utils.py 文件源码

def iter_combinatorial_pairs(queue, num_examples, batch_size, interval,
                             num_classes, augment_positive=False):
    num_examples_per_class = num_examples // num_classes
    pairs = np.array(list(itertools.combinations(range(num_examples), 2)))

    if augment_positive:
        additional_positive_pairs = make_positive_pairs(
             num_classes, num_examples_per_class, num_classes - 1)
        pairs = np.concatenate((pairs, additional_positive_pairs))

    num_pairs = len(pairs)
    num_batches = num_pairs // batch_size
    perm = np.random.permutation(num_pairs)
    for i, batch_indexes in enumerate(np.array_split(perm, num_batches)):
        if i % interval == 0:
            x, c = queue.get()
            x = x.astype(np.float32) / 255.0
            c = c.ravel()
        indexes0, indexes1 = pairs[batch_indexes].T
        x0, x1, c0, c1 = x[indexes0], x[indexes1], c[indexes0], c[indexes1]
        t = np.int32(c0 == c1)  # 1 if x0 and x1 are same class, 0 otherwise
        yield x0, x1, t