();
}

Transposed matrix dump:

1 9 17 25 33 
2 10 18 26 34 
3 11 19 27 35 
4 12 20 28 36 
5 13 21 29 37 
6 14 22 30 38 
7 15 23 31 39 
8 16 24 32 40

I am not süre but you need to rotate an image clockwise 90 degrees follow below steps.

Step 1: Transpose Matrix

Step 2: Flip horizontally

 int[,] a = new int[5, 5] {
     {1, 2, 3, 4, 5},
     {6, 7, 8, 9, 10},
     {11, 12, 13, 14, 15},
     {16, 17, 18, 19, 20},
     {21, 22, 23, 24, 25}
 };
 int m = a.GetLength(0);
 int n = a.GetLength(1);
 //dumpMatrix(a);

 // Step 1: Transpose Matrix
 int temp = 0;
 for (int i = 0; i < m; i++)
 {
     for (int j = i; j < n; j++)
     {
         temp = a[i, j];
         a[i, j] = a[j, i];
         a[j, i] = temp;
     }
 }
 //Console.WriteLine("Step 1: Transpose Matrix");
 //dumpMatrix(a);

 // Step 2: Flip horizontally
 for (int i = 0; i < m; i++)
 {
     for (int j = 0; j < (n/2); j++)
     {
         temp = a[i, j];
         a[i, j] = a[i, n - 1 - j];
         a[i, n - 1 - j] = temp;
     }
 }
 //Console.WriteLine("Step 2: Flip horizontally");
 //dumpMatrix(a);

How to transpose matrix?

3 Answers3

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