TensorFlow

一、TensorFlow介绍

1、什么是TensorFlow

官网：https://www.tensorflow.org/
TensorFlow是Google开发的一款神经网络的Python外部的结构包, 也是一个采用数据流图来进行数值计算的开源软件库.
先绘制计算结构图, 也可以称是一系列可人机交互的计算操作, 然后把编辑好的Python文件转换成更高效的C++, 并在后端进行计算.

2、TensorFlow强大之处

擅长的任务就是训练深度神经网络
快速的入门神经网络,大大降低了深度学习（也就是深度神经网络）的开发成本和开发难度
TensorFlow 的开源性, 让所有人都能使用并且维护

3、安装TensorFlow

暂不支持Windows下安装TensorFlow,可以在虚拟机里使用或者安装Docker安装
这里在CentOS6.5下进行安装
安装Python2.7，默认CentOS中安装的是Python2.6
先安装zlib的依赖，下面安装easy_install时会用到

yum install zlib
yum install zlib-devel

在安装openssl的依赖，下面安装pip时会用到

yum install openssl
yum install openssl-devel

下载安装包，我传到github上的安装包，https协议后面加上--no-check-certificate，：

   wget https://raw.githubusercontent.com/lawlite19/LinuxSoftware/master/python/Python-2.7.12.tgz --no-check-certificate

解压缩：tar -zxvf xxx
进入，配置：./configure --prefix=/usr/local/python2.7
编译并安装：make && make install
创建链接来使系统默认python变为python2.7, ln -fs /usr/local/python2.7/bin/python2.7 /usr/bin/python
修改一下yum，因为yum的执行文件还是需要原来的python2.6,vim /usr/bin/yum

#!/usr/bin/python

修改为系统原有的python版本地址

#!/usr/bin/python2.6

安装easy_install
下载：wget https://raw.githubusercontent.com/lawlite19/LinuxSoftware/blob/master/python/setuptools-26.1.1.tar.gz --no-check-certificate
解压缩：tar -zxvf xxx
python setup.py build #注意这里python是新的python2.7
python setup.py install
到/usr/local/python2.7/bin目录下查看就会看到easy_install了
创建一个软连接：ln -s /usr/local/python2.7/bin/easy_install /usr/local/bin/easy_install
就可以使用easy_install 包名 进行安装
安装pip
下载:
解压缩：tar -zxvf xxx
安装：python setup.py install
到/usr/local/python2.7/bin目录下查看就会看到pip了
同样创建软连接：ln -s /usr/local/python2.7/bin/pip /usr/local/bin/pip
就可以使用pip install 包名进行安装包了
安装wingIDE
默认安装到/usr/local/lib下，进入，执行./wing命令即可执行
创建软连接：ln -s /usr/local/lib/wingide5.1/wing /usr/local/bin/wing
破解：
[另]安装VMwareTools，可以在windows和Linux之间复制粘贴
启动CentOS
选择VMware中的虚拟机-->安装VMware Tools
会自动弹出VMware Tools的文件夹
拷贝一份到root目录下 cp VMwareTools-9.9.3-2759765.tar.gz /root
解压缩 tar -zxvf VMwareTools-9.9.3-2759765.tar.gz
进入目录执行，vmware-install.pl，一路回车下去即可
重启CentOS即可
安装numpy
直接安装没有出错
安装scipy
安装依赖：yum install bzip2-devel pcre-devel ncurses-devel readline-devel tk-devel gcc-c++ lapack-devel
安装即可：pip install scipy
安装matplotlib
安装依赖：yum install libpng-devel
安装即可：pip install matplotlib
运行可能有以下的错误：

   ImportError: No module named _tkinter

安装：tcl8.5.9-src.tar.gz

进入安装即可,./confgiure make make install 安装：tk8.5.9-src.tar.gz
进入安装即可。
[注意]要重新安装一下Pyhton2.7才能链接到tkinter
安装scikit-learn
直接安装没有出错，但是缺少包bz2
将系统中python2.6的bz2复制到python2.7对应文件夹下

cp /usr/lib/python2.6/lib-dynload/bz2.so /usr/local/python2.7/lib/python2.7/lib-dynload

安装TensorFlow
官网点击
选择对应的版本

    # Ubuntu/Linux 64-bit, CPU only, Python 2.7
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/linux/cpu/tensorflow-0.12.0rc0-cp27-none-linux_x86_64.whl
   
   # Ubuntu/Linux 64-bit, GPU enabled, Python 2.7
   # Requires CUDA toolkit 8.0 and CuDNN v5. For other versions, see "Installing from sources" below.
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/linux/gpu/tensorflow_gpu-0.12.0rc0-cp27-none-linux_x86_64.whl
   
   # Mac OS X, CPU only, Python 2.7:
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-0.12.0rc0-py2-none-any.whl
   
   # Mac OS X, GPU enabled, Python 2.7:
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/mac/gpu/tensorflow_gpu-0.12.0rc0-py2-none-any.whl
   
   # Ubuntu/Linux 64-bit, CPU only, Python 3.4
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/linux/cpu/tensorflow-0.12.0rc0-cp34-cp34m-linux_x86_64.whl
   
   # Ubuntu/Linux 64-bit, GPU enabled, Python 3.4
   # Requires CUDA toolkit 8.0 and CuDNN v5. For other versions, see "Installing from sources" below.
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/linux/gpu/tensorflow_gpu-0.12.0rc0-cp34-cp34m-linux_x86_64.whl
   
   # Ubuntu/Linux 64-bit, CPU only, Python 3.5
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/linux/cpu/tensorflow-0.12.0rc0-cp35-cp35m-linux_x86_64.whl
   
   # Ubuntu/Linux 64-bit, GPU enabled, Python 3.5
   # Requires CUDA toolkit 8.0 and CuDNN v5. For other versions, see "Installing from sources" below.
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/linux/gpu/tensorflow_gpu-0.12.0rc0-cp35-cp35m-linux_x86_64.whl
   
   # Mac OS X, CPU only, Python 3.4 or 3.5:
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-0.12.0rc0-py3-none-any.whl
   
   # Mac OS X, GPU enabled, Python 3.4 or 3.5:
   $ export TF_BINARY_URL=https://storage.googleapis.com/tensorflow/mac/gpu/tensorflow_gpu-0.12.0rc0-py3-none-any.whl

对应python版本

    # Python 2
   $ sudo pip install --upgrade $TF_BINARY_URL
   
   # Python 3
   $ sudo pip3 install --upgrade $TF_BINARY_URL

可能缺少依赖glibc,看对应提示的版本，
还有可能报错

ImportError: /usr/lib64/libstdc++.so.6: version `GLIBCXX_3.4.19' not found (required by /usr/local/python2.7/lib/python2.7/site-packages/tensorflow/python/_pywrap_tensorflow.so)

安装对应版本的glibc
查看现有版本的glibc, strings /lib64/libc.so.6 |grep GLIBC
下载对应版本：wget http://ftp.gnu.org/gnu/glibc/glibc-2.17.tar.gz
解压缩：tar -zxvf glibc-2.17
进入文件夹创建build文件夹cd glibc-2.17 && mkdir build
配置：

../configure  \
   --prefix=/usr          \
   --disable-profile      \
   --enable-add-ons       \
   --enable-kernel=2.6.25 \
   --libexecdir=/usr/lib/glibc

编译安装：make && make install
可以再用命令：strings /lib64/libc.so.6 |grep GLIBC查看
添加GLIBCXX_3.4.19的支持
下载：wget https://raw.githubusercontent.com/lawlite19/LinuxSoftware/master/python2.7_tensorflow/libstdc++.so.6.0.20
复制到/usr/lib64文件夹下：cp libstdc++.so.6.0.20 /usr/lib64/
添加执行权限：chmod +x /usr/lib64/libstdc++.so.6.0.20
删除原来的：rm -rf /usr/lib64/libstdc++.so.6
创建软连接：ln -s /usr/lib64/libstdc++.so.6.0.20 /usr/lib64/libstdc++.so.6
可以查看是否有个版本：strings /usr/lib64/libstdc++.so.6 | grep GLIBCXX
运行还可能报错编码的问题，这里安装0.10.0版本:pip install --upgrade https://storage.googleapis.com/tensorflow/linux/cpu/tensorflow-0.10.0rc0-cp27-none-linux_x86_64.whl
安装pandas
pip install pandas没有问题

二、TensorFlow基础架构

1、处理结构

Tensorflow 首先要定义神经网络的结构,然后再把数据放入结构当中去运算和 training
TensorFlow是采用数据流图（data　flow　graphs）来计算
首先我们得创建一个数据流流图
然后再将我们的数据（数据以张量(tensor)的形式存在）放在数据流图中计算
张量（tensor):
张量有多种. 零阶张量为纯量或标量 (scalar) 也就是一个数值. 比如 1
一阶张量为向量 (vector), 比如一维的 [1, 2, 3]
二阶张量为矩阵 (matrix), 比如二维的 [[1, 2, 3],[4, 5, 6],[7, 8, 9]]
以此类推, 还有三阶三维的 …

2、一个例子

求y=1*x+3中的权重1和偏置3
定义这个函数

   x_data = np.random.rand(100).astype(np.float32)
   y_data = x_data*1.0+3.0

创建TensorFlow结构

   Weights = tf.Variable(tf.random_uniform([1], -1.0, 1.0)) # 创建变量Weight是，范围是 -1.0~1.0
   biases = tf.Variable(tf.zeros([1]))                      # 创建偏置，初始值为0
   y = Weights*x_data+biases                                # 定义方程
   loss = tf.reduce_mean(tf.square(y-y_data))               # 定义损失，为真实值减去我们每一步计算的值
   optimizer = tf.train.GradientDescentOptimizer(0.5)       # 0.5 是学习率
   train = optimizer.minimize(loss)                         # 使用梯度下降优化
   init = tf.initialize_all_variables()                     # 初始化所有变量

定义Session

   sess = tf.Session()
   sess.run(init)

输出结果

for i in range(201):
   sess.run(train)
   if i%20 == 0:
       print i,sess.run(Weights),sess.run(biases)

结果为：

0 [ 1.60895896] [ 3.67376709]
20 [ 1.04673827] [ 2.97489643]
40 [ 1.011392] [ 2.99388123]
60 [ 1.00277638] [ 2.99850869]
80 [ 1.00067675] [ 2.99963641]
100 [ 1.00016499] [ 2.99991131]
120 [ 1.00004005] [ 2.99997854]
140 [ 1.00000978] [ 2.99999475]
160 [ 1.0000025] [ 2.99999857]
180 [ 1.00000119] [ 2.99999928]
200 [ 1.00000119] [ 2.99999928]

