OpenCV 2.3 RC Python SVM: TypeError: <unknown> is not a numpy array

edit

Hello,

I am trying to use the new cv2 SVM (Support Vector Machine) Python binding in OpenCV 2.3 RC. I compiled OpenCV from source under Ubuntu 10.04 and as soon as I execute this function:

svm = cv2.SVM(training_data, responses)

I get the error:

TypeError: <unknown> is not a numpy array

Does anyone know what I am doing wrong or how to fix this?

Here is the full function I am using to train the SVM. The variables self.positive_samples and self.negative_samples are Python lists of SURF feature vectors (64 elements long). The variable self.classes is a Python list of 1's and -1's indicating the class a sample belongs to.

def init_classifier(self):

    n_positive_samples = len(self.positive_samples)
    n_negative_samples = len(self.negative_samples)

    n_samples = n_positive_samples + n_negative_samples

    training_data = cv.CreateMat(n_samples, 64, cv.CV_32FC1)
    responses = cv.CreateMat(n_samples, 1, cv.CV_32FC1)

    for i in range(n_positive_samples):
        cv.Set2D(responses, i, 0, self.classes[i])
        for j in range(64):        
            cv.Set2D(training_data, i, j, self.positive_samples[i][j])

    for i in range(n_positive_samples, n_samples):
        i_negative = i - n_positive_samples
        cv.Set2D(responses, i, 0, self.classes[i_negative])
        for j in range(64):        
            cv.Set2D(training_data, i, j, self.negative_samples[i_negative][j])

    svm = cv2.SVM(training_data, responses)