How to merge 3 matrices into 1 in opencv?

Question

I have three matrices, each of size 4x1. I want to copy all of these matrices to another matrix of size 4x3 and call it R. Is there a

Answer 1

You can just use hconcat for horizontal concatenation. You can use it per matrix, e.g. hconcat( mat1, mat2, R ), or apply it directly on a vector or array of matrices.

Here's a sample code:

vector matrices = {
    Mat(4, 1, CV_8UC1, Scalar(1)),
    Mat(4, 1, CV_8UC1, Scalar(2)),
    Mat(4, 1, CV_8UC1, Scalar(3)),
};
Mat R;
hconcat( matrices, R );
cout << R << endl;

Here's the result:

[1, 2, 3;
  1, 2, 3;
  1, 2, 3;
  1, 2, 3]
Program ended with exit code: 1

Similarly, if you want to do it vertically (stack by rows), use vconcat.