3、Session会话控制

运行 session.run() 可以获得你要得知的运算结果, 或者是你所要运算的部分
定义常量矩阵：tf.constant([[3,3]])
矩阵乘法：tf.matmul(matrix1,matrix2)
运行Session的两种方法：
手动关闭

   sess = tf.Session()
   print sess.run(product)
   sess.close()

使用with，执行完会自动关闭

   with tf.Session() as sess:
   print sess.run(product)

4、`Variable`变量

定义变量：tf.Variable()
初始化所有变量：init = tf.initialize_all_variables()
需要再在 sess 里, sess.run(init) , 激活变量
输出时，一定要把 sess 的指针指向变量再进行 print 才能得到想要的结果

5、`Placeholder`传入值

首先定义Placeholder，然后在Session.run()的时候输入值
placeholder 与 feed_dict={} 是绑定在一起出现的

input1 = tf.placeholder(tf.float32) #在 Tensorflow 中需要定义 placeholder 的 type ，一般为 float32 形式
input2 = tf.placeholder(tf.float32)

output = tf.mul(input1,input2)  # 乘法运算

with tf.Session() as sess:
    print sess.run(output,feed_dict={input1:7.,input2:2.}) # placeholder 与 feed_dict={} 是绑定在一起出现的

三、定义一个神经网络

1、添加层函数`add_layer()`

'''参数：输入数据，前一层size，当前层size，激活函数'''
def add_layer(inputs,in_size,out_size,activation_function=None):
    Weights = tf.Variable(tf.random_normal([in_size,out_size]))  #随机初始化权重
    biases = tf.Variable(tf.zeros([1,out_size]) + 0.1)  # 初始化偏置，+0.1
    Ws_plus_b = tf.matmul(inputs,Weights) + biases      # 未使用激活函数的值
    if activation_function is None:
        outputs = Ws_plus_b
    else:
        outputs = activation_function(Ws_plus_b)   # 使用激活函数激活
    return outputs

2、构建神经网络

定义二次函数

x_data = np.linspace(-1,1,300,dtype=np.float32)[:,np.newaxis]
noise = np.random.normal(0,0.05,x_data.shape).astype(np.float32)
y_data = np.square(x_data)-0.5+noise

定义Placeholder,用于后期输入数据

xs = tf.placeholder(tf.float32,[None,1]) # None代表无论输入有多少都可以,只有一个特征，所以这里是1
ys = tf.placeholder(tf.float32,[None,1])

定义神经层layer

layer1 = add_layer(xs, 1, 10, activation_function=tf.nn.relu) # 第一层，输入层为1，隐含层为10个神经元，Tensorflow 自带的激励函数tf.nn.relu

定义输出层

prediction = add_layer(layer1, 10, 1) # 利用上一层作为输入

计算loss损失

loss = tf.reduce_mean(tf.reduce_sum(tf.square(ys-prediction),reduction_indices=[1])) # 对二者差的平方求和再取平均

梯度下降最小化损失

train = tf.train.GradientDescentOptimizer(0.1).minimize(loss)

初始化所有变量

init = tf.initialize_all_variables()

定义Session

sess = tf.Session()
sess.run(init)

输出

for i in range(1000):
    sess.run(train,feed_dict={xs:x_data,ys:y_data})
    if i%50==0:
        print sess.run(loss,feed_dict={xs:x_data,ys:y_data})

结果：

3、可视化结果

显示数据

    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.scatter(x_data,y_data)
    plt.ion()   # 绘画之后不暂停
    plt.show()

动态绘画

        try:
            ax.lines.remove(lines[0])   # 每次绘画需要移除上次绘画的结果，放在try catch里因为第一次执行没有，所以直接pass
        except Exception:
            pass
        prediction_value = sess.run(prediction, feed_dict={xs: x_data})
        # plot the prediction
        lines = ax.plot(x_data, prediction_value, 'r-', lw=3)  # 绘画
        plt.pause(0.1)  # 停0.1s

四、TensorFlow可视化

1、TensorFlow的可视化工具`tensorboard`，可视化神经网路额结构

输入input

with tf.name_scope('input'):
    xs = tf.placeholder(tf.float32,[None,1],name='x_in')  # 
    ys = tf.placeholder(tf.float32,[None,1],name='y_in')

layer层

def add_layer(inputs,in_size,out_size,activation_function=None):
    with tf.name_scope('layer'):
        with tf.name_scope('Weights'):
            Weights = tf.Variable(tf.random_normal([in_size,out_size]),name='W')
        with tf.name_scope('biases'):
            biases = tf.Variable(tf.zeros([1,out_size]) + 0.1,name='b')
        with tf.name_scope('Ws_plus_b'):
            Ws_plus_b = tf.matmul(inputs,Weights) + biases
        if activation_function is None:                                       outputs = Ws_plus_b
        else:                                                            
            outputs = activation_function(Ws_plus_b)  
        return outputs

loss和train

with tf.name_scope('loss'):
    loss = tf.reduce_mean(tf.reduce_sum(tf.square(ys-prediction),reduction_indices=[1]))

with tf.name_scope('train'):
    train = tf.train.GradientDescentOptimizer(0.1).minimize(loss)

写入文件中

writer = tf.train.SummaryWriter("logs/", sess.graph)

浏览器中查看（chrome浏览器）
在终端输入：tensorboard --logdir='logs/'，它会给出访问地址
浏览器中查看即可。
tensorboard命令在安装python目录的bin目录下，可以创建一个软连接

2、可视化训练过程

可视化Weights权重和biases偏置
每一层起个名字

layer_name = 'layer%s'%n_layer

tf.histogram_summary(name,value)

def add_layer(inputs,in_size,out_size,n_layer,activation_function=None):
   layer_name = 'layer%s'%n_layer
   with tf.name_scope(layer_name):
       with tf.name_scope('Weights'):
           Weights = tf.Variable(tf.random_normal([in_size,out_size]),name='W')
           tf.histogram_summary(layer_name+'/weights', Weights)
       with tf.name_scope('biases'):
           biases = tf.Variable(tf.zeros([1,out_size]) + 0.1,name='b')
           tf.histogram_summary(layer_name+'/biases',biases)
       with tf.name_scope('Ws_plus_b'):
           Ws_plus_b = tf.matmul(inputs,Weights) + biases
                                     
       if activation_function is None:             
           outputs = Ws_plus_b 
       else:                                                         
           outputs = activation_function(Ws_plus_b)      
       tf.histogram_summary(layer_name+'/outputs',outputs)
       return outputs

merge所有的summary

merged =tf.merge_all_summaries()

写入文件中

writer = tf.train.SummaryWriter("logs/", sess.graph)

训练1000次，每50步显示一次：

for i in range(1000):
   sess.run(train,feed_dict={xs:x_data,ys:y_data})
   if i%50==0:
       summary = sess.run(merged, feed_dict={xs: x_data, ys:y_data})
       writer.add_summary(summary, i)

同样适用tensorboard查看
可视化损失函数（代价函数）
添加：tf.scalar_summary('loss',loss)

五、手写数字识别_1

1、说明

全部代码：https://github.com/lawlite19/MachineLearning_TensorFlow/blob/master/Mnist_02/mnist.py
自己的数据集，没有使用tensorflow中mnist数据集，
之前在机器学习中用Python实现过，地址：https://github.com/lawlite19/MachineLearning_Python,这里使用tensorflow实现
神经网络只有两层

2、代码实现

添加一层

'''添加一层神经网络'''
def add_layer(inputs,in_size,out_size,activation_function=None):
    Weights = tf.Variable(tf.random_normal([in_size,out_size]))    # 权重，in*out 
    biases = tf.Variable(tf.zeros([1,out_size]) + 0.1)  
    Ws_plus_b = tf.matmul(inputs,Weights) + biases   # 计算权重和偏置之后的值                         
    if activation_function is None:                                     
        outputs = Ws_plus_b                                               
    else:                                                         
        outputs = activation_function(Ws_plus_b)    # 调用激励函数运算    
    return outputs

运行函数

'''运行函数'''
def NeuralNetwork():
    data_digits = spio.loadmat('data_digits.mat')
    X = data_digits['X']
    y = data_digits['y']
    m,n = X.shape
    class_y = np.zeros((m,10))      # y是0,1,2,3...9,需要映射0/1形式
    for i in range(10):
        class_y[:,i] = np.float32(y==i).reshape(1,-1) 
    
    xs = tf.placeholder(tf.float32, shape=[None,400])  # 像素是20x20=400，所以有400个feature
    ys = tf.placeholder(tf.float32, shape=[None,10])   # 输出有10个
    
    prediction = add_layer(xs, 400, 10, activation_function=tf.nn.softmax) # 两层神经网络，400x10
    #prediction = add_layer(layer1, 25, 10, activation_function=tf.nn.softmax)
 
    #loss = tf.reduce_mean(tf.reduce_sum(tf.square(ys-prediction),reduction_indices=[1]))
    loss = tf.reduce_mean(-tf.reduce_sum(ys*tf.log(prediction),reduction_indices=[1]))  # 定义损失函数（代价函数），
    train = tf.train.GradientDescentOptimizer(learning_rate=0.5).minimize(loss)     # 使用梯度下降最小化损失
    init = tf.initialize_all_variables()   # 初始化所有变量
    
    sess = tf.Session()  # 创建Session
    sess.run(init)
    
    for i in range(4000): # 迭代训练4000次
        sess.run(train, feed_dict={xs:X,ys:class_y})  # 训练train，填入数据
        if i%50==0:  # 每50次输出当前的准确度
            print(compute_accuracy(xs,ys,X,class_y,sess,prediction))

计算准确度

'''计算预测准确度'''  
def compute_accuracy(xs,ys,X,y,sess,prediction):
    y_pre = sess.run(prediction,feed_dict={xs:X}) 
    correct_prediction = tf.equal(tf.argmax(y_pre,1),tf.argmax(y,1))  #tf.argmax 给出某个tensor对象在某一维上的其数据最大值所在的索引值,即为对应的数字，tf.equal 来检测我们的预测是否真实标签匹配
    accuracy = tf.reduce_mean(tf.cast(correct_prediction,tf.float32)) # 平均值即为准确度
    result = sess.run(accuracy,feed_dict={xs:X,ys:y})
    return result

