python读取二进制mnist实例详解

training data 数据结构：

<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

将整个文件读入：

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

读取头四个32bit的interger:

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

读取一个图片，784=28*28 ：

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()

感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！