CvDTree train fails (C++)

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Hello everyone,

I have been trying to train a decision Tree for quite some time now but I always get an exception as soon as I try to train the tree. I really dont know what is going on and would appreciate any kind of help. I strongly oriented on the example found on this page (http://www.bytefish.de/blog/machine_l...) but I had to modify some things. Here is whats happening:

void decisiontree(cv::Mat& trainingData, cv::Mat& trainingClasses, cv::Mat& testData, cv::Mat& testClasses) {

CvDTree dtree;
//// this section doesnt work/////////
cv::Mat var_type(3, 1, CV_8U);

// define attributes as numerical
var_type.at<unsigned int>(0,0) = CV_VAR_NUMERICAL;
 var_type.at<unsigned int>(0,1) = CV_VAR_NUMERICAL;
// define output node as numerical
var_type.at<unsigned int>(0,2) = CV_VAR_NUMERICAL;
////////////////////////////
//instead:
cv::Mat vartype(3, 1, CV_8U, CV_VAR_NUMERICAL);

dtree.train(trainingData,CV_ROW_SAMPLE, trainingClasses, cv::Mat(), cv::Mat(), var_type, cv::Mat(), CvDTreeParams());//this call fails error message below
cv::Mat predicted(testClasses.rows, 1, CV_32F);
for (int i = 0; i < testData.rows; i++) {
    const cv::Mat sample = testData.row(i);
    CvDTreeNode* prediction = dtree.predict(sample);
    predicted.at<float> (i, 0) = prediction->value;
}

cout << "Accuracy_{TREE} = " << evaluate(predicted, testClasses) << endl;
plot_binary(testData, predicted, "Predictions tree");
}


int main() {

cv::Mat trainingData(numTrainingPoints, 2, CV_32FC1);
cv::Mat testData(numTestPoints, 2, CV_32FC1);

cv::randu(trainingData,0,1);
cv::randu(testData,0,1);

cv::Mat trainingClasses = labelData(trainingData, eq);
cv::Mat testClasses = labelData(testData, eq);

plot_binary(trainingData, trainingClasses, "Training Data");
plot_binary(testData, testClasses, "Test Data");

//These algorithms are working finde but are uncommented for the sake of simplicity
//svm(trainingData, trainingClasses, testData, testClasses); 
//mlp(trainingData, trainingClasses, testData, testClasses);
//knn(trainingData, trainingClasses, testData, testClasses, 3);
//bayes(trainingData, trainingClasses, testData, testClasses);
decisiontree(trainingData, trainingClasses, testData, testClasses);

cv::waitKey();

return 0;
}

First-chance exception at 0x000007FEFD65B3DD in xxx.exe: Microsoft C++ exception: cv::Exception at memory location 0x000000000012E510.

Falls ein Handler für diese Ausnahme vorhanden ist, kann das Programm möglicherweise weiterhin sicher ausgeführt werden.(If a handler exists for this excepition the programm can probably be exectued safely)

But if I continue I get: Unhandled exception at at 0x000007FEFD65B3DD in xxx.exe: Microsoft C++ exception: cv::Exception at memory location 0x000000000012E510.

Falls ein Handler für diese Ausnahme vorhanden ist, kann das Programm möglicherweise weiterhin sicher ausgeführt werden.

If I continue again I get the first exception and after a while I finally get:

Unbehandelte Ausnahme bei 0x000007FED279B207 (opencv_ml2410d.dll) in xxx.exe: 0xC0000005: Zugriffsverletzung beim Lesen an Position 0x0000000000000030

What is going on with the dll. Could there be any problem with that? I really dont kow how to fix this and would appreciate any help

Thank you