add some chapters

ch10/cifar10_train.py

+import  tensorflow as tf
+from    tensorflow.keras import layers, optimizers, datasets, Sequential
+import  os
+
+os.environ['TF_CPP_MIN_LOG_LEVEL']='2'
+tf.random.set_seed(2345)
+
+conv_layers = [ # 5 units of conv + max pooling
+    # unit 1
+    layers.Conv2D(64, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(64, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # unit 2
+    layers.Conv2D(128, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(128, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # unit 3
+    layers.Conv2D(256, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(256, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # unit 4
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # unit 5
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same')
+
+]
+
+
+
+def preprocess(x, y):
+    # [0~1]
+    x = 2*tf.cast(x, dtype=tf.float32) / 255.-1
+    y = tf.cast(y, dtype=tf.int32)
+    return x,y
+
+
+(x,y), (x_test, y_test) = datasets.cifar10.load_data()
+y = tf.squeeze(y, axis=1)
+y_test = tf.squeeze(y_test, axis=1)
+print(x.shape, y.shape, x_test.shape, y_test.shape)
+
+
+train_db = tf.data.Dataset.from_tensor_slices((x,y))
+train_db = train_db.shuffle(1000).map(preprocess).batch(128)
+
+test_db = tf.data.Dataset.from_tensor_slices((x_test,y_test))
+test_db = test_db.map(preprocess).batch(64)
+
+sample = next(iter(train_db))
+print('sample:', sample[0].shape, sample[1].shape,
+      tf.reduce_min(sample[0]), tf.reduce_max(sample[0]))
+
+
+def main():
+
+    # [b, 32, 32, 3] => [b, 1, 1, 512]
+    conv_net = Sequential(conv_layers)
+
+    fc_net = Sequential([
+        layers.Dense(256, activation=tf.nn.relu),
+        layers.Dense(128, activation=tf.nn.relu),
+        layers.Dense(10, activation=None),
+    ])
+
+    conv_net.build(input_shape=[None, 32, 32, 3])
+    fc_net.build(input_shape=[None, 512])
+    conv_net.summary()
+    fc_net.summary()
+    optimizer = optimizers.Adam(lr=1e-4)
+
+    # [1, 2] + [3, 4] => [1, 2, 3, 4]
+    variables = conv_net.trainable_variables + fc_net.trainable_variables
+
+    for epoch in range(50):
+
+        for step, (x,y) in enumerate(train_db):
+
+            with tf.GradientTape() as tape:
+                # [b, 32, 32, 3] => [b, 1, 1, 512]
+                out = conv_net(x)
+                # flatten, => [b, 512]
+                out = tf.reshape(out, [-1, 512])
+                # [b, 512] => [b, 10]
+                logits = fc_net(out)
+                # [b] => [b, 10]
+                y_onehot = tf.one_hot(y, depth=10)
+                # compute loss
+                loss = tf.losses.categorical_crossentropy(y_onehot, logits, from_logits=True)
+                loss = tf.reduce_mean(loss)
+
+            grads = tape.gradient(loss, variables)
+            optimizer.apply_gradients(zip(grads, variables))
+
+            if step %100 == 0:
+                print(epoch, step, 'loss:', float(loss))
+
+
+
+        total_num = 0
+        total_correct = 0
+        for x,y in test_db:
+
+            out = conv_net(x)
+            out = tf.reshape(out, [-1, 512])
+            logits = fc_net(out)
+            prob = tf.nn.softmax(logits, axis=1)
+            pred = tf.argmax(prob, axis=1)
+            pred = tf.cast(pred, dtype=tf.int32)
+
+            correct = tf.cast(tf.equal(pred, y), dtype=tf.int32)
+            correct = tf.reduce_sum(correct)
+
+            total_num += x.shape[0]
+            total_correct += int(correct)
+
+        acc = total_correct / total_num
+        print(epoch, 'acc:', acc)
+
+
+
+if __name__ == '__main__':
+    main()

ch10/nb.py

+#%%
+import  os
+os.environ['TF_CPP_MIN_LOG_LEVEL']='2'
+
+import  tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers, optimizers, datasets, Sequential
+
+
+
+#%% 
+x = tf.random.normal([2,5,5,3]) # 模拟输入，3通道，高宽为5
+# 需要根据[k,k,cin,cout]格式创建，4个卷积核
+w = tf.random.normal([3,3,3,4]) 
+# 步长为1, padding为0,
+out = tf.nn.conv2d(x,w,strides=1,padding=[[0,0],[0,0],[0,0],[0,0]])
+
+
+# %%
+x = tf.random.normal([2,5,5,3]) # 模拟输入，3通道，高宽为5
+# 需要根据[k,k,cin,cout]格式创建，4个卷积核
+w = tf.random.normal([3,3,3,4])
+# 步长为1, padding为1,
+out = tf.nn.conv2d(x,w,strides=1,padding=[[0,0],[1,1],[1,1],[0,0]])
+
+
+# %%
+x = tf.random.normal([2,5,5,3]) # 模拟输入，3通道，高宽为5
+w = tf.random.normal([3,3,3,4]) # 4个3x3大小的卷积核
+# 步长为,padding设置为输出、输入同大小
+# 需要注意的是, padding=same只有在strides=1时才是同大小
+out = tf.nn.conv2d(x,w,strides=1,padding='SAME')
+
+
+# %%
+x = tf.random.normal([2,5,5,3])
+w = tf.random.normal([3,3,3,4])
+# 高宽按3倍减少
+out = tf.nn.conv2d(x,w,strides=3,padding='SAME')
+print(out.shape)
+
+
+# %%
+# 根据[cout]格式创建偏置向量
+b = tf.zeros([4])
+# 在卷积输出上叠加偏置向量，它会自动broadcasting为[b,h',w',cout]
+out = out + b
+
+
+# %%
+# 创建卷积层类
+layer = layers.Conv2D(4,kernel_size=(3,4),strides=(2,1),padding='SAME')
+out = layer(x) # 前向计算
+out.shape
+
+
+# %%
+layer.kernel,layer.bias
+# 返回所有待优化张量列表
+layer.trainable_variables
+
+# %%
+from tensorflow.keras import Sequential
+network = Sequential([ # 网络容器
+    layers.Conv2D(6,kernel_size=3,strides=1), # 第一个卷积层, 6个3x3卷积核
+    layers.MaxPooling2D(pool_size=2,strides=2), # 高宽各减半的池化层
+    layers.ReLU(), # 激活函数
+    layers.Conv2D(16,kernel_size=3,strides=1), # 第二个卷积层, 16个3x3卷积核
+    layers.MaxPooling2D(pool_size=2,strides=2), # 高宽各减半的池化层
+    layers.ReLU(), # 激活函数
+    layers.Flatten(), # 打平层，方便全连接层处理
+
+    layers.Dense(120, activation='relu'), # 全连接层，120个节点
+    layers.Dense(84, activation='relu'), # 全连接层，84节点
+    layers.Dense(10) # 全连接层，10个节点
+                    ])
+# build一次网络模型，给输入X的形状，其中4为随意给的batchsz
+network.build(input_shape=(4, 28, 28, 1))
+# 统计网络信息
+network.summary()
+
+
+# %%
+# 导入误差计算，优化器模块
+from tensorflow.keras import losses, optimizers
+# 创建损失函数的类，在实际计算时直接调用类实例即可
+criteon = losses.CategoricalCrossentropy(from_logits=True)
+
+# %%
+    # 构建梯度记录环境
+    with tf.GradientTape() as tape: 
+        # 插入通道维度，=>[b,28,28,1]
+        x = tf.expand_dims(x,axis=3)
+        # 前向计算，获得10类别的预测分布，[b, 784] => [b, 10]
+        out = network(x)
+        # 真实标签one-hot编码，[b] => [b, 10]
+        y_onehot = tf.one_hot(y, depth=10)
+        # 计算交叉熵损失函数，标量
+        loss = criteon(y_onehot, out)
+    # 自动计算梯度
+    grads = tape.gradient(loss, network.trainable_variables)
+    # 自动更新参数
+    optimizer.apply_gradients(zip(grads, network.trainable_variables))
+
+
+# %%
+        # 记录预测正确的数量，总样本数量
+        correct, total = 0,0
+        for x,y in db_test: # 遍历所有训练集样本
+            # 插入通道维度，=>[b,28,28,1]
+            x = tf.expand_dims(x,axis=3)
+            # 前向计算，获得10类别的预测分布，[b, 784] => [b, 10]
+            out = network(x)
+            # 真实的流程时先经过softmax，再argmax
+            # 但是由于softmax不改变元素的大小相对关系，故省去
+            pred = tf.argmax(out, axis=-1)  
+            y = tf.cast(y, tf.int64)
+            # 统计预测正确数量
+            correct += float(tf.reduce_sum(tf.cast(tf.equal(pred, y),tf.float32)))
+            # 统计预测样本总数
+            total += x.shape[0]
+        # 计算准确率
+        print('test acc:', correct/total)
+
+
+# %%
+# 构造输入
+x=tf.random.normal([100,32,32,3])
+# 将其他维度合并，仅保留通道维度
+x=tf.reshape(x,[-1,3])
+# 计算其他维度的均值
+ub=tf.reduce_mean(x,axis=0)
+ub
+
+
+# %%
+# 创建BN层
+layer=layers.BatchNormalization()
+
+# %%
+network = Sequential([ # 网络容器
+    layers.Conv2D(6,kernel_size=3,strides=1),
+    # 插入BN层
+    layers.BatchNormalization(),
+    layers.MaxPooling2D(pool_size=2,strides=2),
+    layers.ReLU(),
+    layers.Conv2D(16,kernel_size=3,strides=1),
+    # 插入BN层
+    layers.BatchNormalization(),
+    layers.MaxPooling2D(pool_size=2,strides=2),
+    layers.ReLU(),
+    layers.Flatten(),
+    layers.Dense(120, activation='relu'),
+    # 此处也可以插入BN层
+    layers.Dense(84, activation='relu'), 
+    # 此处也可以插入BN层
+    layers.Dense(10)
+                    ])
+
+
+# %%
+    with tf.GradientTape() as tape: 
+        # 插入通道维度
+        x = tf.expand_dims(x,axis=3)
+        # 前向计算，设置计算模式，[b, 784] => [b, 10]
+        out = network(x, training=True)
+
+
+# %%
+        for x,y in db_test: # 遍历测试集
+            # 插入通道维度
+            x = tf.expand_dims(x,axis=3)
+            # 前向计算，测试模式
+            out = network(x, training=False)
+
+
+# %%
+def preprocess(x, y):
+    # [0~1]
+    x = 2*tf.cast(x, dtype=tf.float32) / 255.-1
+    y = tf.cast(y, dtype=tf.int32)
+    return x,y
+    
+# 在线下载，加载CIFAR10数据集
+(x,y), (x_test, y_test) = datasets.cifar100.load_data()
+# 删除y的一个维度，[b,1] => [b]
+y = tf.squeeze(y, axis=1)
+y_test = tf.squeeze(y_test, axis=1)
+# 打印训练集和测试集的形状
+print(x.shape, y.shape, x_test.shape, y_test.shape)
+# 构建训练集对象
+train_db = tf.data.Dataset.from_tensor_slices((x,y))
+train_db = train_db.shuffle(1000).map(preprocess).batch(128)
+# 构建测试集对象
+test_db = tf.data.Dataset.from_tensor_slices((x_test,y_test))
+test_db = test_db.map(preprocess).batch(128)
+# 从训练集中采样一个Batch，观察
+sample = next(iter(train_db))
+print('sample:', sample[0].shape, sample[1].shape,
+      tf.reduce_min(sample[0]), tf.reduce_max(sample[0]))
+
+
+
+# %%
+conv_layers = [ # 先创建包含多层的列表
+    # Conv-Conv-Pooling单元1
+    # 64个3x3卷积核, 输入输出同大小
+    layers.Conv2D(64, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(64, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    # 高宽减半
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # Conv-Conv-Pooling单元2,输出通道提升至128，高宽大小减半
+    layers.Conv2D(128, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(128, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # Conv-Conv-Pooling单元3,输出通道提升至256，高宽大小减半
+    layers.Conv2D(256, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(256, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # Conv-Conv-Pooling单元4,输出通道提升至512，高宽大小减半
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same'),
+
+    # Conv-Conv-Pooling单元5,输出通道提升至512，高宽大小减半
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.Conv2D(512, kernel_size=[3, 3], padding="same", activation=tf.nn.relu),
+    layers.MaxPool2D(pool_size=[2, 2], strides=2, padding='same')
+]
+# 利用前面创建的层列表构建网络容器
+conv_net = Sequential(conv_layers)
+
+
+# %%
+# 创建3层全连接层子网络
+fc_net = Sequential([
+    layers.Dense(256, activation=tf.nn.relu),
+    layers.Dense(128, activation=tf.nn.relu),
+    layers.Dense(100, activation=None),
+])
+
+
+# %%
+# build2个子网络，并打印网络参数信息
+conv_net.build(input_shape=[4, 32, 32, 3])
+fc_net.build(input_shape=[4, 512])
+conv_net.summary()
+fc_net.summary()
+
+
+# %%
+# 列表合并，合并2个子网络的参数
+variables = conv_net.trainable_variables + fc_net.trainable_variables
+# 对所有参数求梯度
+grads = tape.gradient(loss, variables)
+# 自动更新
+optimizer.apply_gradients(zip(grads, variables))
+
+
+# %%
+x = tf.random.normal([1,7,7,1]) # 模拟输入
+# 空洞卷积，1个3x3的卷积核
+layer = layers.Conv2D(1,kernel_size=3,strides=1,dilation_rate=2)
+out = layer(x) # 前向计算
+out.shape
+
+
+# %%
+# 创建X矩阵
+x = tf.range(25)+1
+# Reshape为合法维度的张量
+x = tf.reshape(x,[1,5,5,1])
+x = tf.cast(x, tf.float32)
+# 创建固定内容的卷积核矩阵
+w = tf.constant([[-1,2,-3.],[4,-5,6],[-7,8,-9]])
+# 调整为合法维度的张量
+w = tf.expand_dims(w,axis=2)
+w = tf.expand_dims(w,axis=3)
+# 进行普通卷积运算
+out = tf.nn.conv2d(x,w,strides=2,padding='VALID')
+out
+#%%
+# 普通卷积的输出作为转置卷积的输入，进行转置卷积运算
+xx = tf.nn.conv2d_transpose(out, w, strides=2, 
+    padding='VALID',
+    output_shape=[1,5,5,1])
+
+
+<tf.Tensor: id=117, shape=(5, 5), dtype=float32, numpy=
+array([[   67.,  -134.,   278.,  -154.,   231.],
+       [ -268.,   335.,  -710.,   385.,  -462.],
+       [  586.,  -770.,  1620.,  -870.,  1074.],
+       [ -468.,   585., -1210.,   635.,  -762.],
+       [  819.,  -936.,  1942., -1016.,  1143.]], dtype=float32)>
+
+
+# %%
+x = tf.random.normal([1,6,6,1])
+# 6x6的输入经过普通卷积
+out = tf.nn.conv2d(x,w,strides=2,padding='VALID')
+out
+<tf.Tensor: id=21, shape=(1, 2, 2, 1), dtype=float32, numpy=
+array([[[[ 20.438847 ],
+         [ 19.160788 ]],
+
+        [[  0.8098897],
+         [-28.30303  ]]]], dtype=float32)>
+# %%
+# 恢复出6x6大小
+xx = tf.nn.conv2d_transpose(out, w, strides=2, 
+    padding='VALID',
+    output_shape=[1,6,6,1])
+xx
+
+
+
+# %%
+# 创建转置卷积类
+layer = layers.Conv2DTranspose(1,kernel_size=3,strides=2,padding='VALID')
+xx2 = layer(out)
+xx2
+# %%
+class BasicBlock(layers.Layer):
+    # 残差模块类
+    def __init__(self, filter_num, stride=1):
+        super(BasicBlock, self).__init__()
+        # f(x)包含了2个普通卷积层，创建卷积层1
+        self.conv1 = layers.Conv2D(filter_num, (3, 3), strides=stride, padding='same')
+        self.bn1 = layers.BatchNormalization()
+        self.relu = layers.Activation('relu')
+        # 创建卷积层2
+        self.conv2 = layers.Conv2D(filter_num, (3, 3), strides=1, padding='same')
+        self.bn2 = layers.BatchNormalization()
+
+        if stride != 1: # 插入identity层
+            self.downsample = Sequential()
+            self.downsample.add(layers.Conv2D(filter_num, (1, 1), strides=stride))
+        else: # 否则，直接连接
+            self.downsample = lambda x:x
+
+
+    def call(self, inputs, training=None):
+        # 前向传播函数
+        out = self.conv1(inputs) # 通过第一个卷积层
+        out = self.bn1(out)
+        out = self.relu(out)
+        out = self.conv2(out) # 通过第二个卷积层
+        out = self.bn2(out)
+        # 输入通过identity()转换
+        identity = self.downsample(inputs)
+        # f(x)+x运算
+        output = layers.add([out, identity])
+        # 再通过激活函数并返回
+        output = tf.nn.relu(output)
+        return output

