opencv c++ mat转vector

数据类型float根据具体场景不同而不同，mat是已有的值

std::vector<std::vector<float>> vec;
for (int x = 0; x < mat.rows; x++) {
		for (int y = 0; y < mat.cols; y++) {
                vec[x][y] = mat.at<float>(x, y);
                 //std::cout << mat.at<float>(x, y) << std::endl;
         }
 }