mnist.py 文件源码

def _extract_labels(filename, num_classes=10):
        """???????????????

        :param filename: ?????
        :param num_classes: ??one-hot??????????10?
        :return: 2??numpy??[index, num_classes]? ???np.float32
        """
        labels = []
        print('Extracting {}'.format(filename))
        with gzip.GzipFile(fileobj=open(filename, 'rb')) as f:
            buf = f.read()
            index = 0
            magic, num_labels = struct.unpack_from('>II', buf, index)
            if magic != 2049:
                raise ValueError('Invalid magic number {} in MNIST label file: {}'.format(magic, filename))
            index += struct.calcsize('>II')
            for i in range(num_labels):
                label = struct.unpack_from('>B', buf, index)
                index += struct.calcsize('>B')
                label_one_hot = np.zeros(num_classes, dtype=np.float32)
                label_one_hot[label[0]] = 1
                labels.append(label_one_hot)
        return np.array(labels, dtype=np.float32)