Help loading and testing a trained svm [closed]

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I have been attempting to make an SVM for the dataset of handwritten digits that comes with openCV (samples/data/digits.png). I used the code from this source in order to train the svm, but I am having difficulty using the file it produces in java. When I try to use svm.predict(), it gives me this error:

"Assertion failed (samples.cols == var_count && samples.type() == 5) in cv::ml::SVMImpl::predict, file C:\build\master_winpack-bindings-win64-vc14-static\opencv\modules\ml\src\svm.cpp, line 2005"

I think this might have something to do with the format of my data, but I have no experience with this type of thing and could really use some help figuring it out. I am using Intelij 2017 community edition on windows 7 64 bit, with openCV 3.4.0. Here is my code:

private static double SZ = 20;
public static void main(String args[]) {
    SVM svm = SVM.load("C:\\Users\\User\\Desktop\\svm\\svm_data.dat");
    Mat image = Imgcodecs.imread("C:\\Users\\User\\Desktop\\svm\\1.jpg",Imgcodecs.IMREAD_GRAYSCALE);
    Core.bitwise_not(image,image); //makes the dark pencil lines white and the paper background black
    Imgproc.resize(image,image,new Size(20,20));
    Mat deskewed = deskew(image);

    HOGDescriptor hog = new HOGDescriptor(new Size(20,20),new Size(10,10), new Size(5,5), new Size(10,10),16,1,-1,0,0.2,true,64,true);

    MatOfFloat descriptors = new MatOfFloat();
    hog.compute(deskewed,descriptors);
    System.out.println(svm.predict(descriptors));
}

private static Mat deskew(Mat img) {
    Mat deskewed = new Mat();

    Moments m = Imgproc.moments(img);
    if(Math.abs(m.m02) < 1e-2) {
        return img.clone();
    }
    double skew = (float) m.mu11/m.mu02;
    Mat M = Mat.zeros(2,3, CvType.CV_32F);
    M.put(0,0, new float[] {1});
    M.put(0,1, new float[] {(float) skew});
    M.put(0,2, new float[] {(float) (-0.5*SZ*skew)});
    M.put(1,0, new float[] {0});
    M.put(1,1, new float[] {1});
    M.put(1,2, new float[] {0});
    System.out.println(M.dump());
    System.out.println(skew);
    Imgproc.warpAffine(img,deskewed,M,new Size(SZ,SZ),Imgproc.WARP_INVERSE_MAP | Imgproc.INTER_LINEAR);
    return deskewed;
}

and here is the image I am running the svm on: