python struct文件读取mnist字节文件

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from PIL import Image
import struct

def read_image(filename):
    f = open(filename, 'rb')
    index = 0
    buf = f.read()
    f.close()
    magic, images, rows, columns = struct.unpack_from('>IIII' , buf , index)
    #print(magic, images, rows, columns)
    index += struct.calcsize('>IIII')

    for i in range(10):
        image = Image.new('L', (columns, rows))

        for x in range(rows):
            for y in range(columns):
                #print(struct.unpack_from('>B', buf, index))
                #print(repr(struct.unpack_from('>B', buf, index)))
                image.putpixel((y, x), int(struct.unpack_from('>B', buf, index)[0]))
                index += struct.calcsize('>B')
    print ('save ' + str(i) + 'image')
    image.save('E:\\study\\dataset\\t10k-labels-idx1-ubyte\\test' + str(i) + '.png')

def read_label(filename, saveFilename):
    f = open(filename, 'rb')
    index = 0
    buf = f.read()
    f.close()
    magic, labels = struct.unpack_from('>II' , buf , index)
    index += struct.calcsize('>II')
    labelArr = [0] * labels
    #labelArr = [0] * 2000
    for x in range(labels):
        #for x in xrange(2000):
        labelArr[x] = int(struct.unpack_from('>B', buf, index)[0])
        index += struct.calcsize('>B')
    save = open(saveFilename, 'w')
    save.write(','.join(map(lambda x: str(x), labelArr)))
    save.write('\n')
    save.close()
    print ('save labels success')

if __name__ == '__main__':
    read_image('E:\\study\\dataset\\t10k-images-idx3-ubyte\\t10k-images.idx3-ubyte')
    read_label('E:\\study\\dataset\\t10k-labels-idx1-ubyte\\t10k-labels.idx1-ubyte', 'E:\\study\\dataset\\t10k-labels-idx1-ubyte\\test\\label.txt')