ch10/resnet.py

+import  tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers, Sequential
+
+
+
+class BasicBlock(layers.Layer):
+    # 残差模块
+    def __init__(self, filter_num, stride=1):
+        super(BasicBlock, self).__init__()
+        # 第一个卷积单元
+        self.conv1 = layers.Conv2D(filter_num, (3, 3), strides=stride, padding='same')
+        self.bn1 = layers.BatchNormalization()
+        self.relu = layers.Activation('relu')
+        # 第二个卷积单元
+        self.conv2 = layers.Conv2D(filter_num, (3, 3), strides=1, padding='same')
+        self.bn2 = layers.BatchNormalization()
+
+        if stride != 1:# 通过1x1卷积完成shape匹配
+            self.downsample = Sequential()
+            self.downsample.add(layers.Conv2D(filter_num, (1, 1), strides=stride))
+        else:# shape匹配，直接短接
+            self.downsample = lambda x:x
+
+    def call(self, inputs, training=None):
+
+        # [b, h, w, c]，通过第一个卷积单元
+        out = self.conv1(inputs)
+        out = self.bn1(out)
+        out = self.relu(out)
+        # 通过第二个卷积单元
+        out = self.conv2(out)
+        out = self.bn2(out)
+        # 通过identity模块
+        identity = self.downsample(inputs)
+        # 2条路径输出直接相加
+        output = layers.add([out, identity])
+        output = tf.nn.relu(output) # 激活函数
+
+        return output
+
+
+class ResNet(keras.Model):
+    # 通用的ResNet实现类
+    def __init__(self, layer_dims, num_classes=10): # [2, 2, 2, 2]
+        super(ResNet, self).__init__()
+        # 根网络，预处理
+        self.stem = Sequential([layers.Conv2D(64, (3, 3), strides=(1, 1)),
+                                layers.BatchNormalization(),
+                                layers.Activation('relu'),
+                                layers.MaxPool2D(pool_size=(2, 2), strides=(1, 1), padding='same')
+                                ])
+        # 堆叠4个Block，每个block包含了多个BasicBlock,设置步长不一样
+        self.layer1 = self.build_resblock(64,  layer_dims[0])
+        self.layer2 = self.build_resblock(128, layer_dims[1], stride=2)
+        self.layer3 = self.build_resblock(256, layer_dims[2], stride=2)
+        self.layer4 = self.build_resblock(512, layer_dims[3], stride=2)
+
+        # 通过Pooling层将高宽降低为1x1
+        self.avgpool = layers.GlobalAveragePooling2D()
+        # 最后连接一个全连接层分类
+        self.fc = layers.Dense(num_classes)
+
+    def call(self, inputs, training=None):
+        # 通过根网络
+        x = self.stem(inputs)
+        # 一次通过4个模块
+        x = self.layer1(x)
+        x = self.layer2(x)
+        x = self.layer3(x)
+        x = self.layer4(x)
+
+        # 通过池化层
+        x = self.avgpool(x)
+        # 通过全连接层
+        x = self.fc(x)
+
+        return x
+
+
+
+    def build_resblock(self, filter_num, blocks, stride=1):
+        # 辅助函数，堆叠filter_num个BasicBlock
+        res_blocks = Sequential()
+        # 只有第一个BasicBlock的步长可能不为1，实现下采样
+        res_blocks.add(BasicBlock(filter_num, stride))
+
+        for _ in range(1, blocks):#其他BasicBlock步长都为1
+            res_blocks.add(BasicBlock(filter_num, stride=1))
+
+        return res_blocks
+
+
+def resnet18():
+    # 通过调整模块内部BasicBlock的数量和配置实现不同的ResNet
+    return ResNet([2, 2, 2, 2])
+
+
+def resnet34():
+     # 通过调整模块内部BasicBlock的数量和配置实现不同的ResNet
+    return ResNet([3, 4, 6, 3])
\ No newline at end of file

ch10/resnet18_train.py

+import  tensorflow as tf
+from    tensorflow.keras import layers, optimizers, datasets, Sequential
+import  os
+from    resnet import resnet18
+
+os.environ['TF_CPP_MIN_LOG_LEVEL']='2'
+tf.random.set_seed(2345)
+
+
+
+
+
+def preprocess(x, y):
+    # 将数据映射到-1~1
+    x = 2*tf.cast(x, dtype=tf.float32) / 255. - 1
+    y = tf.cast(y, dtype=tf.int32) # 类型转换
+    return x,y
+
+
+(x,y), (x_test, y_test) = datasets.cifar10.load_data() # 加载数据集
+y = tf.squeeze(y, axis=1) # 删除不必要的维度
+y_test = tf.squeeze(y_test, axis=1) # 删除不必要的维度
+print(x.shape, y.shape, x_test.shape, y_test.shape)
+
+
+train_db = tf.data.Dataset.from_tensor_slices((x,y)) # 构建训练集
+# 随机打散，预处理，批量化
+train_db = train_db.shuffle(1000).map(preprocess).batch(512)
+
+test_db = tf.data.Dataset.from_tensor_slices((x_test,y_test)) #构建测试集
+# 随机打散，预处理，批量化
+test_db = test_db.map(preprocess).batch(512)
+# 采样一个样本
+sample = next(iter(train_db))
+print('sample:', sample[0].shape, sample[1].shape,
+      tf.reduce_min(sample[0]), tf.reduce_max(sample[0]))
+
+
+def main():
+
+    # [b, 32, 32, 3] => [b, 1, 1, 512]
+    model = resnet18() # ResNet18网络
+    model.build(input_shape=(None, 32, 32, 3))
+    model.summary() # 统计网络参数
+    optimizer = optimizers.Adam(lr=1e-4) # 构建优化器
+
+    for epoch in range(100): # 训练epoch
+
+        for step, (x,y) in enumerate(train_db):
+
+            with tf.GradientTape() as tape:
+                # [b, 32, 32, 3] => [b, 10],前向传播
+                logits = model(x)
+                # [b] => [b, 10],one-hot编码
+                y_onehot = tf.one_hot(y, depth=10)
+                # 计算交叉熵
+                loss = tf.losses.categorical_crossentropy(y_onehot, logits, from_logits=True)
+                loss = tf.reduce_mean(loss)
+            # 计算梯度信息
+            grads = tape.gradient(loss, model.trainable_variables)
+            # 更新网络参数
+            optimizer.apply_gradients(zip(grads, model.trainable_variables))
+
+            if step %50 == 0:
+                print(epoch, step, 'loss:', float(loss))
+
+
+
+        total_num = 0
+        total_correct = 0
+        for x,y in test_db:
+
+            logits = model(x)
+            prob = tf.nn.softmax(logits, axis=1)
+            pred = tf.argmax(prob, axis=1)
+            pred = tf.cast(pred, dtype=tf.int32)
+
+            correct = tf.cast(tf.equal(pred, y), dtype=tf.int32)
+            correct = tf.reduce_sum(correct)
+
+            total_num += x.shape[0]
+            total_correct += int(correct)
+
+        acc = total_correct / total_num
+        print(epoch, 'acc:', acc)
+
+
+
+if __name__ == '__main__':
+    main()