输出每一次预测的结果准确度

六、手写数字识别_2

1、说明

全部代码：https://github.com/lawlite19/MachineLearning_TensorFlow/blob/master/Mnist_02/mnist.py
采用TensorFlow中的mnist数据集（可以取网站下载它的数据集，http://yann.lecun.com/exdb/mnist/）
实现代码与上面类似，它有专门的测试集

2、代码

随机梯度下降SGD,每次选出100个数据进行训练

for i in range(2000):
        batch_xs, batch_ys = minist.train.next_batch(100)
        sess.run(train_step,feed_dict={xs:batch_xs,ys:batch_ys})
        if i%50==0:
            print(compute_accuracy(xs,ys,minist.test.images, minist.test.labels,sess,prediction))

输出每一次预测的结果准确度

七、手写数字识别_3_CNN卷积神经网络

1、说明

关于卷积神经网络CNN可以查看我的博客：http://blog.csdn.net/u013082989/article/details/53673602
或者github：https://github.com/lawlite19/DeepLearning_Python
全部代码：https://github.com/lawlite19/MachineLearning_TensorFlow/blob/master/Mnist_03_CNN/mnist_cnn.py
采用TensorFlow中的mnist数据集（可以取网站下载它的数据集，http://yann.lecun.com/exdb/mnist/）

2、代码实现

权重和偏置初始化函数
权重使用的truncated_normal进行初始化,stddev标准差定义为0.1
偏置初始化为常量0.1

'''权重初始化函数'''
def weight_variable(shape):
    inital = tf.truncated_normal(shape, stddev=0.1)  # 使用truncated_normal进行初始化
    return tf.Variable(inital)

'''偏置初始化函数'''
def bias_variable(shape):
    inital = tf.constant(0.1,shape=shape)  # 偏置定义为常量
    return tf.Variable(inital)

卷积函数
strides[0]和strides[3]的两个1是默认值，中间两个1代表padding时在x方向运动1步，y方向运动1步
padding='SAME'代表经过卷积之后的输出图像和原图像大小一样

'''卷积函数'''
def conv2d(x,W):#x是图片的所有参数，W是此卷积层的权重
    return tf.nn.conv2d(x,W,strides=[1,1,1,1],padding='SAME')#strides[0]和strides[3]的两个1是默认值，中间两个1代表padding时在x方向运动1步，y方向运动1步

池化函数
ksize指定池化核函数的大小
根据池化核函数的大小定义strides的大小

'''池化函数'''
def max_pool_2x2(x):
    return tf.nn.max_pool(x,ksize=[1,2,2,1],
                          strides=[1,2,2,1],                          padding='SAME')#池化的核函数大小为2x2，因此ksize=[1,2,2,1]，步长为2，因此strides=[1,2,2,1]

加载mnist数据和定义placeholder
输入数据x_image最后一个1代表channel的数量,若是RGB3个颜色通道就定义为3
keep_prob 用于dropout防止过拟合

    mnist = input_data.read_data_sets('MNIST_data', one_hot=True)  # 下载数据
    
    xs = tf.placeholder(tf.float32,[None,784])  # 输入图片的大小，28x28=784
    ys = tf.placeholder(tf.float32,[None,10])   # 输出0-9共10个数字
    keep_prob = tf.placeholder(tf.float32)      # 用于接收dropout操作的值，dropout为了防止过拟合
    x_image = tf.reshape(xs,[-1,28,28,1])       #-1代表先不考虑输入的图片例子多少这个维度，后面的1是channel的数量，因为我们输入的图片是黑白的，因此channel是1，例如如果是RGB图像，那么channel就是3

第一层卷积和池化
- 使用ReLu激活函数

    '''第一层卷积，池化'''
    W_conv1 = weight_variable([5,5,1,32])  # 卷积核定义为5x5,1是输入的通道数目，32是输出的通道数目
    b_conv1 = bias_variable([32])          # 每个输出通道对应一个偏置
    h_conv1 = tf.nn.relu(conv2d(x_image,W_conv1)+b_conv1) # 卷积运算，并使用ReLu激活函数激活
    h_pool1 = max_pool_2x2(h_conv1)        # pooling操作

第二层卷积和池化

    '''第二层卷积，池化'''
    W_conv2 = weight_variable([5,5,32,64]) # 卷积核还是5x5,32个输入通道，64个输出通道
    b_conv2 = bias_variable([64])          # 与输出通道一致
    h_conv2 = tf.nn.relu(conv2d(h_pool1, W_conv2)+b_conv2)
    h_pool2 = max_pool_2x2(h_conv2)

全连接第一层

    '''全连接层'''
    h_pool2_flat = tf.reshape(h_pool2, [-1,7*7*64])   # 将最后操作的数据展开
    W_fc1 = weight_variable([7*7*64,1024])            # 下面就是定义一般神经网络的操作了，继续扩大为1024
    b_fc1 = bias_variable([1024])                     # 对应的偏置
    h_fc1 = tf.nn.relu(tf.matmul(h_pool2_flat,W_fc1)+b_fc1)  # 运算、激活（这里不是卷积运算了，就是对应相乘）

dropout防止过拟合

    '''dropout'''
    h_fc1_drop = tf.nn.dropout(h_fc1,keep_prob)       # dropout操作

最后一层全连接预测,使用梯度下降优化交叉熵损失函数
使用softmax分类器分类

    '''最后一层全连接'''
    W_fc2 = weight_variable([1024,10])                # 最后一层权重初始化
    b_fc2 = bias_variable([10])                       # 对应偏置
    
    prediction = tf.nn.softmax(tf.matmul(h_fc1_drop,W_fc2)+b_fc2)  # 使用softmax分类器
    cross_entropy = tf.reduce_mean(-tf.reduce_sum(ys*tf.log(prediction),reduction_indices=[1]))  # 交叉熵损失函数来定义cost function
    train_step = tf.train.AdamOptimizer(1e-3).minimize(cross_entropy)  # 调用梯度下降

定义Session，使用SGD训练

    '''下面就是tf的一般操作，定义Session，初始化所有变量，placeholder传入值训练'''
    sess = tf.Session()
    sess.run(tf.initialize_all_variables())
    
    for i in range(1000):
        batch_xs, batch_ys = mnist.train.next_batch(100)  # 使用SGD，每次选取100个数据训练
        sess.run(train_step, feed_dict={xs: batch_xs, ys: batch_ys, keep_prob: 0.5})  # dropout值定义为0.5
        if i % 50 == 0:
            print compute_accuracy(xs,ys,mnist.test.images, mnist.test.labels,keep_prob,sess,prediction)  # 每50次输出一下准确度

计算准确度函数
- 和上面的两个计算准确度的函数一致，就是多了个dropout的参数keep_prob

'''计算准确度函数'''
def compute_accuracy(xs,ys,X,y,keep_prob,sess,prediction):
    y_pre = sess.run(prediction,feed_dict={xs:X,keep_prob:1.0})       # 预测，这里的keep_prob是dropout时用的，防止过拟合
    correct_prediction = tf.equal(tf.argmax(y_pre,1),tf.argmax(y,1))  #tf.argmax 给出某个tensor对象在某一维上的其数据最大值所在的索引值,即为对应的数字，tf.equal 来检测我们的预测是否真实标签匹配
    accuracy = tf.reduce_mean(tf.cast(correct_prediction,tf.float32)) # 平均值即为准确度
    result = sess.run(accuracy,feed_dict={xs:X,ys:y,keep_prob:1.0})
    return result

3、运行结果

测试集上准确度
使用top命令查看占用的CPU和内存，还是很消耗CPU和内存的，所以上面只输出了四次我就终止了
由于我在虚拟机里运行的TensorFlow程序，分配了5G的内存，若是内存不够会报一个错误。

八、保存和提取神经网络

1、保存

定义要保存的数据

W = tf.Variable(initial_value=[[1,2,3],[3,4,5]], 
               name='weights', dtype=tf.float32)   # 注意需要指定name和dtype
b = tf.Variable(initial_value=[1,2,3], 
               name='biases', dtype=tf.float32)
init = tf.initialize_all_variables()

保存

saver = tf.train.Saver()
with tf.Session() as sess:
    sess.run(init)
    save_path = saver.save(sess, 'my_network/save_net.ckpt') # 保存目录，注意要在当前项目下建立my_network的目录
    print ('保存到 :',save_path)

2、提取

定义数据

W = tf.Variable(np.arange(6).reshape((2,3)), 
               name='weights', dtype=tf.float32) # 注意与之前保存的一致
b = tf.Variable(np.arange((3)), 
               name='biases', dtype=tf.float32)

restore提取

saver = tf.train.Saver() 
with tf.Session() as sess:
    saver.restore(sess,'my_network/save_net.ckpt')  
    print('weights:',sess.run(W))  # 输出一下结果
    print('biases:',sess.run(b))

以下来自`tensorflow-turorial`，使用`python3.5`

九、线性模型Linear Model

全部代码
使用MNIST数据集

1、加载MNIST数据集，并输出信息

'''Load MNIST data and print some information'''
data = input_data.read_data_sets("MNIST_data", one_hot = True)
print("Size of:")
print("\t training-set:\t\t{}".format(len(data.train.labels)))
print("\t test-set:\t\t\t{}".format(len(data.test.labels)))
print("\t validation-set:\t{}".format(len(data.validation.labels)))
print(data.test.labels[0:5])
data.test.cls = np.array([label.argmax() for label in data.test.labels])   # get the actual value
print(data.test.cls[0:5])

2、绘制9张图像

实现函数

'''define a funciton to plot 9 images'''
def plot_images(images, cls_true, cls_pred = None):
    '''
    @parameter images:   the images info
    @parameter cls_true: the true value of image
    @parameter cls_pred: the prediction value, default is None
    '''
    assert len(images) == len(cls_true) == 9  # only show 9 images
    fig, axes = plt.subplots(nrows=3, ncols=3)
    for i, ax in enumerate(axes.flat):
        ax.imshow(images[i].reshape(img_shape), cmap="binary")  # binary means black_white image
        # show the true and pred values
        if cls_pred is None:
            xlabel = "True: {0}".format(cls_true[i])
        else:
            xlabel = "True: {0},Pred: {1}".format(cls_true[i],cls_pred[i])
        ax.set_xlabel(xlabel)
        ax.set_xticks([])  # remove the ticks
        ax.set_yticks([])
    plt.show()

选择测试集中的9张图显示

'''show 9 images'''
images = data.test.images[0:9]
cls_true = data.test.cls[0:9]
plot_images(images, cls_true)

