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 use

Mat R(3, 4, CV_32F); // [3 rows x 4 cols] with float values
mat1.copyTo(R.row(0));
mat2.copyTo(R.row(1));
mat3.copyTo(R.row(2));

or

Mat R(4, 3, CV_32F); // [4 rows x 3 cols] with float values
mat1.copyTo(R.col(0));
mat2.copyTo(R.col(1));
mat3.copyTo(R.col(2));

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Alternatively, as @sub_o suggested, you can also use hconcat()/vconcat() to concatenate matrices.