ch11/nb.py

+#%%
+import tensorflow as tf
+from tensorflow import keras
+from tensorflow.keras import layers
+
+import matplotlib.pyplot as plt
+
+#%%
+x = tf.range(10)
+x = tf.random.shuffle(x)
+# 创建共10个单词，每个单词用长度为4的向量表示的层
+net = layers.Embedding(10, 4)
+out = net(x)
+
+out
+#%%
+net.embeddings
+net.embeddings.trainable
+net.trainable = Flase
+#%%
+# 从预训练模型中加载词向量表
+embed_glove = load_embed('glove.6B.50d.txt')
+# 直接利用预训练的词向量表初始化Embedding层
+net.set_weights([embed_glove])
+#%%
+cell = layers.SimpleRNNCell(3)
+cell.build(input_shape=(None,4))
+cell.trainable_variables
+
+
+#%%
+# 初始化状态向量
+h0 = [tf.zeros([4, 64])]
+x = tf.random.normal([4, 80, 100])
+xt = x[:,0,:]
+# 构建输入特征f=100,序列长度s=80,状态长度=64的Cell
+cell = layers.SimpleRNNCell(64)
+out, h1 = cell(xt, h0) # 前向计算
+print(out.shape, h1[0].shape)
+print(id(out), id(h1[0])) 
+
+
+#%%
+h = h0
+# 在序列长度的维度解开输入，得到xt:[b,f]
+for xt in tf.unstack(x, axis=1):
+    out, h = cell(xt, h) # 前向计算
+# 最终输出可以聚合每个时间戳上的输出，也可以只取最后时间戳的输出
+out = out
+
+#%%
+x = tf.random.normal([4,80,100])
+xt = x[:,0,:] # 取第一个时间戳的输入x0
+# 构建2个Cell,先cell0,后cell1
+cell0 = layers.SimpleRNNCell(64)
+cell1 = layers.SimpleRNNCell(64)
+h0 = [tf.zeros([4,64])] # cell0的初始状态向量
+h1 = [tf.zeros([4,64])] # cell1的初始状态向量
+
+out0, h0 = cell0(xt, h0)
+out1, h1 = cell1(out0, h1)
+
+
+#%%
+for xt in tf.unstack(x, axis=1):
+    # xtw作为输入，输出为out0
+    out0, h0 = cell0(xt, h0)
+    # 上一个cell的输出out0作为本cell的输入
+    out1, h1 = cell1(out0, h1)
+
+
+#%%
+print(x.shape)
+# 保存上一层的所有时间戳上面的输出
+middle_sequences = []
+# 计算第一层的所有时间戳上的输出，并保存
+for xt in tf.unstack(x, axis=1):
+    out0, h0 = cell0(xt, h0)
+    middle_sequences.append(out0)
+# 计算第二层的所有时间戳上的输出
+# 如果不是末层，需要保存所有时间戳上面的输出
+for xt in middle_sequences:
+    out1, h1 = cell1(xt, h1)
+
+
+#%%
+layer = layers.SimpleRNN(64)
+x = tf.random.normal([4, 80, 100])
+out = layer(x)
+out.shape
+
+#%%
+layer = layers.SimpleRNN(64,return_sequences=True)
+out = layer(x) 
+out
+
+#%%
+net = keras.Sequential([ # 构建2层RNN网络
+# 除最末层外，都需要返回所有时间戳的输出
+layers.SimpleRNN(64, return_sequences=True),
+layers.SimpleRNN(64),
+])
+out = net(x)
+
+
+
+#%%
+W = tf.ones([2,2]) # 任意创建某矩阵
+eigenvalues = tf.linalg.eigh(W)[0] # 计算特征值
+eigenvalues
+#%%
+val = [W]
+for i in range(10): # 矩阵相乘n次方
+    val.append([val[-1]@W])
+# 计算L2范数
+norm = list(map(lambda x:tf.norm(x).numpy(),val))
+plt.plot(range(1,12),norm)
+plt.xlabel('n times')
+plt.ylabel('L2-norm')
+plt.savefig('w_n_times_1.svg')
+#%%
+W = tf.ones([2,2])*0.4 # 任意创建某矩阵
+eigenvalues = tf.linalg.eigh(W)[0] # 计算特征值
+print(eigenvalues)
+val = [W]
+for i in range(10):
+    val.append([val[-1]@W])
+norm = list(map(lambda x:tf.norm(x).numpy(),val))
+plt.plot(range(1,12),norm)
+plt.xlabel('n times')
+plt.ylabel('L2-norm')
+plt.savefig('w_n_times_0.svg')
+#%%
+a=tf.random.uniform([2,2])
+tf.clip_by_value(a,0.4,0.6) # 梯度值裁剪
+
+#%%
+
+
+
+
+#%%
+a=tf.random.uniform([2,2]) * 5
+# 按范数方式裁剪
+b = tf.clip_by_norm(a, 5)
+tf.norm(a),tf.norm(b)
+
+#%%
+w1=tf.random.normal([3,3]) # 创建梯度张量1
+w2=tf.random.normal([3,3]) # 创建梯度张量2
+# 计算global norm
+global_norm=tf.math.sqrt(tf.norm(w1)**2+tf.norm(w2)**2) 
+# 根据global norm和max norm=2裁剪
+(ww1,ww2),global_norm=tf.clip_by_global_norm([w1,w2],2)
+# 计算裁剪后的张量组的global norm
+global_norm2 = tf.math.sqrt(tf.norm(ww1)**2+tf.norm(ww2)**2)
+print(global_norm, global_norm2)
+
+#%%
+with tf.GradientTape() as tape:
+  logits = model(x) # 前向传播
+  loss = criteon(y, logits) # 误差计算
+# 计算梯度值
+grads = tape.gradient(loss, model.trainable_variables)
+grads, _ = tf.clip_by_global_norm(grads, 25) # 全局梯度裁剪
+# 利用裁剪后的梯度张量更新参数
+optimizer.apply_gradients(zip(grads, model.trainable_variables))
+
+#%%
+x = tf.random.normal([2,80,100])
+xt = x[:,0,:] # 得到一个时间戳的输入
+cell = layers.LSTMCell(64) # 创建Cell
+# 初始化状态和输出List,[h,c]
+state = [tf.zeros([2,64]),tf.zeros([2,64])]
+out, state = cell(xt, state) # 前向计算
+id(out),id(state[0]),id(state[1])
+
+
+#%%
+net = layers.LSTM(4)
+net.build(input_shape=(None,5,3))
+net.trainable_variables
+#%%
+
+net = layers.GRU(4)
+net.build(input_shape=(None,5,3))
+net.trainable_variables
+
+#%%
+# 初始化状态向量
+h = [tf.zeros([2,64])]
+cell = layers.GRUCell(64) # 新建GRU Cell
+for xt in tf.unstack(x, axis=1):
+    out, h = cell(xt, h)
+out.shape
+
+
+#%%

ch11/pretrained.py

+import os
+import sys
+import numpy as np
+import tensorflow as tf 
+from tensorflow import keras
+from tensorflow.keras import layers
+from tensorflow.keras.preprocessing.text import Tokenizer
+from tensorflow.keras.preprocessing.sequence import pad_sequences
+
+
+
+BASE_DIR = ''
+GLOVE_DIR = os.path.join(BASE_DIR, 'glove.6B')
+TEXT_DATA_DIR = os.path.join(BASE_DIR, '20_newsgroup')
+MAX_SEQUENCE_LENGTH = 1000
+MAX_NUM_WORDS = 20000
+EMBEDDING_DIM = 100
+VALIDATION_SPLIT = 0.2
+
+# first, build index mapping words in the embeddings set
+# to their embedding vector
+
+print('Indexing word vectors.')
+
+embeddings_index = {}
+with open(os.path.join(GLOVE_DIR, 'glove.6B.100d.txt')) as f:
+    for line in f:
+        values = line.split()
+        word = values[0]
+        coefs = np.asarray(values[1:], dtype='float32')
+        embeddings_index[word] = coefs
+
+print('Found %s word vectors.' % len(embeddings_index))
+
+# second, prepare text samples and their labels
+print('Processing text dataset')
+
+texts = []  # list of text samples
+labels_index = {}  # dictionary mapping label name to numeric id
+labels = []  # list of label ids
+for name in sorted(os.listdir(TEXT_DATA_DIR)):
+    path = os.path.join(TEXT_DATA_DIR, name)
+    if os.path.isdir(path):
+        label_id = len(labels_index)
+        labels_index[name] = label_id
+        for fname in sorted(os.listdir(path)):
+            if fname.isdigit():
+                fpath = os.path.join(path, fname)
+                args = {} if sys.version_info < (3,) else {'encoding': 'latin-1'}
+                with open(fpath, **args) as f:
+                    t = f.read()
+                    i = t.find('\n\n')  # skip header
+                    if 0 < i:
+                        t = t[i:]
+                    texts.append(t)
+                labels.append(label_id)
+
+print('Found %s texts.' % len(texts))
+
+# finally, vectorize the text samples into a 2D integer tensor
+tokenizer = Tokenizer(num_words=MAX_NUM_WORDS)
+tokenizer.fit_on_texts(texts)
+sequences = tokenizer.texts_to_sequences(texts)
+
+word_index = tokenizer.word_index
+print('Found %s unique tokens.' % len(word_index))
+
+data = pad_sequences(sequences, maxlen=MAX_SEQUENCE_LENGTH)
+
+labels = to_categorical(np.asarray(labels))
+print('Shape of data tensor:', data.shape)
+print('Shape of label tensor:', labels.shape)
+
+# split the data into a training set and a validation set
+indices = np.arange(data.shape[0])
+np.random.shuffle(indices)
+data = data[indices]
+labels = labels[indices]
+num_validation_samples = int(VALIDATION_SPLIT * data.shape[0])
+
+x_train = data[:-num_validation_samples]
+y_train = labels[:-num_validation_samples]
+x_val = data[-num_validation_samples:]
+y_val = labels[-num_validation_samples:]
+
+print('Preparing embedding matrix.')
+
+# prepare embedding matrix
+num_words = min(MAX_NUM_WORDS, len(word_index)) + 1
+embedding_matrix = np.zeros((num_words, EMBEDDING_DIM))
+for word, i in word_index.items():
+    if i > MAX_NUM_WORDS:
+        continue
+    embedding_vector = embeddings_index.get(word)
+    if embedding_vector is not None:
+        # words not found in embedding index will be all-zeros.
+        embedding_matrix[i] = embedding_vector
+
+# load pre-trained word embeddings into an Embedding layer
+# note that we set trainable = False so as to keep the embeddings fixed
+embedding_layer = Embedding(num_words,
+                            EMBEDDING_DIM,
+                            embeddings_initializer=Constant(embedding_matrix),
+                            input_length=MAX_SEQUENCE_LENGTH,
+                            trainable=False)
+
+print('Training model.')
+
+# train a 1D convnet with global maxpooling
+sequence_input = Input(shape=(MAX_SEQUENCE_LENGTH,), dtype='int32')
+embedded_sequences = embedding_layer(sequence_input)
+x = Conv1D(128, 5, activation='relu')(embedded_sequences)
+x = MaxPooling1D(5)(x)
+x = Conv1D(128, 5, activation='relu')(x)
+x = MaxPooling1D(5)(x)
+x = Conv1D(128, 5, activation='relu')(x)
+x = GlobalMaxPooling1D()(x)
+x = Dense(128, activation='relu')(x)
+preds = Dense(len(labels_index), activation='softmax')(x)
+
+model = Model(sequence_input, preds)
+model.compile(loss='categorical_crossentropy',
+              optimizer='rmsprop',
+              metrics=['acc'])
+
+model.fit(x_train, y_train,
+          batch_size=128,
+          epochs=10,
+          validation_data=(x_val, y_val))
\ No newline at end of file

ch11/sentiment_analysis_cell - GRU.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 128 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__()
+        # [b, 64]，构建Cell初始化状态向量，重复使用
+        self.state0 = [tf.zeros([batchsz, units])]
+        self.state1 = [tf.zeros([batchsz, units])]
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len)
+        # 构建2个Cell
+        self.rnn_cell0 = layers.GRUCell(units, dropout=0.5)
+        self.rnn_cell1 = layers.GRUCell(units, dropout=0.5)
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+        	layers.Dense(units),
+        	layers.Dropout(rate=0.5),
+        	layers.ReLU(),
+        	layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        state0 = self.state0
+        state1 = self.state1
+        for word in tf.unstack(x, axis=1): # word: [b, 100] 
+            out0, state0 = self.rnn_cell0(word, state0, training) 
+            out1, state1 = self.rnn_cell1(out0, state1, training)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(out1, training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 64 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.RMSprop(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()

ch11/sentiment_analysis_cell - LSTM.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 128 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__()
+        # [b, 64]，构建Cell初始化状态向量，重复使用
+        self.state0 = [tf.zeros([batchsz, units]),tf.zeros([batchsz, units])]
+        self.state1 = [tf.zeros([batchsz, units]),tf.zeros([batchsz, units])]
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len)
+        # 构建2个Cell
+        self.rnn_cell0 = layers.LSTMCell(units, dropout=0.5)
+        self.rnn_cell1 = layers.LSTMCell(units, dropout=0.5)
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+        	layers.Dense(units),
+        	layers.Dropout(rate=0.5),
+        	layers.ReLU(),
+        	layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        state0 = self.state0
+        state1 = self.state1
+        for word in tf.unstack(x, axis=1): # word: [b, 100] 
+            out0, state0 = self.rnn_cell0(word, state0, training) 
+            out1, state1 = self.rnn_cell1(out0, state1, training)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(out1,training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 64 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.RMSprop(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()

ch11/sentiment_analysis_cell.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 128 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__()
+        # [b, 64]，构建Cell初始化状态向量，重复使用
+        self.state0 = [tf.zeros([batchsz, units])]
+        self.state1 = [tf.zeros([batchsz, units])]
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len)
+        # 构建2个Cell
+        self.rnn_cell0 = layers.SimpleRNNCell(units, dropout=0.5)
+        self.rnn_cell1 = layers.SimpleRNNCell(units, dropout=0.5)
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+        	layers.Dense(units),
+        	layers.Dropout(rate=0.5),
+        	layers.ReLU(),
+        	layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        state0 = self.state0
+        state1 = self.state1
+        for word in tf.unstack(x, axis=1): # word: [b, 100] 
+            out0, state0 = self.rnn_cell0(word, state0, training) 
+            out1, state1 = self.rnn_cell1(out0, state1, training)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(out1, training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 64 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.RMSprop(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()