3、定义要训练的模型

定义placeholder

'''define the placeholder'''
X = tf.placeholder(tf.float32, [None, img_size_flat])    # None means the arbitrary number of labels, the features size is img_size_flat 
y_true = tf.placeholder(tf.float32, [None, num_classes]) # output size is num_classes
y_true_cls = tf.placeholder(tf.int64, [None])

定义weights和biases

'''define weights and biases'''
weights = tf.Variable(tf.zeros([img_size_flat, num_classes]))  # img_size_flat*num_classes
biases = tf.Variable(tf.zeros([num_classes]))

定义模型

'''define the model'''
logits = tf.matmul(X,weights) + biases 
y_pred = tf.nn.softmax(logits)
y_pred_cls = tf.argmax(y_pred, dimension=1)
cross_entropy = tf.nn.softmax_cross_entropy_with_logits(labels=y_true, 
                                                       logits=logits)
cost = tf.reduce_mean(cross_entropy)
'''define the optimizer'''
optimizer = tf.train.GradientDescentOptimizer(learning_rate=0.5).minimize(cost)

定义求准确度

'''define the accuracy'''
correct_prediction = tf.equal(y_pred_cls, y_true_cls)
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))

定义session

'''run the datagraph and use batch gradient descent'''
session = tf.Session()
session.run(tf.global_variables_initializer())
batch_size = 100

4、定义函数`optimize`进行bgd训练

'''define a function to run the optimizer'''
def optimize(num_iterations):
    '''
    @parameter num_iterations: the traning times
    '''
    for i in range(num_iterations):
        x_batch, y_true_batch = data.train.next_batch(batch_size)
        feed_dict_train = {X: x_batch,y_true: y_true_batch}
        session.run(optimizer, feed_dict=feed_dict_train)

5、定义输出准确度的函数

代码

feed_dict_test = {X: data.test.images, 
                  y_true: data.test.labels, 
                  y_true_cls: data.test.cls}        
'''define a function to print the accuracy'''    
def print_accuracy():
    acc = session.run(accuracy, feed_dict=feed_dict_test)
    print("Accuracy on test-set:{0:.1%}".format(acc))

输出：Accuracy on test-set:89.4%

6、定义绘制错误预测的图片函数

代码

'''define a function to plot the error prediciton'''    
def plot_example_errors():
    correct, cls_pred = session.run([correct_prediction, y_pred_cls], feed_dict=feed_dict_test) 
    incorrect = (correct == False)
    images = data.test.images[incorrect]  # get the prediction error images
    cls_pred = cls_pred[incorrect]        # get prediction value
    cls_true = data.test.cls[incorrect]   # get true value
    plot_images(images[0:9], cls_true[0:9], cls_pred[0:9])

输出：

7、定义可视化权重的函数

代码

'''define a fucntion to plot weights'''
def plot_weights():
    w = session.run(weights)
    w_min = np.min(w)
    w_max = np.max(w)
    fig, axes = plt.subplots(3, 4)
    fig.subplots_adjust(0.3, 0.3)
    for i, ax in enumerate(axes.flat):
        if i<10:
            image = w[:,i].reshape(img_shape)
            ax.set_xlabel("Weights: {0}".format(i))
            ax.imshow(image, vmin=w_min,vmax=w_max,cmap="seismic")
        ax.set_xticks([])
        ax.set_yticks([])
    plt.show()

输出：

8、定义输出`confusion_matrix`的函数

代码：

'''define a function to printand plot the confusion matrix using scikit-learn.'''   
def print_confusion_martix():
    cls_true = data.test.cls  # test set actual value 
    cls_pred = session.run(y_pred_cls, feed_dict=feed_dict_test)  # test set predict value
    cm = confusion_matrix(y_true=cls_true,y_pred=cls_pred)        # use sklearn confusion_matrix
    print(cm)
    plt.imshow(cm, interpolation='nearest',cmap=plt.cm.Blues) # Plot the confusion matrix as an image.
    plt.tight_layout()
    plt.colorbar()
    tick_marks = np.arange(num_classes)
    tick_marks = np.arange(num_classes)
    plt.xticks(tick_marks, range(num_classes))
    plt.yticks(tick_marks, range(num_classes))
    plt.xlabel('Predicted')
    plt.ylabel('True')    
    plt.show()

输出：

十：CNN

全部代码
使用MNIST数据集
加载数据，绘制9张图等函数与上面一致，readme中不再写出

1、定义CNN所需要的变量

'''define cnn description'''
filter_size1 = 5     # the first conv filter size is 5x5 
num_filters1 = 32    # there are 32 filters
filter_size2 = 5     # the second conv filter size
num_filters2 = 64    # there are 64 filters
fc_size = 1024       # fully-connected layer

2、初始化weights和biases的函数

'''define a function to intialize weights'''
def initialize_weights(shape):
    '''
    @param shape：the shape of weights
    '''
    return tf.Variable(tf.truncated_normal(shape=shape, stddev=0.1))
'''define a function to intialize biases'''
def initialize_biases(length):
    '''
    @param length: the length of biases, which is a vector
    '''
    return tf.Variable(tf.constant(0.1,shape=[length]))

3、定义卷积操作和池化（如果使用的话）的函数

'''define a function to do conv and pooling if used'''
def conv_layer(input, 
               num_input_channels,
               filter_size,
               num_output_filters,
               use_pooling=True):
    '''
    @param input: the input of previous layer's output
    @param num_input_channels: input channels
    @param filter_size: the weights filter size
    @param num_output_filters: the output number channels
    @param use_pooling: if use pooling operation
    '''
    shape = [filter_size, filter_size, num_input_channels, num_output_filters]
    weights = initialize_weights(shape=shape)
    biases = initialize_biases(length=num_output_filters)   # one for each filter
    layer = tf.nn.conv2d(input=input, filter=weights, strides=[1,1,1,1], padding='SAME')
    layer += biases
    if use_pooling:
        layer = tf.nn.max_pool(value=layer,
                               ksize=[1,2,2,1],
                               strides=[1,2,2,1],
                               padding="SAME")   # the kernel function size is 2x2,so the ksize=[1,2,2,1]
    layer = tf.nn.relu(layer)
    return layer, weights

4、定义将卷积层展开的函数

'''define a function to flat conv layer'''
def flatten_layer(layer):
    '''
    @param layer: the conv layer
    '''
    layer_shape = layer.get_shape() # get the shape of the layer(layer_shape == [num_images, img_height, img_width, num_channels])
    num_features = layer_shape[1:4].num_elements()  # [1:4] means the last three demension, namely the flatten size
    layer_flat = tf.reshape(layer, [-1, num_features])   # reshape to flat,-1 means don't care about the number of images
    return layer_flat, num_features

5、定义全连接层的函数

'''define a function to do fully-connected'''
def fc_layer(input, num_inputs, num_outputs, use_relu=True):
    '''
    @param input: the input
    @param num_inputs: the input size
    @param num_outputs: the output size
    @param use_relu: if use relu activation function
    '''
    weights = initialize_weights(shape=[num_inputs, num_outputs])
    biases = initialize_biases(num_outputs)
    layer = tf.matmul(input, weights) + biases
    if use_relu:
        layer = tf.nn.relu(layer)
    return layer

6、定义模型

定义placeholder

'''define the placeholder'''
X = tf.placeholder(tf.float32, shape=[None, img_flat_size], name="X")
X_image = tf.reshape(X, shape=[-1, img_size, img_size, num_channels])  # reshape to the image shape
y_true = tf.placeholder(tf.float32, [None, num_classes], name="y_true")
y_true_cls = tf.argmax(y_true, axis=1)
keep_prob = tf.placeholder(tf.float32)  # drop out placeholder

定义卷积、dropout、和全连接

'''define the cnn model'''
layer_conv1, weights_conv1 = conv_layer(input=X_image, num_input_channels=num_channels, 
                                       filter_size=filter_size1, 
                                       num_output_filters=num_filters1,
                                       use_pooling=True)
print("conv1:",layer_conv1)
layer_conv2, weights_conv2 = conv_layer(input=layer_conv1, num_input_channels=num_filters1, 
                                        filter_size=filter_size2,
                                        num_output_filters=num_filters2,
                                        use_pooling=True)
print("conv2:",layer_conv2)
layer_flat, num_features = flatten_layer(layer_conv2) # the num_feature is 7x7x36=1764
print("flatten layer:", layer_flat)  
layer_fc1 = fc_layer(layer_flat, num_features, fc_size, use_relu=True)
print("fully-connected layer1:", layer_fc1)
layer_drop_out = tf.nn.dropout(layer_fc1, keep_prob)   # dropout operation
layer_fc2 = fc_layer(layer_drop_out, fc_size, num_classes,use_relu=False)
print("fully-connected layer2:", layer_fc2)
y_pred = tf.nn.softmax(layer_fc2)
y_pred_cls = tf.argmax(y_pred, axis=1)
cross_entropy = tf.nn.softmax_cross_entropy_with_logits(labels=y_true, 
                                                       logits=layer_fc2)
cost = tf.reduce_mean(cross_entropy)
optimizer = tf.train.AdamOptimizer(learning_rate=1e-3).minimize(cost)  # use AdamOptimizer优化

定义求准确度

'''define accuracy'''
correct_prediction = tf.equal(y_true_cls, y_pred_cls)
accuracy = tf.reduce_mean(tf.cast(correct_prediction,dtype=tf.float32))

7、定义训练的函数`optimize`，使用bgd

代码：

'''define a function to run train the model with bgd'''
total_iterations = 0  # record the total iterations
def optimize(num_iterations):
    '''
    @param num_iterations: the total interations of train batch_size operation
    '''
    global total_iterations
    start_time = time.time()
    for i in range(total_iterations,total_iterations + num_iterations):
        x_batch, y_batch = data.train.next_batch(batch_size)
        feed_dict = {X: x_batch, y_true: y_batch, keep_prob: 0.5}
        session.run(optimizer, feed_dict=feed_dict)
        if i % 10 == 0:
            acc = session.run(accuracy, feed_dict=feed_dict)
            msg = "Optimization Iteration: {0:>6}, Training Accuracy: {1:>6.1%}"    # {:>6}means the fixed width,{1:>6.1%}means the fixed width is 6 and keep 1 decimal place         
            print(msg.format(i + 1, acc))
    total_iterations += num_iterations
    end_time = time.time()
    time_dif = end_time-start_time
    print("time usage:"+str(timedelta(seconds=int(round(time_dif)))))

