用python对minist数据集进行读取并保存成图片

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参考博客http://www.cnblogs.com/x1957/archive/2012/06/02/2531503.html，最近想要拿minist数据集练练手，想要将minsit数据集转换成图片格式，参考了上面博客后，有了下面这个demo，给大家分享下！好了，多的不说直接上代码！

#coding:utf-8
import numpy as np
import struct
import matplotlib.pyplot as plt
from scipy.misc import imsave

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

index = 0
#'>IIII'使用大端法读取四个unsigned int32
magic, numImages , numRows , numColumns = struct.unpack_from('>IIII' , buf , index)
index += struct.calcsize('>IIII')

# 输出大端数
print magic
print numImages
print numRows
print numColumns

for i in range(60000):
name = str(i) + ".jpg"
# upack_from从流中截取784位数据（图片像素值）
im = struct.unpack_from('>784B' ,buf, index)
index += struct.calcsize('>784B')

im = np.array(im)
im = im.reshape(28,28)
imsave(name, im)

# fig = plt.figure()
# plotwindow = fig.add_subplot(111)
# plt.imshow(im , cmap='gray')
# plt.show()

下面是读取label的demo，最后label会在label.txt文件夹中以列的形式存在。

#coding:utf-8
import numpy as np
import struct
# import matplotlib.pyplot as plt
# from scipy.misc import imsave

#filename = 'dat//train-images.idx3-ubyte'
filename =  'dat//train-labels.idx1-ubyte'
binfile = open(filename , 'rb')
buf = binfile.read()

f1 = open('label.txt', 'w')

index = 0
#'>IIII'使用大端法读取两个unsigned int32
magic, numLabels = struct.unpack_from('>II' , buf , index)
index += struct.calcsize('>II')

# 输出大端数
print magic
print numLabels

# for i in range(numLabels):
for i in range(numLabels):
numtemp = struct.unpack_from('1B' ,buf, index)
# numtemp 为tuple类型，读取其数值
num = numtemp[0]
# 存入label.txt文件中
f1.write(str(num))

f1.write('\n')
index += struct.calcsize('1B')
print num

# fig = plt.figure()
# plotwindow = fig.add_subplot(111)
# plt.imshow(im , cmap='gray')
# plt.show()

打完收工！demo下载地址：点击打开链接