ch11/sentiment_analysis_layer - GRU.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 128 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__() 
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len)
+        # 构建RNN
+        self.rnn = keras.Sequential([
+            layers.GRU(units, dropout=0.5, return_sequences=True),
+            layers.GRU(units, dropout=0.5)
+        ])
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+        	layers.Dense(32),
+        	layers.Dropout(rate=0.5),
+        	layers.ReLU(),
+        	layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        x = self.rnn(x)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(x,training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 32 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.Adam(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()

ch11/sentiment_analysis_layer - LSTM - pretrained.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 128 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+print('Indexing word vectors.')
+embeddings_index = {}
+GLOVE_DIR = r'C:\Users\z390\Downloads\glove6b50dtxt'
+with open(os.path.join(GLOVE_DIR, 'glove.6B.100d.txt'),encoding='utf-8') as f:
+    for line in f:
+        values = line.split()
+        word = values[0]
+        coefs = np.asarray(values[1:], dtype='float32')
+        embeddings_index[word] = coefs
+
+print('Found %s word vectors.' % len(embeddings_index))
+#%%
+len(embeddings_index.keys())
+len(word_index.keys())
+#%%
+MAX_NUM_WORDS = total_words
+# prepare embedding matrix
+num_words = min(MAX_NUM_WORDS, len(word_index))
+embedding_matrix = np.zeros((num_words, embedding_len))
+applied_vec_count = 0
+for word, i in word_index.items():
+    if i >= MAX_NUM_WORDS:
+        continue
+    embedding_vector = embeddings_index.get(word)
+    # print(word,embedding_vector)
+    if embedding_vector is not None:
+        # words not found in embedding index will be all-zeros.
+        embedding_matrix[i] = embedding_vector
+        applied_vec_count += 1
+print(applied_vec_count, embedding_matrix.shape)
+
+#%%
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__() 
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len,
+                                          trainable=False)
+        self.embedding.build(input_shape=(None,max_review_len))
+        # self.embedding.set_weights([embedding_matrix])
+        # 构建RNN
+        self.rnn = keras.Sequential([
+            layers.LSTM(units, dropout=0.5, return_sequences=True),
+            layers.LSTM(units, dropout=0.5)
+        ])
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+            layers.Dense(32),
+            layers.Dropout(rate=0.5),
+            layers.ReLU(),
+            layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        x = self.rnn(x)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(x,training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 512 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.Adam(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()
+
+
+#%%

ch11/sentiment_analysis_layer - LSTM.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 128 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__() 
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len)
+        # 构建RNN
+        self.rnn = keras.Sequential([
+            layers.LSTM(units, dropout=0.5, return_sequences=True),
+            layers.LSTM(units, dropout=0.5)
+        ])
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+        	layers.Dense(32),
+        	layers.Dropout(rate=0.5),
+        	layers.ReLU(),
+        	layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        x = self.rnn(x)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(x,training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 32 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.Adam(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()

ch11/sentiment_analysis_layer.py

+#%%
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers, losses, optimizers, Sequential
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+batchsz = 512 # 批量大小
+total_words = 10000 # 词汇表大小N_vocab
+max_review_len = 80 # 句子最大长度s，大于的句子部分将截断，小于的将填充
+embedding_len = 100 # 词向量特征长度f
+# 加载IMDB数据集，此处的数据采用数字编码，一个数字代表一个单词
+(x_train, y_train), (x_test, y_test) = keras.datasets.imdb.load_data(num_words=total_words)
+print(x_train.shape, len(x_train[0]), y_train.shape)
+print(x_test.shape, len(x_test[0]), y_test.shape)
+#%%
+x_train[0]
+#%%
+# 数字编码表
+word_index = keras.datasets.imdb.get_word_index()
+# for k,v in word_index.items():
+#     print(k,v)
+#%%
+word_index = {k:(v+3) for k,v in word_index.items()}
+word_index["<PAD>"] = 0
+word_index["<START>"] = 1
+word_index["<UNK>"] = 2  # unknown
+word_index["<UNUSED>"] = 3
+# 翻转编码表
+reverse_word_index = dict([(value, key) for (key, value) in word_index.items()])
+
+def decode_review(text):
+    return ' '.join([reverse_word_index.get(i, '?') for i in text])
+
+decode_review(x_train[8])
+
+#%%
+
+# x_train:[b, 80]
+# x_test: [b, 80]
+# 截断和填充句子，使得等长，此处长句子保留句子后面的部分，短句子在前面填充
+x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=max_review_len)
+x_test = keras.preprocessing.sequence.pad_sequences(x_test, maxlen=max_review_len)
+# 构建数据集，打散，批量，并丢掉最后一个不够batchsz的batch
+db_train = tf.data.Dataset.from_tensor_slices((x_train, y_train))
+db_train = db_train.shuffle(1000).batch(batchsz, drop_remainder=True)
+db_test = tf.data.Dataset.from_tensor_slices((x_test, y_test))
+db_test = db_test.batch(batchsz, drop_remainder=True)
+print('x_train shape:', x_train.shape, tf.reduce_max(y_train), tf.reduce_min(y_train))
+print('x_test shape:', x_test.shape)
+
+#%%
+
+class MyRNN(keras.Model):
+    # Cell方式构建多层网络
+    def __init__(self, units):
+        super(MyRNN, self).__init__() 
+        # 词向量编码 [b, 80] => [b, 80, 100]
+        self.embedding = layers.Embedding(total_words, embedding_len,
+                                          input_length=max_review_len)
+        # 构建RNN
+        self.rnn = keras.Sequential([
+            layers.SimpleRNN(units, dropout=0.5, return_sequences=True),
+            layers.SimpleRNN(units, dropout=0.5)
+        ])
+        # 构建分类网络，用于将CELL的输出特征进行分类，2分类
+        # [b, 80, 100] => [b, 64] => [b, 1]
+        self.outlayer = Sequential([
+        	layers.Dense(32),
+        	layers.Dropout(rate=0.5),
+        	layers.ReLU(),
+        	layers.Dense(1)])
+
+    def call(self, inputs, training=None):
+        x = inputs # [b, 80]
+        # embedding: [b, 80] => [b, 80, 100]
+        x = self.embedding(x)
+        # rnn cell compute,[b, 80, 100] => [b, 64]
+        x = self.rnn(x)
+        # 末层最后一个输出作为分类网络的输入: [b, 64] => [b, 1]
+        x = self.outlayer(x,training)
+        # p(y is pos|x)
+        prob = tf.sigmoid(x)
+
+        return prob
+
+def main():
+    units = 64 # RNN状态向量长度f
+    epochs = 50 # 训练epochs
+
+    model = MyRNN(units)
+    # 装配
+    model.compile(optimizer = optimizers.Adam(0.001),
+                  loss = losses.BinaryCrossentropy(),
+                  metrics=['accuracy'])
+    # 训练和验证
+    model.fit(db_train, epochs=epochs, validation_data=db_test)
+    # 测试
+    model.evaluate(db_test)
+
+
+if __name__ == '__main__':
+    main()

ch12/autoencoder.py

+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import Sequential, layers
+from    PIL import Image
+from    matplotlib import pyplot as plt
+
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+def save_images(imgs, name):
+    new_im = Image.new('L', (280, 280))
+
+    index = 0
+    for i in range(0, 280, 28):
+        for j in range(0, 280, 28):
+            im = imgs[index]
+            im = Image.fromarray(im, mode='L')
+            new_im.paste(im, (i, j))
+            index += 1
+
+    new_im.save(name)
+
+
+h_dim = 20
+batchsz = 512
+lr = 1e-3
+
+
+(x_train, y_train), (x_test, y_test) = keras.datasets.fashion_mnist.load_data()
+x_train, x_test = x_train.astype(np.float32) / 255., x_test.astype(np.float32) / 255.
+# we do not need label
+train_db = tf.data.Dataset.from_tensor_slices(x_train)
+train_db = train_db.shuffle(batchsz * 5).batch(batchsz)
+test_db = tf.data.Dataset.from_tensor_slices(x_test)
+test_db = test_db.batch(batchsz)
+
+print(x_train.shape, y_train.shape)
+print(x_test.shape, y_test.shape)
+
+
+
+class AE(keras.Model):
+
+    def __init__(self):
+        super(AE, self).__init__()
+
+        # Encoders
+        self.encoder = Sequential([
+            layers.Dense(256, activation=tf.nn.relu),
+            layers.Dense(128, activation=tf.nn.relu),
+            layers.Dense(h_dim)
+        ])
+
+        # Decoders
+        self.decoder = Sequential([
+            layers.Dense(128, activation=tf.nn.relu),
+            layers.Dense(256, activation=tf.nn.relu),
+            layers.Dense(784)
+        ])
+
+
+    def call(self, inputs, training=None):
+        # [b, 784] => [b, 10]
+        h = self.encoder(inputs)
+        # [b, 10] => [b, 784]
+        x_hat = self.decoder(h)
+
+        return x_hat
+
+
+
+model = AE()
+model.build(input_shape=(None, 784))
+model.summary()
+
+optimizer = tf.optimizers.Adam(lr=lr)
+
+for epoch in range(100):
+
+    for step, x in enumerate(train_db):
+
+        #[b, 28, 28] => [b, 784]
+        x = tf.reshape(x, [-1, 784])
+
+        with tf.GradientTape() as tape:
+            x_rec_logits = model(x)
+
+            rec_loss = tf.losses.binary_crossentropy(x, x_rec_logits, from_logits=True)
+            rec_loss = tf.reduce_mean(rec_loss)
+
+        grads = tape.gradient(rec_loss, model.trainable_variables)
+        optimizer.apply_gradients(zip(grads, model.trainable_variables))
+
+
+        if step % 100 ==0:
+            print(epoch, step, float(rec_loss))
+
+
+        # evaluation
+        x = next(iter(test_db))
+        logits = model(tf.reshape(x, [-1, 784]))
+        x_hat = tf.sigmoid(logits)
+        # [b, 784] => [b, 28, 28]
+        x_hat = tf.reshape(x_hat, [-1, 28, 28])
+
+        # [b, 28, 28] => [2b, 28, 28]
+        x_concat = tf.concat([x, x_hat], axis=0)
+        x_concat = x_hat
+        x_concat = x_concat.numpy() * 255.
+        x_concat = x_concat.astype(np.uint8)
+        save_images(x_concat, 'ae_images/rec_epoch_%d.png'%epoch)

ch12/vae.py

+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import Sequential, layers
+from    PIL import Image
+from    matplotlib import pyplot as plt
+
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+def save_images(imgs, name):
+    new_im = Image.new('L', (280, 280))
+
+    index = 0
+    for i in range(0, 280, 28):
+        for j in range(0, 280, 28):
+            im = imgs[index]
+            im = Image.fromarray(im, mode='L')
+            new_im.paste(im, (i, j))
+            index += 1
+
+    new_im.save(name)
+
+
+h_dim = 20
+batchsz = 512
+lr = 1e-3
+
+
+(x_train, y_train), (x_test, y_test) = keras.datasets.fashion_mnist.load_data()
+x_train, x_test = x_train.astype(np.float32) / 255., x_test.astype(np.float32) / 255.
+# we do not need label
+train_db = tf.data.Dataset.from_tensor_slices(x_train)
+train_db = train_db.shuffle(batchsz * 5).batch(batchsz)
+test_db = tf.data.Dataset.from_tensor_slices(x_test)
+test_db = test_db.batch(batchsz)
+
+print(x_train.shape, y_train.shape)
+print(x_test.shape, y_test.shape)
+
+z_dim = 10
+
+class VAE(keras.Model):
+
+    def __init__(self):
+        super(VAE, self).__init__()
+
+        # Encoder
+        self.fc1 = layers.Dense(128)
+        self.fc2 = layers.Dense(z_dim) # get mean prediction
+        self.fc3 = layers.Dense(z_dim)
+
+        # Decoder
+        self.fc4 = layers.Dense(128)
+        self.fc5 = layers.Dense(784)
+
+    def encoder(self, x):
+
+        h = tf.nn.relu(self.fc1(x))
+        # get mean
+        mu = self.fc2(h)
+        # get variance
+        log_var = self.fc3(h)
+
+        return mu, log_var
+
+    def decoder(self, z):
+
+        out = tf.nn.relu(self.fc4(z))
+        out = self.fc5(out)
+
+        return out
+
+    def reparameterize(self, mu, log_var):
+
+        eps = tf.random.normal(log_var.shape)
+
+        std = tf.exp(log_var*0.5)
+
+        z = mu + std * eps
+        return z
+
+    def call(self, inputs, training=None):
+
+        # [b, 784] => [b, z_dim], [b, z_dim]
+        mu, log_var = self.encoder(inputs)
+        # reparameterization trick
+        z = self.reparameterize(mu, log_var)
+
+        x_hat = self.decoder(z)
+
+        return x_hat, mu, log_var
+
+
+model = VAE()
+model.build(input_shape=(4, 784))
+optimizer = tf.optimizers.Adam(lr)
+
+for epoch in range(1000):
+
+    for step, x in enumerate(train_db):
+
+        x = tf.reshape(x, [-1, 784])
+
+        with tf.GradientTape() as tape:
+            x_rec_logits, mu, log_var = model(x)
+
+            rec_loss = tf.nn.sigmoid_cross_entropy_with_logits(labels=x, logits=x_rec_logits)
+            rec_loss = tf.reduce_sum(rec_loss) / x.shape[0]
+
+            # compute kl divergence (mu, var) ~ N (0, 1)
+            # https://stats.stackexchange.com/questions/7440/kl-divergence-between-two-univariate-gaussians
+            kl_div = -0.5 * (log_var + 1 - mu**2 - tf.exp(log_var))
+            kl_div = tf.reduce_sum(kl_div) / x.shape[0]
+
+            loss = rec_loss + 1. * kl_div
+
+        grads = tape.gradient(loss, model.trainable_variables)
+        optimizer.apply_gradients(zip(grads, model.trainable_variables))
+
+
+        if step % 100 == 0:
+            print(epoch, step, 'kl div:', float(kl_div), 'rec loss:', float(rec_loss))
+
+
+    # evaluation
+    z = tf.random.normal((batchsz, z_dim))
+    logits = model.decoder(z)
+    x_hat = tf.sigmoid(logits)
+    x_hat = tf.reshape(x_hat, [-1, 28, 28]).numpy() *255.
+    x_hat = x_hat.astype(np.uint8)
+    save_images(x_hat, 'vae_images/sampled_epoch%d.png'%epoch)
+
+    x = next(iter(test_db))
+    x = tf.reshape(x, [-1, 784])
+    x_hat_logits, _, _ = model(x)
+    x_hat = tf.sigmoid(x_hat_logits)
+    x_hat = tf.reshape(x_hat, [-1, 28, 28]).numpy() *255.
+    x_hat = x_hat.astype(np.uint8)
+    save_images(x_hat, 'vae_images/rec_epoch%d.png'%epoch)
+