输出：

Optimization Iteration:    651, Training Accuracy:  99.0%
Optimization Iteration:    661, Training Accuracy:  99.0%
Optimization Iteration:    671, Training Accuracy:  99.0%
Optimization Iteration:    681, Training Accuracy:  99.0%
Optimization Iteration:    691, Training Accuracy:  99.0%
Optimization Iteration:    701, Training Accuracy:  99.0%
Optimization Iteration:    711, Training Accuracy:  99.0%
Optimization Iteration:    721, Training Accuracy:  99.0%
Optimization Iteration:    731, Training Accuracy:  99.0%
Optimization Iteration:    741, Training Accuracy: 100.0%
Optimization Iteration:    751, Training Accuracy:  99.0%
Optimization Iteration:    761, Training Accuracy:  99.0%
Optimization Iteration:    771, Training Accuracy:  97.0%
Optimization Iteration:    781, Training Accuracy:  96.0%
Optimization Iteration:    791, Training Accuracy:  98.0%
Optimization Iteration:    801, Training Accuracy: 100.0%
Optimization Iteration:    811, Training Accuracy: 100.0%
Optimization Iteration:    821, Training Accuracy:  97.0%
Optimization Iteration:    831, Training Accuracy:  98.0%
Optimization Iteration:    841, Training Accuracy:  99.0%
Optimization Iteration:    851, Training Accuracy:  99.0%
Optimization Iteration:    861, Training Accuracy:  99.0%
Optimization Iteration:    871, Training Accuracy:  96.0%
Optimization Iteration:    881, Training Accuracy:  99.0%
Optimization Iteration:    891, Training Accuracy:  99.0%
Optimization Iteration:    901, Training Accuracy:  98.0%
Optimization Iteration:    911, Training Accuracy:  99.0%
Optimization Iteration:    921, Training Accuracy:  99.0%
Optimization Iteration:    931, Training Accuracy:  99.0%
Optimization Iteration:    941, Training Accuracy:  98.0%
Optimization Iteration:    951, Training Accuracy: 100.0%
Optimization Iteration:    961, Training Accuracy:  99.0%
Optimization Iteration:    971, Training Accuracy:  98.0%
Optimization Iteration:    981, Training Accuracy:  99.0%
Optimization Iteration:    991, Training Accuracy: 100.0%
time usage:0:07:07

8、定义批量预测的函数，方便输出训练错的图像

batch_size_test = 256
def print_test_accuracy(print_error=False,print_confusion_matrix=False):
    '''
    @param print_error: whether plot the error images
    @param print_confusion_matrix: whether plot the confusion_matrix
    '''
    num_test = len(data.test.images)   
    cls_pred = np.zeros(shape=num_test, dtype=np.int)  # declare the cls_pred
    i = 0
    #predict the test set using batch_size
    while i < num_test:
        j = min(i + batch_size_test, num_test)
        images = data.test.images[i:j,:]
        labels = data.test.labels[i:j,:]
        feed_dict = {X:images,y_true:labels,keep_prob:0.5}
        cls_pred[i:j] = session.run(y_pred_cls,feed_dict=feed_dict)
        i = j
    cls_true = data.test.cls
    correct = (cls_true == cls_pred)
    correct_sum = correct.sum()   # correct predictions
    acc = float(correct_sum)/num_test
    msg = "Accuracy on Test-Set: {0:.1%} ({1} / {2})"
    print(msg.format(acc, correct_sum, num_test))    
    if print_error:
        plot_error_pred(cls_pred,correct)
    if print_confusion_matrix:
        plot_confusin_martrix(cls_pred)

9、定义可视化卷积核权重的函数

代码：

'''define a function to plot conv weights'''
def plot_conv_weights(weights,input_channel=0):
    '''
    @param weights: the conv filter weights, for example: the weights_conv1 and weights_conv2, which are 4 dimension [filter_size, filter_size, num_input_channels, num_output_filters]
    @param input_channel: the input_channels
    '''
    w = session.run(weights)
    w_min = np.min(w)
    w_max = np.max(w)
    num_filters = w.shape[3]   # get the number of filters
    num_grids = math.ceil(math.sqrt(num_filters))
    fig, axes = plt.subplots(num_grids, num_grids)
    for i, ax in enumerate(axes.flat):
        if i < num_filters:
            img = w[:,:,input_channel,i]   # the ith weight
            ax.imshow(img,vmin=w_min,vmax=w_max,interpolation="nearest",cmap='seismic')
        ax.set_xticks([])
        ax.set_yticks([])
    plt.show()

输出：
- 第一层：
- 第二层：

10、定义可视化卷积层输出的函数

代码：

'''define a function to plot conv output layer'''
def plot_conv_layer(layer, image):
    '''
    @param layer: the conv layer, which is also a image after conv
    @param image: the image info
    '''
    feed_dict = {X:[image]}
    values = session.run(layer, feed_dict=feed_dict)
    num_filters = values.shape[3]   # get the number of filters
    num_grids = math.ceil(math.sqrt(num_filters))
    fig, axes = plt.subplots(num_grids,num_grids)
    for i, ax in enumerate(axes.flat):
        if i < num_filters:
            img = values[0,:,:,i]
            ax.imshow(img, interpolation="nearest",cmap="binary")
        ax.set_xticks([])
        ax.set_yticks([])
    plt.show()

输出：
- 第一层：
- 第二层：

十一：使用prettytensor实现CNNModel

全部代码
使用MNIST数据集
加载数据，绘制9张图等函数与九一致，readme中不再写出

1、定义模型

定义placeholder,与之前的一致

'''declare the placeholder'''
X = tf.placeholder(tf.float32, [None, img_flat_size], name="X")
X_img = tf.reshape(X, shape=[-1,img_size,img_size, num_channels])
y_true = tf.placeholder(tf.float32, shape=[None, num_classes], name="y_true")
y_true_cls = tf.argmax(y_true,1)

使用prettytensor实现CNN模型

'''define the cnn model with prettytensor'''
x_pretty = pt.wrap(X_img)
with pt.defaults_scope():   # or pt.defaults_scope(activation_fn=tf.nn.relu) if just use one activation function
    y_pred, loss = x_pretty.\
        conv2d(kernel=5, depth=16, activation_fn=tf.nn.relu, name="conv_layer1").\
        max_pool(kernel=2, stride=2).\
        conv2d(kernel=5, depth=36, activation_fn=tf.nn.relu, name="conv_layer2").\
        max_pool(kernel=2, stride=2).\
        flatten().\
        fully_connected(size=128, activation_fn=tf.nn.relu, name="fc_layer1").\
        softmax_classifier(num_classes=num_classes, labels=y_true)

获取卷积核的权重(后续可视化)

'''define a function to get weights'''
def get_weights_variable(layer_name):
    with tf.variable_scope(layer_name, reuse=True):
        variable = tf.get_variable("weights")
    return variable
conv1_weights = get_weights_variable("conv_layer1")
conv2_weights = get_weights_variable("conv_layer2")

定义optimizer训练，和之前的一样了

'''define optimizer to train'''
optimizer = tf.train.AdamOptimizer().minimize(loss)
y_pred_cls = tf.argmax(y_pred,1)
correct_prediction = tf.equal(y_pred_cls, y_true_cls)
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
session = tf.Session()
session.run(tf.global_variables_initializer())

十二：CNN,保存和加载模型，使用Early Stopping

全部代码
使用MNIST数据集
加载数据，绘制9张图等函数与九一致，readme中不再写出
CNN模型的定义和十一中的一致，readme中不再写出

1、保存模型

'''define a Saver to save the network'''
saver = tf.train.Saver()
save_dir = "checkpoints/"
if not os.path.exists(save_dir):
    os.makedirs(save_dir)
save_path = os.path.join(save_dir, 'best_validation')

保存session,对应到下面2中的Early Stopping，将最好的模型保存

saver.save(sess=session, save_path=save_path)

2、Early Stopping

'''declear the train info'''
train_batch_size = 64
best_validation_accuracy = 0.0
last_improvement = 0
require_improvement_iterations = 1000
total_iterations = 0
'''define a function to optimize the optimizer'''
def optimize(num_iterations):
    global total_iterations
    global best_validation_accuracy
    global last_improvement
    start_time = time.time()
    for i in range(num_iterations):
        total_iterations += 1
        X_batch, y_true_batch = data.train.next_batch(train_batch_size)
        feed_dict_train = {X: X_batch,
                     y_true: y_true_batch}
        session.run(optimizer, feed_dict=feed_dict_train)
        if (total_iterations%100 == 0) or (i == num_iterations-1):
            acc_train = session.run(accuracy, feed_dict=feed_dict_train)
            acc_validation, _ = validation_accuracy()
            if acc_validation > best_validation_accuracy:
                best_validation_accuracy = acc_validation
                last_improvement = total_iterations
                saver.save(sess=session, save_path=save_path)
                improved_str = "*"
            else:
                improved_str = ""
            msg = "Iter: {0:>6}, Train_batch accuracy:{1:>6.1%}, validation acc:{2:>6.1%} {3}"
            print(msg.format(i+1, acc_train, acc_validation, improved_str))
        if total_iterations-last_improvement > require_improvement_iterations:
            print('No improvement found in a while, stop running')
            break
    end_time = time.time()
    time_diff = end_time-start_time
    print("Time usage:" + str(timedelta(seconds=int(round(time_diff)))))

调用optimize(10000)输出信息

Iter:   5100, Train_batch accuracy:100.0%, validation acc: 98.8% *
Iter:   5200, Train_batch accuracy:100.0%, validation acc: 98.3% 
Iter:   5300, Train_batch accuracy:100.0%, validation acc: 98.7% 
Iter:   5400, Train_batch accuracy: 98.4%, validation acc: 98.6% 
Iter:   5500, Train_batch accuracy: 98.4%, validation acc: 98.6% 
Iter:   5600, Train_batch accuracy:100.0%, validation acc: 98.7% 
Iter:   5700, Train_batch accuracy: 96.9%, validation acc: 98.9% *
Iter:   5800, Train_batch accuracy:100.0%, validation acc: 98.6% 
Iter:   5900, Train_batch accuracy:100.0%, validation acc: 98.6% 
Iter:   6000, Train_batch accuracy: 98.4%, validation acc: 98.7% 
Iter:   6100, Train_batch accuracy:100.0%, validation acc: 98.7% 
Iter:   6200, Train_batch accuracy:100.0%, validation acc: 98.7% 
Iter:   6300, Train_batch accuracy: 98.4%, validation acc: 98.8% 
Iter:   6400, Train_batch accuracy: 98.4%, validation acc: 98.8% 
Iter:   6500, Train_batch accuracy:100.0%, validation acc: 98.7% 
Iter:   6600, Train_batch accuracy:100.0%, validation acc: 98.7% 
Iter:   6700, Train_batch accuracy:100.0%, validation acc: 98.8% 
No improvement found in a while, stop running
Time usage:0:18:43

