Vfrdtyky

I'm using OpenCV kmeans alghoritm to compute some kind of histogram.

In the first stage, I'm taking some feautres extracted from my train data, and I'm putting it into one of cv::kmeans functions params.

The output of cv::kmeans gives me two different outputs.

• labels computed for my data


• centers, calcualted during executing cv::kmeans

In the next stage, I would like to compute labels for my test data, but using some data computed in the previous stage, but if I set KMEANS_USE_INITIAL_LABELS flag and pass labels computed in previous stage it produces an exception with message:

error: (-215:Assertion failed) (unsigned)_labels.at(i) < (unsigned)K in function 'kmeans'

Here is my wrapper method for cv::kmeans

void Kmeans::fit_predict(cv::InputArray in, cv::InputOutputArray out)

{

    // in is and input, my sample/s descriptors 

    // out -> computed labels; in first stage this array is empty



    int flag = cv::KMEANS_PP_CENTERS;



    if (!out.empty()) {

        flag = cv::KMEANS_USE_INITIAL_LABELS;



        cv::Mat m;



        out.copyTo(m);





        std::cout << m; // M has appropriate values, each value is < K(clusters amount) 



    } 



    cv::kmeans(in, _clusters_count, out, _term_criteria, _attempts, flag, _centers);



}

How I'm calling kmeans method(which is a part of my Kmeans class)

auto kmeans = std::make_unique<Kmeans>();



cv::Mat my_train_data .......initializing etc...

cv::Mat labels;



std::vector<Sample> test_samples ........initializng etc....





kmeans->fit_predict(my_train_data, labels);





for (auto& s : test_samples) {

   cv::Mat test_labels = labels.clone();



   kmeans->fit_predict(s->getDescriptors(), test_labels); 



   /// Process outputs etc...

}

Here are parameters with I'm calling cv::kmeans

• in -> defined above




• _clusters_count -> it is property of my class, it is 100




• out -> defined above




• _term_criteria -> stored as property of my class, it has value:
  cv::TermCriteria(cv::TermCriteria::MAX_ITER + cv::TermCriteria::EPS, 300, 0.0001)




• flag -> _attempts -> property of my class, it is 20




• _centers -> property of my class, it has default value: cv::noArray()

Why I'm getting this error?