ch13/dataset.py

+import multiprocessing
+
+import tensorflow as tf
+
+
+def make_anime_dataset(img_paths, batch_size, resize=64, drop_remainder=True, shuffle=True, repeat=1):
+
+    # @tf.function
+    def _map_fn(img):
+        img = tf.image.resize(img, [resize, resize])
+        # img = tf.image.random_crop(img,[resize, resize])
+        # img = tf.image.random_flip_left_right(img)
+        # img = tf.image.random_flip_up_down(img)
+        img = tf.clip_by_value(img, 0, 255)
+        img = img / 127.5 - 1 #-1~1
+        return img
+
+    dataset = disk_image_batch_dataset(img_paths,
+                                          batch_size,
+                                          drop_remainder=drop_remainder,
+                                          map_fn=_map_fn,
+                                          shuffle=shuffle,
+                                          repeat=repeat)
+    img_shape = (resize, resize, 3)
+    len_dataset = len(img_paths) // batch_size
+
+    return dataset, img_shape, len_dataset
+
+
+def batch_dataset(dataset,
+                  batch_size,
+                  drop_remainder=True,
+                  n_prefetch_batch=1,
+                  filter_fn=None,
+                  map_fn=None,
+                  n_map_threads=None,
+                  filter_after_map=False,
+                  shuffle=True,
+                  shuffle_buffer_size=None,
+                  repeat=None):
+    # set defaults
+    if n_map_threads is None:
+        n_map_threads = multiprocessing.cpu_count()
+    if shuffle and shuffle_buffer_size is None:
+        shuffle_buffer_size = max(batch_size * 128, 2048)  # set the minimum buffer size as 2048
+
+    # [*] it is efficient to conduct `shuffle` before `map`/`filter` because `map`/`filter` is sometimes costly
+    if shuffle:
+        dataset = dataset.shuffle(shuffle_buffer_size)
+
+    if not filter_after_map:
+        if filter_fn:
+            dataset = dataset.filter(filter_fn)
+
+        if map_fn:
+            dataset = dataset.map(map_fn, num_parallel_calls=n_map_threads)
+
+    else:  # [*] this is slower
+        if map_fn:
+            dataset = dataset.map(map_fn, num_parallel_calls=n_map_threads)
+
+        if filter_fn:
+            dataset = dataset.filter(filter_fn)
+
+    dataset = dataset.batch(batch_size, drop_remainder=drop_remainder)
+
+    dataset = dataset.repeat(repeat).prefetch(n_prefetch_batch)
+
+    return dataset
+
+
+def memory_data_batch_dataset(memory_data,
+                              batch_size,
+                              drop_remainder=True,
+                              n_prefetch_batch=1,
+                              filter_fn=None,
+                              map_fn=None,
+                              n_map_threads=None,
+                              filter_after_map=False,
+                              shuffle=True,
+                              shuffle_buffer_size=None,
+                              repeat=None):
+    """Batch dataset of memory data.
+
+    Parameters
+    ----------
+    memory_data : nested structure of tensors/ndarrays/lists
+
+    """
+    dataset = tf.data.Dataset.from_tensor_slices(memory_data)
+    dataset = batch_dataset(dataset,
+                            batch_size,
+                            drop_remainder=drop_remainder,
+                            n_prefetch_batch=n_prefetch_batch,
+                            filter_fn=filter_fn,
+                            map_fn=map_fn,
+                            n_map_threads=n_map_threads,
+                            filter_after_map=filter_after_map,
+                            shuffle=shuffle,
+                            shuffle_buffer_size=shuffle_buffer_size,
+                            repeat=repeat)
+    return dataset
+
+
+def disk_image_batch_dataset(img_paths,
+                             batch_size,
+                             labels=None,
+                             drop_remainder=True,
+                             n_prefetch_batch=1,
+                             filter_fn=None,
+                             map_fn=None,
+                             n_map_threads=None,
+                             filter_after_map=False,
+                             shuffle=True,
+                             shuffle_buffer_size=None,
+                             repeat=None):
+    """Batch dataset of disk image for PNG and JPEG.
+
+    Parameters
+    ----------
+        img_paths : 1d-tensor/ndarray/list of str
+        labels : nested structure of tensors/ndarrays/lists
+
+    """
+    if labels is None:
+        memory_data = img_paths
+    else:
+        memory_data = (img_paths, labels)
+
+    def parse_fn(path, *label):
+        img = tf.io.read_file(path)
+        img = tf.image.decode_jpeg(img, channels=3)  # fix channels to 3
+        return (img,) + label
+
+    if map_fn:  # fuse `map_fn` and `parse_fn`
+        def map_fn_(*args):
+            return map_fn(*parse_fn(*args))
+    else:
+        map_fn_ = parse_fn
+
+    dataset = memory_data_batch_dataset(memory_data,
+                                        batch_size,
+                                        drop_remainder=drop_remainder,
+                                        n_prefetch_batch=n_prefetch_batch,
+                                        filter_fn=filter_fn,
+                                        map_fn=map_fn_,
+                                        n_map_threads=n_map_threads,
+                                        filter_after_map=filter_after_map,
+                                        shuffle=shuffle,
+                                        shuffle_buffer_size=shuffle_buffer_size,
+                                        repeat=repeat)
+
+    return dataset

ch13/gan.py

+import  tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers
+
+
+class Generator(keras.Model):
+    # 生成器网络
+    def __init__(self):
+        super(Generator, self).__init__()
+        filter = 64
+        # 转置卷积层1,输出channel为filter*8,核大小4,步长1,不使用padding,不使用偏置
+        self.conv1 = layers.Conv2DTranspose(filter*8, 4,1, 'valid', use_bias=False)
+        self.bn1 = layers.BatchNormalization()
+        # 转置卷积层2
+        self.conv2 = layers.Conv2DTranspose(filter*4, 4,2, 'same', use_bias=False)
+        self.bn2 = layers.BatchNormalization()
+        # 转置卷积层3
+        self.conv3 = layers.Conv2DTranspose(filter*2, 4,2, 'same', use_bias=False)
+        self.bn3 = layers.BatchNormalization()
+        # 转置卷积层4
+        self.conv4 = layers.Conv2DTranspose(filter*1, 4,2, 'same', use_bias=False)
+        self.bn4 = layers.BatchNormalization()
+        # 转置卷积层5
+        self.conv5 = layers.Conv2DTranspose(3, 4,2, 'same', use_bias=False)
+
+    def call(self, inputs, training=None):
+        x = inputs # [z, 100]
+        # Reshape乘4D张量，方便后续转置卷积运算:(b, 1, 1, 100)
+        x = tf.reshape(x, (x.shape[0], 1, 1, x.shape[1]))
+        x = tf.nn.relu(x) # 激活函数
+        # 转置卷积-BN-激活函数:(b, 4, 4, 512)
+        x = tf.nn.relu(self.bn1(self.conv1(x), training=training))
+        # 转置卷积-BN-激活函数:(b, 8, 8, 256)
+        x = tf.nn.relu(self.bn2(self.conv2(x), training=training))
+        # 转置卷积-BN-激活函数:(b, 16, 16, 128)
+        x = tf.nn.relu(self.bn3(self.conv3(x), training=training))
+        # 转置卷积-BN-激活函数:(b, 32, 32, 64)
+        x = tf.nn.relu(self.bn4(self.conv4(x), training=training))
+        # 转置卷积-激活函数:(b, 64, 64, 3)
+        x = self.conv5(x)
+        x = tf.tanh(x) # 输出x范围-1~1,与预处理一致
+
+        return x
+
+
+class Discriminator(keras.Model):
+    # 判别器
+    def __init__(self):
+        super(Discriminator, self).__init__()
+        filter = 64
+        # 卷积层
+        self.conv1 = layers.Conv2D(filter, 4, 2, 'valid', use_bias=False)
+        self.bn1 = layers.BatchNormalization()
+        # 卷积层
+        self.conv2 = layers.Conv2D(filter*2, 4, 2, 'valid', use_bias=False)
+        self.bn2 = layers.BatchNormalization()
+        # 卷积层
+        self.conv3 = layers.Conv2D(filter*4, 4, 2, 'valid', use_bias=False)
+        self.bn3 = layers.BatchNormalization()
+        # 卷积层
+        self.conv4 = layers.Conv2D(filter*8, 3, 1, 'valid', use_bias=False)
+        self.bn4 = layers.BatchNormalization()
+        # 卷积层
+        self.conv5 = layers.Conv2D(filter*16, 3, 1, 'valid', use_bias=False)
+        self.bn5 = layers.BatchNormalization()
+        # 全局池化层
+        self.pool = layers.GlobalAveragePooling2D()
+        # 特征打平
+        self.flatten = layers.Flatten()
+        # 2分类全连接层
+        self.fc = layers.Dense(1)
+
+
+    def call(self, inputs, training=None):
+        # 卷积-BN-激活函数:(4, 31, 31, 64)
+        x = tf.nn.leaky_relu(self.bn1(self.conv1(inputs), training=training))
+        # 卷积-BN-激活函数:(4, 14, 14, 128)
+        x = tf.nn.leaky_relu(self.bn2(self.conv2(x), training=training))
+        # 卷积-BN-激活函数:(4, 6, 6, 256)
+        x = tf.nn.leaky_relu(self.bn3(self.conv3(x), training=training))
+        # 卷积-BN-激活函数:(4, 4, 4, 512)
+        x = tf.nn.leaky_relu(self.bn4(self.conv4(x), training=training))
+        # 卷积-BN-激活函数:(4, 2, 2, 1024)
+        x = tf.nn.leaky_relu(self.bn5(self.conv5(x), training=training))
+        # 卷积-BN-激活函数:(4, 1024)
+        x = self.pool(x)
+        # 打平
+        x = self.flatten(x)
+        # 输出，[b, 1024] => [b, 1]
+        logits = self.fc(x)
+
+        return logits
+
+def main():
+
+    d = Discriminator()
+    g = Generator()
+
+
+    x = tf.random.normal([2, 64, 64, 3])
+    z = tf.random.normal([2, 100])
+
+    prob = d(x)
+    print(prob)
+    x_hat = g(z)
+    print(x_hat.shape)
+
+
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file