可以看到最后10次输出（每100次输出一次）在验证集上准确度都没有提高，停止执行

3、小批量预测并计算准确率

因为需要预测测试集和验证集，这里参数指定需要的images

'''define a function to predict using batch'''
batch_size_predict = 256
def predict_cls(images, labels, cls_true):
    num_images = len(images)
    cls_pred = np.zeros(shape=num_images, dtype=np.int)
    i = 0
    while i < num_images:
        j = min(i+batch_size_predict, num_images)
        feed_dict = {X: images[i:j,:],
                     y_true: labels[i:j,:]}
        cls_pred[i:j] = session.run(y_pred_cls, feed_dict=feed_dict)
        i = j
    correct = (cls_true==cls_pred)
    return correct, cls_pred

测试集和验证集直接调用即可

def predict_cls_test():
    return predict_cls(data.test.images, data.test.labels, data.test.cls)

def predict_cls_validation():
    return predict_cls(data.validation.images, data.validation.labels, data.validation.cls)

计算验证集准确率（上面optimize函数中需要用到）

'''calculate the acc'''
def cls_accuracy(correct):
    correct_sum = correct.sum()
    acc = float(correct_sum)/len(correct)
    return acc, correct_sum
'''define a function to calculate the validation acc'''
def validation_accuracy():
    correct, _ = predict_cls_validation()
    return cls_accuracy(correct)

计算测试集准确率，并且输出错误的预测和confusion matrix

'''define a function to calculate test acc'''
def print_test_accuracy(show_example_errors=False,
                        show_confusion_matrix=False):
    correct, cls_pred = predict_cls_test()
    acc, num_correct = cls_accuracy(correct)
    num_images = len(correct)
    msg = "Accuracy on Test-Set: {0:.1%} ({1} / {2})"
    print(msg.format(acc, num_correct, num_images))

    # Plot some examples of mis-classifications, if desired.
    if show_example_errors:
        print("Example errors:")
        plot_example_errors(cls_pred=cls_pred, correct=correct)

    # Plot the confusion matrix, if desired.
    if show_confusion_matrix:
        print("Confusion Matrix:")
        plot_confusion_matrix(cls_pred=cls_pred)

十二：模型融合

全部代码
使用MNIST数据集
一些方法和之前的一致，不在给出
其中训练了多个CNN 模型，然后取预测的平均值作为最后的预测结果

1、将测试集和验证集合并后，并重新划分

主要是希望训练时数据集有些变换，否则都是一样的数据去训练了，最后再融合意义不大

'''将training set和validation set合并，并重新划分'''
combine_images = np.concatenate([data.train.images, data.validation.images], axis=0)
combine_labels = np.concatenate([data.train.labels, data.validation.labels], axis=0)
print("合并后图片：", combine_images.shape)
print("合并后label：", combine_labels.shape)
combined_size = combine_labels.shape[0]
train_size = int(0.8*combined_size)
validation_size = combined_size - train_size
'''函数：将合并后的重新随机划分'''
def random_training_set():
    idx = np.random.permutation(combined_size)   # 将0-combined_size数字随机排列
    idx_train = idx[0:train_size]
    idx_validation = idx[train_size:]
    x_train = combine_images[idx_train, :]
    y_train = combine_labels[idx_train, :]
    
    x_validation = combine_images[idx_validation, :]
    y_validation = combine_images[idx_validation, :]
    return x_train, y_train, x_validation, y_validation

2、融合模型

加载训练好的模型，并输出每个模型在测试集的预测结果等

def ensemble_predictions():
    pred_labels = []
    test_accuracies = []
    validation_accuracies = []
    for i in range(num_networks):
        saver.restore(sess=session, save_path=get_save_path(i))
        test_acc = test_accuracy()
        test_accuracies.append(test_acc)
        validation_acc = validation_accuracy()
        validation_accuracies.append(validation_acc)
        msg = "网络：{0}，验证集：{1:.4f}，测试集{2:.4f}"
        print(msg.format(i, validation_acc, test_acc))
        pred = predict_labels(data.test.images)
        pred_labels.append(pred)
    return np.array(pred_labels),\
           np.array(test_accuracies),\
           np.array(validation_accuracies)

调用pred_labels, test_accuracies, val_accuracies = ensemble_predictions()
取均值：ensemble_pred_labels = np.mean(pred_labels, axis=0)
融合后的真实结果：ensemble_cls_pred = np.argmax(ensemble_pred_labels, axis=1)
其他一些信息：

ensemble_correct = (ensemble_cls_pred == data.test.cls)
ensemble_incorrect = np.logical_not(ensemble_correct)
print(test_accuracies)
best_net = np.argmax(test_accuracies)
print(best_net)
print(test_accuracies[best_net])
best_net_pred_labels = pred_labels[best_net, :, :]
best_net_cls_pred = np.argmax(best_net_pred_labels, axis=1)
best_net_correct = (best_net_cls_pred == data.test.cls)
best_net_incorrect = np.logical_not(best_net_correct)
print("融合后预测对的：", np.sum(ensemble_correct))
print("单个最好模型预测对的", np.sum(best_net_correct))
ensemble_better = np.logical_and(best_net_incorrect, ensemble_correct)  # 融合之后好于单个的个数
print(ensemble_better.sum())
best_net_better = np.logical_and(best_net_correct, ensemble_incorrect)  # 单个好于融合之后的个数
print(best_net_better.sum())

十二：Cifar-10数据集，使用`variable_scope`重复使用变量

全部代码
使用CIFAR-10数据集
创建了两个网络，一个用于训练，一个用于测试，测试使用的是训练好的权重参数，所以用到参数重用
网络结构

1、数据集

导入包：
- 这是别人实现好的下载和处理cifar-10数据集的diamante

import cifar10
from cifar10 import img_size, num_channels, num_classes

输出一些数据集信息

'''下载cifar10数据集, 大概163M'''
cifar10.maybe_download_and_extract()
'''加载数据集'''
images_train, cls_train, labels_train = cifar10.load_training_data()
images_test,  cls_test,  labels_test  = cifar10.load_test_data()

'''打印一些信息'''
class_names = cifar10.load_class_names()
print(class_names)
print("Size of:")
print("training set:\t\t{}".format(len(images_train)))
print("test set:\t\t\t{}".format(len(images_test)))

显示9张图片函数
- 相比之前的，加入了smooth

'''显示9张图片函数'''
def plot_images(images, cls_true, cls_pred=None, smooth=True):   # smooth是否平滑显示
    assert len(images) == len(cls_true) == 9
    fig, axes = plt.subplots(3,3)
    
    for i, ax in enumerate(axes.flat):
        if smooth:
            interpolation = 'spline16'
        else:
            interpolation = 'nearest'
        ax.imshow(images[i, :, :, :], interpolation=interpolation)
        cls_true_name = class_names[cls_true[i]]
        if cls_pred is None:
            xlabel = "True:{0}".format(cls_true_name)
        else:
            cls_pred_name = class_names[cls_pred[i]]
            xlabel = "True:{0}, Pred:{1}".format(cls_true_name, cls_pred_name)
        ax.set_xlabel(xlabel)
        ax.set_xticks([])
        ax.set_yticks([])
    plt.show()

2、定义`placeholder`

X = tf.placeholder(tf.float32, shape=[None, img_size, img_size, num_channels], name="X")
y_true = tf.placeholder(tf.float32, shape=[None, num_classes], name="y")
y_true_cls = tf.argmax(y_true, axis=1)

3、图片处理

单张图片处理
- 原图是32*32像素的，裁剪成24*24像素的
- 如果是训练集进行一些裁剪，翻转，饱和度等处理
- 如果是测试集，只进行简单的裁剪处理
- 这也是为什么使用variable_scope定义两个网络

'''单个图片预处理, 测试集只需要裁剪就行了'''
def pre_process_image(image, training):
    if training:
        image = tf.random_crop(image, size=[img_size_cropped, img_size_cropped, num_channels])  # 裁剪
        image = tf.image.random_flip_left_right(image)                  # 左右翻转
        image = tf.image.random_hue(image, max_delta=0.05)              # 色调调整
        image = tf.image.random_brightness(image, max_delta=0.2)        # 曝光
        image = tf.image.random_saturation(image, lower=0.0, upper=2.0) # 饱和度
        '''上面的调整可能pixel值超过[0, 1], 所以约束一下'''        
        image = tf.minimum(image, 1.0)
        image = tf.maximum(image, 0.0)
    else:
        image = tf.image.resize_image_with_crop_or_pad(image, target_height=img_size_cropped, 
                                              target_width=img_size_cropped)
    return image

多张图片处理
因为训练和测试是都是使用batch的方式
调用上面处理单张图片的函数
tf.map_fn(fn, elems)函数，前面一般是lambda函数，后面是所有的数据

'''调用上面的函数，处理多个图片images'''
def pre_process(images, training):
    images = tf.map_fn(lambda image: pre_process_image(image, training), images)   # tf.map_fn()使用lambda函数
    return images

4、定义tensorflow计算图

定义主网络图
- 使用prettytensor
- 分为training和test两个阶段

'''定义主网络函数'''
def main_network(images, training):
    x_pretty = pt.wrap(images)
    if training:
        phase = pt.Phase.train
    else:
        phase = pt.Phase.infer
    with pt.defaults_scope(activation_fn=tf.nn.relu, phase=phase):
        y_pred, loss = x_pretty.\
        conv2d(kernel=5, depth=64, name="layer_conv1", batch_normalize=True).\
        max_pool(kernel=2, stride=2).\
        conv2d(kernel=5, depth=64, name="layer_conv2").\
        max_pool(kernel=2, stride=2).\
        flatten().\
        fully_connected(size=256, name="layer_fc1").\
        fully_connected(size=128, name="layer_fc2").\
        softmax_classifier(num_classes, labels=y_true)
    return y_pred, loss

