tensorflow 学习

在学习使用CNN对MNIST数据集进行识别的时候，遇到了一些问题，整理如下：

import numpy as np
import matplotlib.pyplot as plt
x = np.array([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,11,203,229,32,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,26,47,47,30,95,254,215,13,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,45,154,185,185,223,253,253,133,175,255,188,19,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,110,253,253,253,246,161,228,253,253,254,92,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,128,245,253,158,137,21,0,48,233,253,233,8,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,139,254,223,25,0,0,36,170,254,244,106,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,55,212,253,161,11,26,178,253,236,113,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7,155,253,228,80,223,253,253,109,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,141,253,253,253,254,253,154,29,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,110,253,253,253,254,179,38,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,171,254,254,254,179,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,171,253,253,253,253,178,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,26,123,254,253,203,156,253,200,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,93,253,254,121,13,93,253,158,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,64,239,253,76,8,32,219,253,126,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,133,254,191,0,5,108,234,254,106,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,132,253,190,5,85,253,236,154,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,153,253,169,192,253,253,77,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,112,253,253,254,236,129,9,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,118,243,191,113,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0])
image = x.reshape([28, 28])
cmap = 'gray_r'#加“_r”表示字体颜色和背景色互换
plt.imshow(image, cmap=plt.get_cmap(cmap))
plt.show()

这是数据集中的某一个数字，显示如下：

reshpae()是将原来的矩阵进行重新排列。

imshow()接收一张图像，只是画出该图，并不会立刻显示出来。

imshow后还可以进行其他draw操作，比如scatter散点等。

所有画完后使用plt.show()才能进行结果的显示。

cmap是colormap的简称，用于指定渐变色，默认的值为viridis, 在matplotlib中，内置了一系列的渐变色。get_cmap 后面的就是个名称，然后加 _r 表示反过来。

import numpy as np
import matplotlib.pyplot as plt
x = np.array([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,11,203,229,32,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,26,47,47,30,95,254,215,13,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,45,154,185,185,223,253,253,133,175,255,188,19,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,110,253,253,253,246,161,228,253,253,254,92,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,128,245,253,158,137,21,0,48,233,253,233,8,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,139,254,223,25,0,0,36,170,254,244,106,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,55,212,253,161,11,26,178,253,236,113,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7,155,253,228,80,223,253,253,109,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,141,253,253,253,254,253,154,29,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,110,253,253,253,254,179,38,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,171,254,254,254,179,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,171,253,253,253,253,178,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,26,123,254,253,203,156,253,200,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,93,253,254,121,13,93,253,158,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,64,239,253,76,8,32,219,253,126,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,133,254,191,0,5,108,234,254,106,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,132,253,190,5,85,253,236,154,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,153,253,169,192,253,253,77,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,112,253,253,254,236,129,9,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,118,243,191,113,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0])
image = x.reshape([28, 28])
cmap = 'gray'#这里是黑底白字
plt.imshow(image, cmap=plt.get_cmap(cmap))
plt.show()

 当然还可以换成其他颜色

import numpy as np
import matplotlib.pyplot as plt
x = np.array([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,11,203,229,32,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,26,47,47,30,95,254,215,13,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,45,154,185,185,223,253,253,133,175,255,188,19,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,110,253,253,253,246,161,228,253,253,254,92,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,128,245,253,158,137,21,0,48,233,253,233,8,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,139,254,223,25,0,0,36,170,254,244,106,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,55,212,253,161,11,26,178,253,236,113,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7,155,253,228,80,223,253,253,109,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,141,253,253,253,254,253,154,29,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,110,253,253,253,254,179,38,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,171,254,254,254,179,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,171,253,253,253,253,178,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,26,123,254,253,203,156,253,200,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,93,253,254,121,13,93,253,158,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,64,239,253,76,8,32,219,253,126,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,133,254,191,0,5,108,234,254,106,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,132,253,190,5,85,253,236,154,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,153,253,169,192,253,253,77,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,112,253,253,254,236,129,9,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,118,243,191,113,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0])
image = x.reshape([28, 28])
cmap = 'Purples'
plt.imshow(image, cmap=plt.get_cmap(cmap))
plt.show()