ch13/gan_train.py

+import  os
+import  numpy as np
+import  tensorflow as tf
+from    tensorflow import keras
+from    scipy.misc import toimage
+import  glob
+from    gan import Generator, Discriminator
+
+from    dataset import make_anime_dataset
+
+
+def save_result(val_out, val_block_size, image_path, color_mode):
+    def preprocess(img):
+        img = ((img + 1.0) * 127.5).astype(np.uint8)
+        # img = img.astype(np.uint8)
+        return img
+
+    preprocesed = preprocess(val_out)
+    final_image = np.array([])
+    single_row = np.array([])
+    for b in range(val_out.shape[0]):
+        # concat image into a row
+        if single_row.size == 0:
+            single_row = preprocesed[b, :, :, :]
+        else:
+            single_row = np.concatenate((single_row, preprocesed[b, :, :, :]), axis=1)
+
+        # concat image row to final_image
+        if (b+1) % val_block_size == 0:
+            if final_image.size == 0:
+                final_image = single_row
+            else:
+                final_image = np.concatenate((final_image, single_row), axis=0)
+
+            # reset single row
+            single_row = np.array([])
+
+    if final_image.shape[2] == 1:
+        final_image = np.squeeze(final_image, axis=2)
+    toimage(final_image).save(image_path)
+
+
+def celoss_ones(logits):
+    # 计算属于与标签为1的交叉熵
+    y = tf.ones_like(logits)
+    loss = keras.losses.binary_crossentropy(y, logits, from_logits=True)
+    return tf.reduce_mean(loss)
+
+
+def celoss_zeros(logits):
+    # 计算属于与便签为0的交叉熵
+    y = tf.zeros_like(logits)
+    loss = keras.losses.binary_crossentropy(y, logits, from_logits=True)
+    return tf.reduce_mean(loss)
+
+def d_loss_fn(generator, discriminator, batch_z, batch_x, is_training):
+    # 计算判别器的误差函数
+    # 采样生成图片
+    fake_image = generator(batch_z, is_training)
+    # 判定生成图片
+    d_fake_logits = discriminator(fake_image, is_training)
+    # 判定真实图片
+    d_real_logits = discriminator(batch_x, is_training)
+    # 真实图片与1之间的误差
+    d_loss_real = celoss_ones(d_real_logits)
+    # 生成图片与0之间的误差
+    d_loss_fake = celoss_zeros(d_fake_logits)
+    # 合并误差
+    loss = d_loss_fake + d_loss_real
+
+    return loss
+
+
+def g_loss_fn(generator, discriminator, batch_z, is_training):
+    # 采样生成图片
+    fake_image = generator(batch_z, is_training)
+    # 在训练生成网络时，需要迫使生成图片判定为真
+    d_fake_logits = discriminator(fake_image, is_training)
+    # 计算生成图片与1之间的误差
+    loss = celoss_ones(d_fake_logits)
+
+    return loss
+
+def main():
+
+    tf.random.set_seed(3333)
+    np.random.seed(3333)
+    os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+    assert tf.__version__.startswith('2.')
+
+
+    z_dim = 100 # 隐藏向量z的长度
+    epochs = 3000000 # 训练步数
+    batch_size = 64 # batch size
+    learning_rate = 0.0002
+    is_training = True
+
+    # 获取数据集路径
+    # C:\Users\z390\Downloads\anime-faces
+    # r'C:\Users\z390\Downloads\faces\*.jpg'
+    img_path = glob.glob(r'C:\Users\z390\Downloads\anime-faces\*\*.jpg') + \
+        glob.glob(r'C:\Users\z390\Downloads\anime-faces\*\*.png')
+    # img_path = glob.glob(r'C:\Users\z390\Downloads\getchu_aligned_with_label\GetChu_aligned2\*.jpg')
+    # img_path.extend(img_path2)
+    print('images num:', len(img_path))
+    # 构建数据集对象
+    dataset, img_shape, _ = make_anime_dataset(img_path, batch_size, resize=64)
+    print(dataset, img_shape)
+    sample = next(iter(dataset)) # 采样
+    print(sample.shape, tf.reduce_max(sample).numpy(),
+          tf.reduce_min(sample).numpy())
+    dataset = dataset.repeat(100) # 重复循环
+    db_iter = iter(dataset)
+
+
+    generator = Generator() # 创建生成器
+    generator.build(input_shape = (4, z_dim))
+    discriminator = Discriminator() # 创建判别器
+    discriminator.build(input_shape=(4, 64, 64, 3))
+    # 分别为生成器和判别器创建优化器
+    g_optimizer = keras.optimizers.Adam(learning_rate=learning_rate, beta_1=0.5)
+    d_optimizer = keras.optimizers.Adam(learning_rate=learning_rate, beta_1=0.5)
+
+    generator.load_weights('generator.ckpt')
+    discriminator.load_weights('discriminator.ckpt')
+    print('Loaded chpt!!')
+
+    d_losses, g_losses = [],[]
+    for epoch in range(epochs): # 训练epochs次
+        # 1. 训练判别器
+        for _ in range(1):
+            # 采样隐藏向量
+            batch_z = tf.random.normal([batch_size, z_dim])
+            batch_x = next(db_iter) # 采样真实图片
+            # 判别器前向计算
+            with tf.GradientTape() as tape:
+                d_loss = d_loss_fn(generator, discriminator, batch_z, batch_x, is_training)
+            grads = tape.gradient(d_loss, discriminator.trainable_variables)
+            d_optimizer.apply_gradients(zip(grads, discriminator.trainable_variables))
+        # 2. 训练生成器
+        # 采样隐藏向量
+        batch_z = tf.random.normal([batch_size, z_dim])
+        batch_x = next(db_iter) # 采样真实图片
+        # 生成器前向计算
+        with tf.GradientTape() as tape:
+            g_loss = g_loss_fn(generator, discriminator, batch_z, is_training)
+        grads = tape.gradient(g_loss, generator.trainable_variables)
+        g_optimizer.apply_gradients(zip(grads, generator.trainable_variables))
+
+        if epoch % 100 == 0:
+            print(epoch, 'd-loss:',float(d_loss), 'g-loss:', float(g_loss))
+            # 可视化
+            z = tf.random.normal([100, z_dim])
+            fake_image = generator(z, training=False)
+            img_path = os.path.join('gan_images', 'gan-%d.png'%epoch)
+            save_result(fake_image.numpy(), 10, img_path, color_mode='P')
+
+            d_losses.append(float(d_loss))
+            g_losses.append(float(g_loss))
+
+            if epoch % 10000 == 1:
+                # print(d_losses)
+                # print(g_losses)
+                generator.save_weights('generator.ckpt')
+                discriminator.save_weights('discriminator.ckpt')
+
+            
+
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file

ch14/REINFORCE_tf.py

+import 	gym,os
+import  numpy as np
+import  matplotlib
+from 	matplotlib import pyplot as plt
+# Default parameters for plots
+matplotlib.rcParams['font.size'] = 18
+matplotlib.rcParams['figure.titlesize'] = 18
+matplotlib.rcParams['figure.figsize'] = [9, 7]
+matplotlib.rcParams['font.family'] = ['KaiTi']
+matplotlib.rcParams['axes.unicode_minus']=False 
+
+import 	tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers,optimizers,losses
+from    PIL import Image
+env = gym.make('CartPole-v1')  # 创建游戏环境
+env.seed(2333)
+tf.random.set_seed(2333)
+np.random.seed(2333)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+learning_rate = 0.0002
+gamma         = 0.98
+
+class Policy(keras.Model):
+    # 策略网络，生成动作的概率分布
+    def __init__(self):
+        super(Policy, self).__init__()
+        self.data = [] # 存储轨迹
+        # 输入为长度为4的向量，输出为左、右2个动作
+        self.fc1 = layers.Dense(128, kernel_initializer='he_normal')
+        self.fc2 = layers.Dense(2, kernel_initializer='he_normal')
+        # 网络优化器
+        self.optimizer = optimizers.Adam(lr=learning_rate)
+
+    def call(self, inputs, training=None):
+        # 状态输入s的shape为向量：[4]
+        x = tf.nn.relu(self.fc1(inputs))
+        x = tf.nn.softmax(self.fc2(x), axis=1)
+        return x
+
+    def put_data(self, item):
+        # 记录r,log_P(a|s)
+        self.data.append(item)
+
+    def train_net(self, tape):
+        # 计算梯度并更新策略网络参数。tape为梯度记录器
+        R = 0 # 终结状态的初始回报为0
+        for r, log_prob in self.data[::-1]:#逆序取
+            R = r + gamma * R # 计算每个时间戳上的回报
+            # 每个时间戳都计算一次梯度
+            # grad_R=-log_P*R*grad_theta
+            loss = -log_prob * R
+            with tape.stop_recording():
+                # 优化策略网络
+                grads = tape.gradient(loss, self.trainable_variables)
+                # print(grads)
+                self.optimizer.apply_gradients(zip(grads, self.trainable_variables))
+        self.data = [] # 清空轨迹
+
+def main():
+    pi = Policy() # 创建策略网络
+    pi(tf.random.normal((4,4)))
+    pi.summary()
+    score = 0.0 # 计分
+    print_interval = 20 # 打印间隔
+    returns = []
+
+    for n_epi in range(400):
+        s = env.reset() # 回到游戏初始状态，返回s0
+        with tf.GradientTape(persistent=True) as tape:
+            for t in range(501): # CartPole-v1 forced to terminates at 500 step.
+                # 送入状态向量，获取策略
+                s = tf.constant(s,dtype=tf.float32)
+                # s: [4] => [1,4]
+                s = tf.expand_dims(s, axis=0)
+                prob = pi(s) # 动作分布:[1,2]
+                # 从类别分布中采样1个动作, shape: [1]
+                a = tf.random.categorical(tf.math.log(prob), 1)[0]
+                a = int(a) # Tensor转数字
+                s_prime, r, done, info = env.step(a)
+                # 记录动作a和动作产生的奖励r
+                # prob shape:[1,2]
+                pi.put_data((r, tf.math.log(prob[0][a])))
+                s = s_prime # 刷新状态
+                score += r # 累积奖励
+
+                if n_epi >1000:
+                    env.render()
+                    # im = Image.fromarray(s)
+                    # im.save("res/%d.jpg" % info['frames'][0])
+
+                if done:  # 当前episode终止
+                    break
+            # episode终止后，训练一次网络
+            pi.train_net(tape)
+        del tape
+
+        if n_epi%print_interval==0 and n_epi!=0:
+            returns.append(score/print_interval)
+            print(f"# of episode :{n_epi}, avg score : {score/print_interval}")
+            score = 0.0
+    env.close() # 关闭环境
+
+    plt.plot(np.arange(len(returns))*print_interval, returns)
+    plt.plot(np.arange(len(returns))*print_interval, returns, 's')
+    plt.xlabel('回合数')
+    plt.ylabel('总回报')
+    plt.savefig('reinforce-tf-cartpole.svg')
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file

