python读取二进制mnist实例详解

<br>[offset] [type]     [value]     [description]0000   32 bit integer 0x00000803(2051) magic number0004   32 bit integer 60000      number of images0008   32 bit integer 28        number of rows0012   32 bit integer 28        number of columns0016   unsigned byte  ??        pixel0017   unsigned byte  ??        pixel........xxxx   unsigned byte  ??        pixel 

filename = 'train-images.idx3-ubyte'binfile = open(filename , 'rb')buf = binfile.read()

index = 0magic, numImages , numRows , numColumns = struct.unpack_from('>IIII' , buf , index)index += struct.calcsize('>IIII')

im = struct.unpack_from('>784B' ,buf, index)index += struct.calcsize('>784B') im = np.array(im)im = im.reshape(28,28) fig = plt.figure()plotwindow = fig.add_subplot(111)plt.imshow(im , cmap='gray')plt.show()