Question

There is a very simple way to construct a Mat from a vector…just by doing:

vector<int> myVector;
Mat myMatFromVector(myVector,true); //the boolean is to define if you want to copy the data

The problem with this contructor is that each vector’s element will be placed in each row of the Matrix. What I want is each element of my vector to be placed in each column of the matrix.

As is:
vector<int> = [1,2,3,4]
Matrix = [1;2;3;4]

I want:
vector<int> = [1,2,3,4]
Matrix = [1,2,3,4]

Answer 1

Either specify the shape and type of the Matrix and pass the vector data

   // constructor for matrix headers pointing to user-allocated data
    Mat(int _rows, int _cols, int _type, void* _data, size_t _step=AUTO_STEP);
    Mat(Size _size, int _type, void* _data, size_t _step=AUTO_STEP);

Or call reshape on the Mat to swap the number of row sand columns ( doesn’t change any data)

    // creates alternative matrix header for the same data, with different
    // number of channels and/or different number of rows. see cvReshape.
    Mat reshape(int _cn, int _rows=0) const;