ch14/a3c_tf_cartpole.py

+import  matplotlib
+from    matplotlib import pyplot as plt
+matplotlib.rcParams['font.size'] = 18
+matplotlib.rcParams['figure.titlesize'] = 18
+matplotlib.rcParams['figure.figsize'] = [9, 7]
+matplotlib.rcParams['font.family'] = ['KaiTi']
+matplotlib.rcParams['axes.unicode_minus']=False
+
+plt.figure()
+
+import os
+os.environ["CUDA_VISIBLE_DEVICES"] = ""
+import  threading
+import  gym
+import  multiprocessing
+import  numpy as np
+from    queue import Queue
+import  matplotlib.pyplot as plt
+
+import  tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers,optimizers,losses
+
+
+
+tf.random.set_seed(1231)
+np.random.seed(1231)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+class ActorCritic(keras.Model):
+    # Actor-Critic模型
+    def __init__(self, state_size, action_size):
+        super(ActorCritic, self).__init__()
+        self.state_size = state_size # 状态向量长度
+        self.action_size = action_size # 动作数量
+        # 策略网络Actor
+        self.dense1 = layers.Dense(128, activation='relu')
+        self.policy_logits = layers.Dense(action_size)
+        # V网络Critic
+        self.dense2 = layers.Dense(128, activation='relu')
+        self.values = layers.Dense(1)
+
+    def call(self, inputs):
+        # 获得策略分布Pi(a|s)
+        x = self.dense1(inputs)
+        logits = self.policy_logits(x)
+        # 获得v(s)
+        v = self.dense2(inputs)
+        values = self.values(v)
+        return logits, values
+
+
+def record(episode,
+           episode_reward,
+           worker_idx,
+           global_ep_reward,
+           result_queue,
+           total_loss,
+           num_steps):
+    # 统计工具函数
+    if global_ep_reward == 0:
+        global_ep_reward = episode_reward
+    else:
+        global_ep_reward = global_ep_reward * 0.99 + episode_reward * 0.01
+    print(
+        f"{episode} | "
+        f"Average Reward: {int(global_ep_reward)} | "
+        f"Episode Reward: {int(episode_reward)} | "
+        f"Loss: {int(total_loss / float(num_steps) * 1000) / 1000} | "
+        f"Steps: {num_steps} | "
+        f"Worker: {worker_idx}"
+    )
+    result_queue.put(global_ep_reward) # 保存回报，传给主线程
+    return global_ep_reward
+
+class Memory:
+    def __init__(self):
+        self.states = []
+        self.actions = []
+        self.rewards = []
+
+    def store(self, state, action, reward):
+        self.states.append(state)
+        self.actions.append(action)
+        self.rewards.append(reward)
+
+    def clear(self):
+        self.states = []
+        self.actions = []
+        self.rewards = []
+
+class Agent:
+    # 智能体，包含了中央参数网络server
+    def __init__(self):
+        # server优化器，client不需要，直接从server拉取参数
+        self.opt = optimizers.Adam(1e-3)
+        # 中央模型，类似于参数服务器
+        self.server = ActorCritic(4, 2) # 状态向量，动作数量
+        self.server(tf.random.normal((2, 4)))
+    def train(self):
+        res_queue = Queue() # 共享队列
+        # 创建各个交互环境
+        workers = [Worker(self.server, self.opt, res_queue, i)
+                   for i in range(multiprocessing.cpu_count())]
+        for i, worker in enumerate(workers):
+            print("Starting worker {}".format(i))
+            worker.start()
+        # 统计并绘制总回报曲线
+        returns = []
+        while True:
+            reward = res_queue.get()
+            if reward is not None:
+                returns.append(reward)
+            else: # 结束标志
+                break
+        [w.join() for w in workers] # 等待线程退出 
+
+        print(returns)
+        plt.figure()
+        plt.plot(np.arange(len(returns)), returns)
+        # plt.plot(np.arange(len(moving_average_rewards)), np.array(moving_average_rewards), 's')
+        plt.xlabel('回合数')
+        plt.ylabel('总回报')
+        plt.savefig('a3c-tf-cartpole.svg')
+
+
+class Worker(threading.Thread): 
+    def __init__(self,  server, opt, result_queue, idx):
+        super(Worker, self).__init__()
+        self.result_queue = result_queue # 共享队列
+        self.server = server # 中央模型
+        self.opt = opt # 中央优化器
+        self.client = ActorCritic(4, 2) # 线程私有网络
+        self.worker_idx = idx # 线程id
+        self.env = gym.make('CartPole-v1').unwrapped
+        self.ep_loss = 0.0
+
+    def run(self): 
+        mem = Memory() # 每个worker自己维护一个memory
+        for epi_counter in range(500): # 未达到最大回合数
+            current_state = self.env.reset() # 复位client游戏状态
+            mem.clear()
+            ep_reward = 0.
+            ep_steps = 0  
+            done = False
+            while not done:
+                # 获得Pi(a|s),未经softmax
+                logits, _ = self.client(tf.constant(current_state[None, :],
+                                         dtype=tf.float32))
+                probs = tf.nn.softmax(logits)
+                # 随机采样动作
+                action = np.random.choice(2, p=probs.numpy()[0])
+                new_state, reward, done, _ = self.env.step(action) # 交互 
+                ep_reward += reward # 累加奖励
+                mem.store(current_state, action, reward) # 记录
+                ep_steps += 1 # 计算回合步数
+                current_state = new_state # 刷新状态 
+
+                if ep_steps >= 500 or done: # 最长步数500
+                    # 计算当前client上的误差
+                    with tf.GradientTape() as tape:
+                        total_loss = self.compute_loss(done, new_state, mem) 
+                    # 计算误差
+                    grads = tape.gradient(total_loss, self.client.trainable_weights)
+                    # 梯度提交到server，在server上更新梯度
+                    self.opt.apply_gradients(zip(grads,
+                                                 self.server.trainable_weights))
+                    # 从server拉取最新的梯度
+                    self.client.set_weights(self.server.get_weights())
+                    mem.clear() # 清空Memory 
+                    # 统计此回合回报
+                    self.result_queue.put(ep_reward)
+                    print(self.worker_idx, ep_reward)
+                    break
+        self.result_queue.put(None) # 结束线程
+
+    def compute_loss(self,
+                     done,
+                     new_state,
+                     memory,
+                     gamma=0.99):
+        if done:
+            reward_sum = 0. # 终止状态的v(终止)=0
+        else:
+            reward_sum = self.client(tf.constant(new_state[None, :],
+                                     dtype=tf.float32))[-1].numpy()[0]
+        # 统计折扣回报
+        discounted_rewards = []
+        for reward in memory.rewards[::-1]:  # reverse buffer r
+            reward_sum = reward + gamma * reward_sum
+            discounted_rewards.append(reward_sum)
+        discounted_rewards.reverse()
+        # 获取状态的Pi(a|s)和v(s)
+        logits, values = self.client(tf.constant(np.vstack(memory.states),
+                                 dtype=tf.float32))
+        # 计算advantage = R() - v(s)
+        advantage = tf.constant(np.array(discounted_rewards)[:, None],
+                                         dtype=tf.float32) - values
+        # Critic网络损失
+        value_loss = advantage ** 2
+        # 策略损失
+        policy = tf.nn.softmax(logits)
+        policy_loss = tf.nn.sparse_softmax_cross_entropy_with_logits(
+                        labels=memory.actions, logits=logits)
+        # 计算策略网络损失时，并不会计算V网络
+        policy_loss = policy_loss * tf.stop_gradient(advantage)
+        # Entropy Bonus
+        entropy = tf.nn.softmax_cross_entropy_with_logits(labels=policy,
+                                                          logits=logits)
+        policy_loss = policy_loss - 0.01 * entropy
+        # 聚合各个误差
+        total_loss = tf.reduce_mean((0.5 * value_loss + policy_loss))
+        return total_loss
+
+
+if __name__ == '__main__':
+    master = Agent()
+    master.train()

ch14/dqn_tf.py

+import collections
+import random
+import gym,os
+import  numpy as np
+import  tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers,optimizers,losses
+
+env = gym.make('CartPole-v1')  # 创建游戏环境
+env.seed(1234)
+tf.random.set_seed(1234)
+np.random.seed(1234)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+# Hyperparameters
+learning_rate = 0.0002
+gamma = 0.99
+buffer_limit = 50000
+batch_size = 32
+
+
+class ReplayBuffer():
+    # 经验回放池
+    def __init__(self):
+        # 双向队列
+        self.buffer = collections.deque(maxlen=buffer_limit)
+
+    def put(self, transition):
+        self.buffer.append(transition)
+
+    def sample(self, n):
+        # 从回放池采样n个5元组
+        mini_batch = random.sample(self.buffer, n)
+        s_lst, a_lst, r_lst, s_prime_lst, done_mask_lst = [], [], [], [], []
+        # 按类别进行整理
+        for transition in mini_batch:
+            s, a, r, s_prime, done_mask = transition
+            s_lst.append(s)
+            a_lst.append([a])
+            r_lst.append([r])
+            s_prime_lst.append(s_prime)
+            done_mask_lst.append([done_mask])
+        # 转换成Tensor
+        return tf.constant(s_lst, dtype=tf.float32),\
+                      tf.constant(a_lst, dtype=tf.int32), \
+                      tf.constant(r_lst, dtype=tf.float32), \
+                      tf.constant(s_prime_lst, dtype=tf.float32), \
+                      tf.constant(done_mask_lst, dtype=tf.float32)
+
+
+    def size(self):
+        return len(self.buffer)
+
+
+class Qnet(keras.Model):
+    def __init__(self):
+        # 创建Q网络，输入为状态向量，输出为动作的Q值
+        super(Qnet, self).__init__()
+        self.fc1 = layers.Dense(256, kernel_initializer='he_normal')
+        self.fc2 = layers.Dense(256, kernel_initializer='he_normal')
+        self.fc3 = layers.Dense(2, kernel_initializer='he_normal')
+
+    def call(self, x, training=None):
+        x = tf.nn.relu(self.fc1(x))
+        x = tf.nn.relu(self.fc2(x))
+        x = self.fc3(x)
+        return x
+
+    def sample_action(self, s, epsilon):
+        # 送入状态向量，获取策略: [4]
+        s = tf.constant(s, dtype=tf.float32)
+        # s: [4] => [1,4]
+        s = tf.expand_dims(s, axis=0)
+        out = self(s)[0]
+        coin = random.random()
+        # 策略改进：e-贪心方式
+        if coin < epsilon:
+            # epsilon大的概率随机选取
+            return random.randint(0, 1)
+        else:  # 选择Q值最大的动作
+            return int(tf.argmax(out))
+
+
+def train(q, q_target, memory, optimizer):
+    # 通过Q网络和影子网络来构造贝尔曼方程的误差，
+    # 并只更新Q网络，影子网络的更新会滞后Q网络
+    huber = losses.Huber()
+    for i in range(10):  # 训练10次
+        # 从缓冲池采样
+        s, a, r, s_prime, done_mask = memory.sample(batch_size)
+        with tf.GradientTape() as tape:
+            # s: [b, 4]
+            q_out = q(s)  # 得到Q(s,a)的分布
+            # 由于TF的gather_nd与pytorch的gather功能不一样，需要构造
+            # gather_nd需要的坐标参数，indices:[b, 2]
+            # pi_a = pi.gather(1, a) # pytorch只需要一行即可实现
+            indices = tf.expand_dims(tf.range(a.shape[0]), axis=1)
+            indices = tf.concat([indices, a], axis=1)
+            q_a = tf.gather_nd(q_out, indices) # 动作的概率值, [b]
+            q_a = tf.expand_dims(q_a, axis=1) # [b]=> [b,1]
+            # 得到Q(s',a)的最大值，它来自影子网络！ [b,4]=>[b,2]=>[b,1]
+            max_q_prime = tf.reduce_max(q_target(s_prime),axis=1,keepdims=True)
+            # 构造Q(s,a_t)的目标值，来自贝尔曼方程
+            target = r + gamma * max_q_prime * done_mask
+            # 计算Q(s,a_t)与目标值的误差
+            loss = huber(q_a, target)
+        # 更新网络，使得Q(s,a_t)估计符合贝尔曼方程
+        grads = tape.gradient(loss, q.trainable_variables)
+        # for p in grads:
+        #     print(tf.norm(p))
+        # print(grads)
+        optimizer.apply_gradients(zip(grads, q.trainable_variables))
+
+
+def main():
+    env = gym.make('CartPole-v1')  # 创建环境
+    q = Qnet()  # 创建Q网络
+    q_target = Qnet()  # 创建影子网络
+    q.build(input_shape=(2,4))
+    q_target.build(input_shape=(2,4))
+    for src, dest in zip(q.variables, q_target.variables):
+        dest.assign(src) # 影子网络权值来自Q
+    memory = ReplayBuffer()  # 创建回放池
+
+    print_interval = 20
+    score = 0.0
+    optimizer = optimizers.Adam(lr=learning_rate)
+
+    for n_epi in range(10000):  # 训练次数
+        # epsilon概率也会8%到1%衰减，越到后面越使用Q值最大的动作
+        epsilon = max(0.01, 0.08 - 0.01 * (n_epi / 200))
+        s = env.reset()  # 复位环境
+        for t in range(600):  # 一个回合最大时间戳
+            # if n_epi>1000:
+            #     env.render()
+            # 根据当前Q网络提取策略，并改进策略
+            a = q.sample_action(s, epsilon)
+            # 使用改进的策略与环境交互
+            s_prime, r, done, info = env.step(a)
+            done_mask = 0.0 if done else 1.0  # 结束标志掩码
+            # 保存5元组
+            memory.put((s, a, r / 100.0, s_prime, done_mask))
+            s = s_prime  # 刷新状态
+            score += r  # 记录总回报
+            if done:  # 回合结束
+                break
+
+        if memory.size() > 2000:  # 缓冲池只有大于2000就可以训练
+            train(q, q_target, memory, optimizer)
+
+        if n_epi % print_interval == 0 and n_epi != 0:
+            for src, dest in zip(q.variables, q_target.variables):
+                dest.assign(src)  # 影子网络权值来自Q
+            print("# of episode :{}, avg score : {:.1f}, buffer size : {}, " \
+                  "epsilon : {:.1f}%" \
+                  .format(n_epi, score / print_interval, memory.size(), epsilon * 100))
+            score = 0.0
+    env.close()
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file

