mnist.py 文件源码

def _make_npz(path, urls):
    x_url, y_url = urls
    x_path = download.cached_download(x_url)
    y_path = download.cached_download(y_url)

    with gzip.open(x_path, 'rb') as fx, gzip.open(y_path, 'rb') as fy:
        fx.read(4)
        fy.read(4)
        N, = struct.unpack('>i', fx.read(4))
        if N != struct.unpack('>i', fy.read(4))[0]:
            raise RuntimeError('wrong pair of MNIST images and labels')
        fx.read(8)

        x = numpy.empty((N, 784), dtype=numpy.uint8)
        y = numpy.empty(N, dtype=numpy.uint8)

        for i in six.moves.range(N):
            y[i] = ord(fy.read(1))
            for j in six.moves.range(784):
                x[i, j] = ord(fx.read(1))

    numpy.savez_compressed(path, x=x, y=y)
    return {'x': x, 'y': y}