创建所有网络，包含预处理图片和主网络
- 需要使用variable_scope, 测试阶段需要reuse训练阶段的参数

'''创建所有网络, 包含预处理和主网络，'''
def create_network(training):
    # 使用variable_scope可以重复使用定义的变量，训练时创建新的，测试时重复使用
    with tf.variable_scope("network", reuse=not training):
        images = X
        images = pre_process(images=images, training=training)
        y_pred, loss = main_network(images=images, training=training)
    return y_pred, loss

创建训练阶段网络
- 定义一个global_step记录训练的次数，下面会将其保存到checkpoint,trainable为False就不会训练改变

'''训练阶段网络创建'''
global_step = tf.Variable(initial_value=0, 
                          name="global_step",
                          trainable=False) # trainable 在训练阶段不会改变
_, loss = create_network(training=True)
optimizer = tf.train.AdamOptimizer(learning_rate=0.0001).minimize(loss, global_step)

定义测试阶段网络
- 同时定义准确率

'''测试阶段网络创建'''
y_pred, _ = create_network(training=False)
y_pred_cls = tf.argmax(y_pred, dimension=1)
correct_prediction = tf.equal(y_pred_cls, y_true_cls)
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))

5、获取权重和每层的输出值信息

获取权重变量

def get_weights_variable(layer_name):
    with tf.variable_scope("network/" + layer_name, reuse=True):
        variable = tf.get_variable("weights")
    return variable 
weights_conv1 = get_weights_variable("layer_conv1")
weights_conv2 = get_weights_variable("layer_conv2")

获取每层的输出变量

def get_layer_output(layer_name):
    tensor_name = "network/" + layer_name + "/Relu:0"
    tensor = tf.get_default_graph().get_tensor_by_name(tensor_name)
    return tensor
output_conv1 = get_layer_output("layer_conv1")
output_conv2 = get_layer_output("layer_conv2")

6、保存和加载计算图参数

因为第一次不会加载，所以放到try中判断

'''执行tensorflow graph'''
session = tf.Session()
save_dir = "checkpoints/"
if not os.path.exists(save_dir):
    os.makedirs(save_dir)
save_path = os.path.join(save_dir, 'cifat10_cnn')

'''尝试存储最新的checkpoint, 可能会失败，比如第一次运行checkpoint不存在等'''
try:
    print("开始存储最新的存储...")
    last_chk_path = tf.train.latest_checkpoint(save_dir)
    saver.restore(session, save_path=last_chk_path)
    print("存储点来自：", last_chk_path)
except:
    print("存储错误, 初始化变量")
    session.run(tf.global_variables_initializer())

7、训练

获取batch

'''SGD'''
train_batch_size = 64
def random_batch():
    num_images = len(images_train)
    idx = np.random.choice(num_images, size=train_batch_size, replace=False)
    x_batch = images_train[idx, :, :, :]
    y_batch = labels_train[idx, :]
    return x_batch, y_batch

训练网络
- 每1000次保存一下checkpoint
- 因为上面会restored已经保存训练的网络，同时也保存了训练的次数，所以可以接着训练

def optimize(num_iterations):
    start_time = time.time()
    for i in range(num_iterations):
        x_batch, y_batch = random_batch()
        feed_dict_train = {X: x_batch, y_true: y_batch}
        i_global, _ = session.run([global_step, optimizer], feed_dict=feed_dict_train)
        if (i_global%100==0) or (i == num_iterations-1):
            batch_acc = session.run(accuracy, feed_dict=feed_dict_train)
            msg = "global step: {0:>6}, training batch accuracy: {1:>6.1%}"
            print(msg.format(i_global, batch_acc))
        if(i_global%1000==0) or (i==num_iterations-1):
            saver.save(session, save_path=save_path,
                       global_step=global_step)
            print("保存checkpoint")
    end_time = time.time()
    time_diff = end_time-start_time
    print("耗时：", str(timedelta(seconds=int(round(time_diff)))))

十三、Inception model (GoogleNet)

全部代码
使用训练好的inception model,因为模型很复杂，一般的电脑运行不起来的。
网络结构

1、下载和加载inception model

因为是预训练好的模型，所以无需我们定义结构了
导入包
- 这里 inception是别人实现好的下载的代码

import numpy as np
import tensorflow as tf
from matplotlib import pyplot as plt
import inception # 第三方类加载inception model
import os

下载和加载模型

'''下载和加载inception model'''
inception.maybe_download()
model = inception.Inception()

预测和显示图片函数

'''预测和显示图片'''
def classify(image_path):
    plt.imshow(plt.imread(image_path))
    plt.show()
    pred = model.classify(image_path=image_path)
    model.print_scores(pred=pred, k=10, only_first_name=True)

显示调整后的图片
- 因为 inception model要求输入图片为 299*299 像素的，所以它会resize成这个大小然后作为输入

'''显示处理后图片的样式'''
def plot_resized_image(image_path):
    resized_image = model.get_resized_image(image_path)
    plt.imshow(resized_image, interpolation='nearest')
    plt.show()
plot_resized_image(image_path)

十四、迁移学习 Transfer Learning

全部代码
网络结构还是使用上一节的inception model, 去掉最后的全连接层，然后重新构建全连接层进行训练
- 因为inception model 是训练好的，前面的卷积层用于捕捉特征, 而后面的全连接层可用于分类，所以我们训练全连接层即可
因为要计算每张图片的transfer values,所以使用一个cache缓存transfer-values，第一次计算完成后，后面重新运行直接读取存储的结果，这样比较节省时间
- transfer values是inception model在Softmax层前一层的值
- cifar-10数据集, 我放在实验室电脑上运行了几个小时才得到transfer values，还是比较慢的
总之最后相当于训练下面的神经网络，对应的 transfer-values作为输入

1、准备工作

导入包

import numpy as np
import tensorflow as tf
import prettytensor as pt
from matplotlib import pyplot as plt
import time
from datetime import timedelta
import os
import inception   # 第三方下载inception model的代码
from inception import transfer_values_cache  # cache
import cifar10     # 也是第三方的库，下载cifar-10数据集
from cifar10 import num_classes

下载cifar-10数据集

'''下载cifar-10数据集'''
cifar10.maybe_download_and_extract()
class_names = cifar10.load_class_names()
print("所有类别是：",class_names)
'''训练和测试集'''
images_train, cls_train, labels_train = cifar10.load_training_data()
images_test,  cls_test,  labels_test  = cifar10.load_test_data()

下载和加载inception model

'''下载inception model'''
inception.maybe_download()
model = inception.Inception()

计算cifar-10训练集和测试集在inception model上的transfer values
- 因为计算非常耗时，这里第一次运行存储到本地，以后再运行直接读取即可
- transfer values的shape是(dataset size, 2048)，因为是softmax层的前一层

'''训练和测试的cache的路径'''
file_path_cache_train = os.path.join(cifar10.data_path, 'inception_cifar10_train.pkl')
file_path_cache_test = os.path.join(cifar10.data_path, 'inception_cifar10_test.pkl')

print('处理训练集上的transfer-values.......... ')
image_scaled = images_train * 255.0  # cifar-10的pixel是0-1的, shape=(50000, 32, 32, 3)
transfer_values_train = transfer_values_cache(cache_path=file_path_cache_train,
                                              images=image_scaled, 
                                              model=model)  # shape=(50000, 2048)
print('处理测试集上的transfer-values.......... ')
images_scaled = images_test * 255.0
transfer_values_test = transfer_values_cache(cache_path=file_path_cache_test,
                                             model=model,
                                             images=images_scaled)
print("transfer_values_train: ",transfer_values_train.shape)
print("transfer_values_test: ",transfer_values_test.shape)

可视化一张图片对应的transfer values

'''显示transfer values'''
def plot_transfer_values(i):
    print("输入图片：")
    plt.imshow(images_test[i], interpolation='nearest')
    plt.show()
    print('transfer values --> 此图片在inception model上')
    img = transfer_values_test[i]
    img = img.reshape((32, 64))
    plt.imshow(img, interpolation='nearest', cmap='Reds')
    plt.show()
plot_transfer_values(16)

2、分析`transfer values`

(1) 使用PCA主成分分析

将数据降到2维，可视化，因为transfer values是已经捕捉到的特征，所以可视化应该是可以隐约看到不同类别的数据是有区别的
取3000个数据观察（因为PCA也是比较耗时的）

'''使用PCA分析transfer values'''
from sklearn.decomposition import PCA
pca = PCA(n_components=2)
transfer_values = transfer_values_train[0:3000]  # 取3000个，大的话计算量太大
cls = cls_train[0:3000]
print(transfer_values.shape)
transfer_values_reduced = pca.fit_transform(transfer_values)
print(transfer_values_reduced.shape)

可视化降维后的数据

## 显示降维后的transfer values
def plot_scatter(values, cls):
    from matplotlib import cm as cm
    cmap = cm.rainbow(np.linspace(0.0, 1.0, num_classes))
    colors = cmap[cls]
    x = values[:, 0]
    y = values[:, 1]
    plt.scatter(x, y, color=colors)
    plt.show()
plot_scatter(transfer_values_reduced, cls)

(2) 使用TSNE主成分分析

因为t-SNE运行非常慢，所以这里先用PCA将到50维

from sklearn.manifold import TSNE
pca = PCA(n_components=50)
transfer_values_50d = pca.fit_transform(transfer_values)
tsne = TSNE(n_components=2)
transfer_values_reduced = tsne.fit_transform(transfer_values_50d)
print("最终降维后：", transfer_values_reduced.shape)
plot_scatter(transfer_values_reduced, cls)

数据区分还是比较明显的

3、创建我们自己的网络

使用prettytensor创建一个全连接层，使用softmax作为分类

'''创建网络'''
transfer_len = model.transfer_len   # 获取transfer values的大小，这里是2048
x = tf.placeholder(tf.float32, shape=[None, transfer_len], name="x")
y_true = tf.placeholder(tf.float32, shape=[None, num_classes], name="y")
y_true_cls = tf.argmax(y_true, axis=1)
x_pretty = pt.wrap(x)
with pt.defaults_scope(activation_fn=tf.nn.relu):
    y_pred, loss = x_pretty.\
        fully_connected(1024, name="layer_fc1").\
        softmax_classifier(num_classes, labels=y_true)

优化器

'''优化器'''
global_step = tf.Variable(initial_value=0, name="global_step", trainable=False)
optimizer = tf.train.AdamOptimizer(0.0001).minimize(loss, global_step)

准确度

'''accuracy'''
y_pred_cls = tf.argmax(y_pred, axis=1)
correct_prediction = tf.equal(y_pred_cls, y_true_cls)
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))

