Opencv C ++读取分配给特征向量的opencv Mat

Question

I have a matrix data = 8 rows x 1 cols declare in opencv. I want to read all the value and assign to Eigen Vector.

#include <opencv2/core.hpp>
#include <opencv2/opencv.hpp>
#include <vector>
#include <set>
#include <Eigen/Core>
#include <Eigen/Dense>
using namespace Eigen;

int main(int argc, char** argv)
{
Mat data;
int unique = data.rows;
VectorXd actualLabel(unique);
for(int i=0;i<unique;i++)
{
   for(int k = 0; k < train_label.cols; k++)
   {
       int val = train_label.at<double>(i, k);
       actualLabel(i) = val;
       cout<< actualLabel(i) << endl;
    }
}

return 0;
}

but the output is all 0 at Vector actualLable. How can i retrieve the actual value from Mat data?

Answer 1

I found the solution here would like to share the full program

#include <opencv2/core.hpp>
#include <opencv2/opencv.hpp>
#include <vector>
#include <set>
#include <Eigen/Core>
#include <Eigen/Dense>
using namespace Eigen;

int main(int argc, char** argv)
{
//example if data with assigned value 
Mat kern = (Mat_<double>(8, 1) << 0, -1, 0,-1, 5, -1,0, -1);
cout << kern << endl;
int unique = data.rows;
VectorXd actualLabel(unique);
for(int i=0;i<unique;i++)
{
   for(int k = 0; k < train_label.cols; k++)
   {
       double val = train_label.at<Vec2d>(i, k)[0];
       actualLabel(i) = val;
       cout<< actualLabel(i) << endl;
    }
}

return 0;
}

please comment if anything i can still improve here with shortest code. Thanks