Function naive_bayes_train

examples/machine_learning/naive_bayes.cpp:25–50

}

void naive_bayes_train(float *priors, array &mu, array &sig2,
                       const array &train_feats, const array &train_classes,
                       int num_classes) {
    const int feat_len    = train_feats.dims(0);
    const int num_samples = train_classes.elements();

    // Get mean and variance from trianing data
    mu   = constant(0, feat_len, num_classes);
    sig2 = constant(0, feat_len, num_classes);

    for (int ii = 0; ii < num_classes; ii++) {
        array idx            = where(train_classes == ii);
        array train_feats_ii = lookup(train_feats, idx, 1);

        mu(span, ii) = mean(train_feats_ii, 1);

        // Some pixels are always 0. Add a small variance.
        sig2(span, ii) = var(train_feats_ii, AF_VARIANCE_SAMPLE, 1) + 0.01;

        // Calculate priors
        priors[ii] = (float)idx.elements() / (float)num_samples;
    }

    mu.eval();
    sig2.eval();
}

array naive_bayes_predict(float *priors, const array &mu, const array &sig2,
                          const array &test_feats, int num_classes) {