SGD训练

'''SGD 训练'''
session = tf.Session()
session.run(tf.initialize_all_variables())
train_batch_size = 64
def random_batch():
    num_images = len(images_train)
    idx = np.random.choice(num_images, 
                           size=train_batch_size,
                           replace=False)
    x_batch = transfer_values_train[idx]
    y_batch = labels_train[idx]
    return x_batch, y_batch
def optimize(num_iterations):
    start_time = time.time()
    for i in range(num_iterations):
        x_batch, y_true_batch = random_batch()
        feed_dict_train = {x: x_batch,
                           y_true: y_true_batch}
        i_global, _ = session.run([global_step, optimizer], feed_dict=feed_dict_train)
        if (i_global % 100 == 0) or (i==num_iterations-1):
            batch_acc = session.run(accuracy, feed_dict=feed_dict_train)
            msg = "Global Step: {0:>6}, Training Batch Accuracy: {1:>6.1%}"
            print(msg.format(i_global, batch_acc))            
    end_time = time.time()
    time_diff = end_time - start_time
    print("耗时：", str(timedelta(seconds=int(round(time_diff)))))

使用batch size预测测试集数据

'''batch 预测'''
batch_size = 256
def predict_cls(transfer_values, labels, cls_true):
    num_images = len(images_test)
    cls_pred = np.zeros(shape=num_images, dtype=np.int)
    i = 0
    while i < num_images:
        j = min(i + batch_size, num_images)
        feed_dict = {x: transfer_values[i:j],
                     y_true: labels[i:j]}
        cls_pred[i:j] = session.run(y_pred_cls, feed_dict=feed_dict)
        i = j
    correct = (cls_true == cls_pred)
    return correct, cls_pred

RNN循环神经网络

开启新篇章，以下内容为RNN相关内容
关于RNN的基本内容可以查看我的博客：点击查看

一、实现MNIST分类

1、说明

关于RNN的基本内容参考我的博客：点击查看
使用MNIST数据集，全部代码：点击查看
为什么可以使用RNN来进行分类，我们可以认为像素是有关联的
图片的大小是28x28的，每一行看作一个输入，共有28列，所以n_steps=28看完一张图片
所以输入的维度是(batch_size, n_steps, n_inputs)，输出就是(batch_size, n_classes)

2、实现

加载数据，声明超参数
- state_size是cell中的神经元个数
- n_steps截断梯度的步数，也就是学习多少步的依赖

print("tensorflow版本", tf.__version__)
'''读取数据'''
mnist = input_data.read_data_sets('MNIST_data', one_hot=True)
print("size of")
print('--training set:\t\t{}'.format(len(mnist.train.labels)))
print('--test set:\t\t\t{}'.format(len(mnist.test.labels)))
print('--validation set:\t{}'.format(len(mnist.validation.labels)))
'''定义超参数'''
learning_rate = 0.001
batch_size = 128
n_inputs = 28
n_steps = 28
state_size = 128
n_classes = 10

定义输入placeholder和权重，偏置
- 这里的输入权重和biases是不用定义的，因为cell中会计算

'''定义placehoder和初始化weights和biases'''
x = tf.placeholder(tf.float32, [batch_size, n_steps, n_inputs], name='x')
y = tf.placeholder(tf.float32, [batch_size, n_classes], name='y')
weights = {
    # (28, 128)
    #'in': tf.Variable(initial_value=tf.random_normal([n_inputs, state_size])),
    # (128, 10)
    'out': tf.Variable(tf.random_normal(shape=[state_size, n_classes], mean=0.0, stddev=1.0, 
                                       dtype=tf.float32, 
                                       seed=None, 
                                       name=None))
}
biases = {
    # (128, )
    #'in': tf.Variable(initial_value=tf.constant(0.1,shape=[state_size,]), trainable=True, collections=None, 
                     #validate_shape=True, 
                     #caching_device=None, name=None, 
                     #variable_def=None, dtype=None, 
                     #expected_shape=None, 
                     #import_scope=None),
    # (10, )
    'out': tf.Variable(initial_value=tf.constant(0.1, shape=[n_classes, ]), trainable=True, collections=None, 
                      validate_shape=True, 
                      caching_device=None, name=None, 
                      variable_def=None, dtype=None, 
                      expected_shape=None, 
                      import_scope=None)
}

RNN的cell
- 使用LSTM和dynamic_rnn的方式，关于dynamic_rnn不了解的还是请看我的博客
- 返回rnn的输出
- 经过n_steps=28遍历一张图片之后得到预测值，所以最后只需要最后一个的输出final_state来做最后的预测
  - final_state[1]就是LSTM的h state，就是对应的输出

'''定义RNN 结构'''
def RNN(X, weights, biases):
    '''这里输入X 不用再做权重的运算，cell中会自动运算（_linear函数）, 做了运算也没有实际意义，因为LSTM的cell输入的流向有多个'''
    # 原始的 X 是 3 维数据, 我们需要把它变成 2 维数据才能使用 weights 的矩阵乘法
    # X ==> (128 batch_size * 28 steps, 28 inputs)
    #X = tf.reshape(X, [-1, n_inputs])
    #X_in = tf.matmul(X, weights['in']) + biases['in']
    #  再换回3维
    # X_in ==> (128 batches, 28 steps, 128 hidden)
    #X_in = tf.reshape(X_in, shape=[-1, n_steps, state_size])
    '''cell中的计算方式1'''
    cell = tf.nn.rnn_cell.BasicLSTMCell(num_units=state_size)
    init_state = cell.zero_state(batch_size, dtype=tf.float32)
    rnn_outputs, final_state = tf.nn.dynamic_rnn(cell=cell,
                                                 inputs=X,
                                                 initial_state=init_state,
                                                 time_major=False)
    results = tf.matmul(final_state[1], weights['out']) + biases['out']
    return results

预测，损失和优化器

prediction = RNN(x, weights, biases)
losses = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits=prediction,
                                                                labels=y))
train_step = tf.train.AdamOptimizer(learning_rate).minimize(losses)
prediction_cls = tf.argmax(prediction, axis=1)
correct_pred = tf.equal(prediction_cls, tf.argmax(y, 1))
accuracy = tf.reduce_mean(tf.cast(correct_pred, tf.float32))

训练

def optimize(n_epochs):
    '''训练RNN'''
    with tf.Session() as sess:
        sess.run(tf.global_variables_initializer())
        for i in range(n_epochs):
            batch_x, batch_y = mnist.train.next_batch(batch_size)
            batch_x = batch_x.reshape([batch_size, n_steps, n_inputs])
            feed_dict = {x: batch_x, y: batch_y}
            sess.run(train_step, feed_dict=feed_dict)
            if i % 50 == 0:
                print("epoch: {0}, accuracy:{1}".format(i, sess.run(accuracy, feed_dict=feed_dict)))

3、运行结果

简单的在测试集上的准确率

epoch: 0, accuracy:0.1796875
epoch: 50, accuracy:0.7109375
epoch: 100, accuracy:0.828125
epoch: 150, accuracy:0.8359375
epoch: 200, accuracy:0.8984375
epoch: 250, accuracy:0.9296875
epoch: 300, accuracy:0.9375
epoch: 350, accuracy:0.921875
epoch: 400, accuracy:0.9609375
epoch: 450, accuracy:0.953125
epoch: 500, accuracy:0.921875
epoch: 550, accuracy:0.9296875
epoch: 600, accuracy:0.9609375
epoch: 650, accuracy:0.9375
epoch: 700, accuracy:0.9765625
epoch: 750, accuracy:0.96875
epoch: 800, accuracy:0.9375
epoch: 850, accuracy:0.9296875
epoch: 900, accuracy:0.9609375
epoch: 950, accuracy:0.96875

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TensorFlow

目录

一、TensorFlow介绍

1、什么是TensorFlow

2、TensorFlow强大之处

3、安装TensorFlow

二、TensorFlow基础架构

1、处理结构

2、一个例子

3、Session会话控制

4、Variable变量

5、Placeholder传入值

三、定义一个神经网络

1、添加层函数add_layer()

2、构建神经网络

3、可视化结果

四、TensorFlow可视化

1、TensorFlow的可视化工具tensorboard，可视化神经网路额结构

2、可视化训练过程

五、手写数字识别_1

1、说明

2、代码实现

六、手写数字识别_2

1、说明

2、代码

七、手写数字识别_3_CNN卷积神经网络

1、说明

2、代码实现

3、运行结果

八、保存和提取神经网络

1、保存

2、提取

以下来自tensorflow-turorial，使用python3.5

九、线性模型Linear Model

1、加载MNIST数据集，并输出信息

2、绘制9张图像

3、定义要训练的模型

4、定义函数optimize进行bgd训练

5、定义输出准确度的函数

6、定义绘制错误预测的图片函数

7、定义可视化权重的函数

8、定义输出confusion_matrix的函数

十：CNN

1、定义CNN所需要的变量

2、初始化weights和biases的函数

3、定义卷积操作和池化（如果使用的话）的函数

4、定义将卷积层展开的函数

5、定义全连接层的函数

6、定义模型

7、定义训练的函数optimize，使用bgd

8、定义批量预测的函数，方便输出训练错的图像

9、定义可视化卷积核权重的函数

10、定义可视化卷积层输出的函数

十一：使用prettytensor实现CNNModel

1、定义模型

十二：CNN,保存和加载模型，使用Early Stopping

1、保存模型

2、Early Stopping

3、 小批量预测并计算准确率

十二：模型融合

1、将测试集和验证集合并后，并重新划分

2、融合模型

十二：Cifar-10数据集，使用variable_scope重复使用变量

1、数据集

2、定义placeholder

3、图片处理

4、定义tensorflow计算图

5、获取权重和每层的输出值信息

6、保存和加载计算图参数

7、训练

十三、Inception model (GoogleNet)

1、下载和加载inception model

十四、迁移学习 Transfer Learning

1、准备工作

4、`Variable`变量

5、`Placeholder`传入值

1、添加层函数`add_layer()`

1、TensorFlow的可视化工具`tensorboard`，可视化神经网路额结构

以下来自`tensorflow-turorial`，使用`python3.5`

4、定义函数`optimize`进行bgd训练

8、定义输出`confusion_matrix`的函数

7、定义训练的函数`optimize`，使用bgd

3、小批量预测并计算准确率

十二：Cifar-10数据集，使用`variable_scope`重复使用变量

2、定义`placeholder`

2、分析`transfer values`