SVM model training and classification return error

System Information

OpenCV version: 4.10.0
Operating System:win10
Compiler & compiler version: VS2022

Detailed description

An exception was raised: read access permission conflict.
SVM. * * Ptr * * is nullptr.

Steps to reproduce

#include <stdio.h>  
#include <time.h>  
#include <opencv2/opencv.hpp>   
#include <iostream> 
#include <opencv2/core/core.hpp>  
#include <opencv2/highgui/highgui.hpp>  
#include <opencv2/ml/ml.hpp>  
#include <io.h>
#include <vector>  
#include <string> 
#include <filesystem>  

using namespace std;
using namespace cv;
namespace fs = std::filesystem;

void getFiles(std::string& path, vector<string>& files) {
	for (const auto& entry : fs::directory_iterator(path)) {
		  
		if (entry.is_regular_file()) {
			files.push_back(entry.path().string());
		}
	}
}

int main()
{
	int result = 0;
	string filePath = "D:\\vcworkspace\\digits_svm\\digits_svm\\data\\test_image\\0";
	vector<string> files;
	getFiles(filePath, files);
	int number = files.size();
	cout << number << endl;
	Ptr<ml::SVM> svm;
	
	string modelpath = "digits_svm.yml";
	vector<float> predictions;
	FileStorage svm_fs(modelpath, FileStorage::READ);
	if (svm_fs.isOpened())
	{
		svm->load(modelpath.c_str());
	}
	for (int i = 0; i < number; i++)
	{
		Mat inMat = imread(files[i].c_str());
		Mat p = inMat.reshape(1, 1);
		p.convertTo(p, CV_32FC1);
		int response = (int)svm->predict(p);
		if (response == 0)
		{
			result++;
		}
	}
	cout << result << endl;
	getchar();
	return  0;
}

All the projects are here.

https://github.com/ZJDATY/digits_svm/tree/master

Issue submission checklist

I report the issue, it's not a question
I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
I updated to the latest OpenCV version and the issue is still there
There is reproducer code and related data files (videos, images, onnx, etc)

Hello. if you have "question", please could you ask at QA forum ? https://forum.opencv.org/

In your code, return value of load function is not used. Please could you confirm how to use ?

https://docs.opencv.org/4.10.0/d1/d2d/classcv_1_1ml_1_1SVM.html#af82a9714aecd48d61d88f0ce6f6035ed

This is sample code to load SVM model. model is Ptr<StatModel>, which is super class of Ptr<SVM>.

opencv/modules/ml/test/test_save_load.cpp

Lines 63 to 64 in 71d3237

    
           else if (modelName == CV_SVM) 
        
               model = Algorithm::load<SVM>(filename);

So I believe your code should be updated with following.

- svm->load(modelpath.c_str());
+ svm = SVM::load(modelpath.c_str());

(because svm is not created, it is better to not calling svm->load())

Hello. if you have "question", please could you ask at QA forum ? https://forum.opencv.org/

In your code, return value of load function is not used. Please could you confirm how to use ?

https://docs.opencv.org/4.10.0/d1/d2d/classcv_1_1ml_1_1SVM.html#af82a9714aecd48d61d88f0ce6f6035ed

This is sample code to load SVM model. is , which is super class of .model``Ptr<StatModel>``Ptr<SVM>

opencv/modules/ml/test/test_save_load.cpp

Lines 63 to 64 in 71d3237

else if (modelName == CV_SVM)

model = Algorithm::load<SVM>(filename);

So I believe your code should be updated with following.
- svm->load(modelpath.c_str());
+ svm = SVM::load(modelpath.c_str());
(because is not created, it is better to not calling svm``svm->load())

thank you

	else if (modelName == CV_SVM)
	model = Algorithm::load<SVM>(filename);