ch14/ppo_tf_cartpole.py

+import  matplotlib
+from 	matplotlib import pyplot as plt
+matplotlib.rcParams['font.size'] = 18
+matplotlib.rcParams['figure.titlesize'] = 18
+matplotlib.rcParams['figure.figsize'] = [9, 7]
+matplotlib.rcParams['font.family'] = ['KaiTi']
+matplotlib.rcParams['axes.unicode_minus']=False
+
+plt.figure()
+
+import  gym,os
+import  numpy as np
+import  tensorflow as tf
+from    tensorflow import keras
+from    tensorflow.keras import layers,optimizers,losses
+from    collections import namedtuple
+from    torch.utils.data import SubsetRandomSampler,BatchSampler
+
+env = gym.make('CartPole-v1')  # 创建游戏环境
+env.seed(2222)
+tf.random.set_seed(2222)
+np.random.seed(2222)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+
+gamma = 0.98 # 激励衰减因子
+epsilon = 0.2 # PPO误差超参数0.8~1.2
+batch_size = 32 # batch size
+
+
+# 创建游戏环境
+env = gym.make('CartPole-v0').unwrapped
+Transition = namedtuple('Transition', ['state', 'action', 'a_log_prob', 'reward', 'next_state'])
+
+
+class Actor(keras.Model):
+    def __init__(self):
+        super(Actor, self).__init__()
+        # 策略网络，也叫Actor网络，输出为概率分布pi(a|s)
+        self.fc1 = layers.Dense(100, kernel_initializer='he_normal')
+        self.fc2 = layers.Dense(2, kernel_initializer='he_normal')
+
+    def call(self, inputs):
+        x = tf.nn.relu(self.fc1(inputs))
+        x = self.fc2(x)
+        x = tf.nn.softmax(x, axis=1) # 转换成概率
+        return x
+
+class Critic(keras.Model):
+    def __init__(self):
+        super(Critic, self).__init__()
+        # 偏置b的估值网络，也叫Critic网络，输出为v(s)
+        self.fc1 = layers.Dense(100, kernel_initializer='he_normal')
+        self.fc2 = layers.Dense(1, kernel_initializer='he_normal')
+
+    def call(self, inputs):
+        x = tf.nn.relu(self.fc1(inputs))
+        x = self.fc2(x)
+        return x
+
+
+
+
+class PPO():
+    # PPO算法主体
+    def __init__(self):
+        super(PPO, self).__init__()
+        self.actor = Actor() # 创建Actor网络
+        self.critic = Critic() # 创建Critic网络
+        self.buffer = [] # 数据缓冲池
+        self.actor_optimizer = optimizers.Adam(1e-3) # Actor优化器
+        self.critic_optimizer = optimizers.Adam(3e-3) # Critic优化器
+
+    def select_action(self, s):
+        # 送入状态向量，获取策略: [4]
+        s = tf.constant(s, dtype=tf.float32)
+        # s: [4] => [1,4]
+        s = tf.expand_dims(s, axis=0)
+        # 获取策略分布: [1, 2]
+        prob = self.actor(s)
+        # 从类别分布中采样1个动作, shape: [1]
+        a = tf.random.categorical(tf.math.log(prob), 1)[0]
+        a = int(a)  # Tensor转数字
+        return a, float(prob[0][a]) # 返回动作及其概率
+
+    def get_value(self, s):
+        # 送入状态向量，获取策略: [4]
+        s = tf.constant(s, dtype=tf.float32)
+        # s: [4] => [1,4]
+        s = tf.expand_dims(s, axis=0)
+        # 获取策略分布: [1, 2]
+        v = self.critic(s)[0]
+        return float(v) # 返回v(s)
+
+    def store_transition(self, transition):
+        # 存储采样数据
+        self.buffer.append(transition)
+
+    def optimize(self):
+        # 优化网络主函数
+        # 从缓存中取出样本数据，转换成Tensor
+        state = tf.constant([t.state for t in self.buffer], dtype=tf.float32)
+        action = tf.constant([t.action for t in self.buffer], dtype=tf.int32)
+        action = tf.reshape(action,[-1,1])
+        reward = [t.reward for t in self.buffer]
+        old_action_log_prob = tf.constant([t.a_log_prob for t in self.buffer], dtype=tf.float32)
+        old_action_log_prob = tf.reshape(old_action_log_prob, [-1,1])
+        # 通过MC方法循环计算R(st)
+        R = 0
+        Rs = []
+        for r in reward[::-1]:
+            R = r + gamma * R
+            Rs.insert(0, R)
+        Rs = tf.constant(Rs, dtype=tf.float32)
+        # 对缓冲池数据大致迭代10遍
+        for _ in range(round(10*len(self.buffer)/batch_size)):
+            # 随机从缓冲池采样batch size大小样本
+            index = np.random.choice(np.arange(len(self.buffer)), batch_size, replace=False)
+            # 构建梯度跟踪环境
+            with tf.GradientTape() as tape1, tf.GradientTape() as tape2:
+                # 取出R(st)，[b,1]
+                v_target = tf.expand_dims(tf.gather(Rs, index, axis=0), axis=1)
+                # 计算v(s)预测值，也就是偏置b，我们后面会介绍为什么写成v
+                v = self.critic(tf.gather(state, index, axis=0))
+                delta = v_target - v # 计算优势值
+                advantage = tf.stop_gradient(delta) # 断开梯度连接 
+                # 由于TF的gather_nd与pytorch的gather功能不一样，需要构造
+                # gather_nd需要的坐标参数，indices:[b, 2]
+                # pi_a = pi.gather(1, a) # pytorch只需要一行即可实现
+                a = tf.gather(action, index, axis=0) # 取出batch的动作at
+                # batch的动作分布pi(a|st)
+                pi = self.actor(tf.gather(state, index, axis=0)) 
+                indices = tf.expand_dims(tf.range(a.shape[0]), axis=1)
+                indices = tf.concat([indices, a], axis=1)
+                pi_a = tf.gather_nd(pi, indices)  # 动作的概率值pi(at|st), [b]
+                pi_a = tf.expand_dims(pi_a, axis=1)  # [b]=> [b,1] 
+                # 重要性采样
+                ratio = (pi_a / tf.gather(old_action_log_prob, index, axis=0))
+                surr1 = ratio * advantage
+                surr2 = tf.clip_by_value(ratio, 1 - epsilon, 1 + epsilon) * advantage
+                # PPO误差函数
+                policy_loss = -tf.reduce_mean(tf.minimum(surr1, surr2))
+                # 对于偏置v来说，希望与MC估计的R(st)越接近越好
+                value_loss = losses.MSE(v_target, v)
+            # 优化策略网络
+            grads = tape1.gradient(policy_loss, self.actor.trainable_variables)
+            self.actor_optimizer.apply_gradients(zip(grads, self.actor.trainable_variables))
+            # 优化偏置值网络
+            grads = tape2.gradient(value_loss, self.critic.trainable_variables)
+            self.critic_optimizer.apply_gradients(zip(grads, self.critic.trainable_variables))
+
+        self.buffer = []  # 清空已训练数据
+
+
+def main():
+    agent = PPO()
+    returns = [] # 统计总回报
+    total = 0 # 一段时间内平均回报
+    for i_epoch in range(500): # 训练回合数
+        state = env.reset() # 复位环境
+        for t in range(500): # 最多考虑500步
+            # 通过最新策略与环境交互
+            action, action_prob = agent.select_action(state)
+            next_state, reward, done, _ = env.step(action)
+            # 构建样本并存储
+            trans = Transition(state, action, action_prob, reward, next_state)
+            agent.store_transition(trans)
+            state = next_state # 刷新状态
+            total += reward # 累积激励
+            if done: # 合适的时间点训练网络
+                if len(agent.buffer) >= batch_size:
+                    agent.optimize() # 训练网络
+                break
+
+        if i_epoch % 20 == 0: # 每20个回合统计一次平均回报
+            returns.append(total/20)
+            total = 0
+            print(i_epoch, returns[-1])
+
+    print(np.array(returns))
+    plt.figure()
+    plt.plot(np.arange(len(returns))*20, np.array(returns))
+    plt.plot(np.arange(len(returns))*20, np.array(returns), 's')
+    plt.xlabel('回合数')
+    plt.ylabel('总回报')
+    plt.savefig('ppo-tf-cartpole.svg')
+
+
+if __name__ == '__main__':
+    main()
+    print("end")
\ No newline at end of file

ch15/pokemon.py

+import  os, glob
+import  random, csv
+import tensorflow as tf
+
+
+
+def load_csv(root, filename, name2label):
+    # 从csv文件返回images,labels列表
+    # root:数据集根目录，filename:csv文件名， name2label:类别名编码表
+    if not os.path.exists(os.path.join(root, filename)):
+        # 如果csv文件不存在，则创建
+        images = []
+        for name in name2label.keys(): # 遍历所有子目录，获得所有的图片
+            # 只考虑后缀为png,jpg,jpeg的图片：'pokemon\\mewtwo\\00001.png
+            images += glob.glob(os.path.join(root, name, '*.png'))
+            images += glob.glob(os.path.join(root, name, '*.jpg'))
+            images += glob.glob(os.path.join(root, name, '*.jpeg'))
+        # 打印数据集信息：1167, 'pokemon\\bulbasaur\\00000000.png'
+        print(len(images), images)
+        random.shuffle(images) # 随机打散顺序
+        # 创建csv文件，并存储图片路径及其label信息
+        with open(os.path.join(root, filename), mode='w', newline='') as f:
+            writer = csv.writer(f)
+            for img in images:  # 'pokemon\\bulbasaur\\00000000.png'
+                name = img.split(os.sep)[-2]
+                label = name2label[name]
+                # 'pokemon\\bulbasaur\\00000000.png', 0
+                writer.writerow([img, label])
+            print('written into csv file:', filename)
+
+    # 此时已经有csv文件，直接读取
+    images, labels = [], []
+    with open(os.path.join(root, filename)) as f:
+        reader = csv.reader(f)
+        for row in reader:
+            # 'pokemon\\bulbasaur\\00000000.png', 0
+            img, label = row
+            label = int(label)
+            images.append(img)
+            labels.append(label) 
+    # 返回图片路径list和标签list
+    return images, labels
+
+
+def load_pokemon(root, mode='train'):
+    # 创建数字编码表
+    name2label = {}  # "sq...":0
+    # 遍历根目录下的子文件夹，并排序，保证映射关系固定
+    for name in sorted(os.listdir(os.path.join(root))):
+        # 跳过非文件夹
+        if not os.path.isdir(os.path.join(root, name)):
+            continue
+        # 给每个类别编码一个数字
+        name2label[name] = len(name2label.keys())
+
+    # 读取Label信息
+    # [file1,file2,], [3,1]
+    images, labels = load_csv(root, 'images.csv', name2label)
+
+    if mode == 'train':  # 60%
+        images = images[:int(0.6 * len(images))]
+        labels = labels[:int(0.6 * len(labels))]
+    elif mode == 'val':  # 20% = 60%->80%
+        images = images[int(0.6 * len(images)):int(0.8 * len(images))]
+        labels = labels[int(0.6 * len(labels)):int(0.8 * len(labels))]
+    else:  # 20% = 80%->100%
+        images = images[int(0.8 * len(images)):]
+        labels = labels[int(0.8 * len(labels)):]
+
+    return images, labels, name2label
+
+# 这里的mean和std根据真实的数据计算获得，比如ImageNet
+img_mean = tf.constant([0.485, 0.456, 0.406])
+img_std = tf.constant([0.229, 0.224, 0.225])
+def normalize(x, mean=img_mean, std=img_std):
+    # 标准化
+    # x: [224, 224, 3]
+    # mean: [224, 224, 3], std: [3]
+    x = (x - mean)/std
+    return x
+
+def denormalize(x, mean=img_mean, std=img_std):
+    # 标准化的逆过程
+    x = x * std + mean
+    return x
+
+def preprocess(x,y):
+    # x: 图片的路径List，y：图片的数字编码List
+    x = tf.io.read_file(x) # 根据路径读取图片
+    x = tf.image.decode_jpeg(x, channels=3) # 图片解码
+    x = tf.image.resize(x, [244, 244]) # 图片缩放
+
+    # 数据增强
+    # x = tf.image.random_flip_up_down(x)
+    x= tf.image.random_flip_left_right(x) # 左右镜像
+    x = tf.image.random_crop(x, [224, 224, 3]) # 随机裁剪
+    # 转换成张量
+    # x: [0,255]=> 0~1
+    x = tf.cast(x, dtype=tf.float32) / 255.
+    # 0~1 => D(0,1)
+    x = normalize(x) # 标准化
+    y = tf.convert_to_tensor(y) # 转换成张量
+
+    return x, y
+
+
+def main():
+    import  time
+
+
+
+    # 加载pokemon数据集，指定加载训练集
+    images, labels, table = load_pokemon('pokemon', 'train')
+    print('images:', len(images), images)
+    print('labels:', len(labels), labels)
+    print('table:', table)
+
+    # images: string path
+    # labels: number
+    db = tf.data.Dataset.from_tensor_slices((images, labels))
+    db = db.shuffle(1000).map(preprocess).batch(32)
+
+    # 创建TensorBoard对象
+    writter = tf.summary.create_file_writer('logs')
+    for step, (x,y) in enumerate(db):
+        # x: [32, 224, 224, 3]
+        # y: [32]
+        with writter.as_default():
+            x = denormalize(x) # 反向normalize，方便可视化
+            # 写入图片数据
+            tf.summary.image('img',x,step=step,max_outputs=9)
+            time.sleep(5)
+
+
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file

ch15/resnet.py

+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers
+
+
+
+tf.random.set_seed(22)
+np.random.seed(22)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+
+class ResnetBlock(keras.Model):
+
+    def __init__(self, channels, strides=1):
+        super(ResnetBlock, self).__init__()
+
+        self.channels = channels
+        self.strides = strides
+
+        self.conv1 = layers.Conv2D(channels, 3, strides=strides,
+                                   padding=[[0,0],[1,1],[1,1],[0,0]])
+        self.bn1 = keras.layers.BatchNormalization()
+        self.conv2 = layers.Conv2D(channels, 3, strides=1,
+                                   padding=[[0,0],[1,1],[1,1],[0,0]])
+        self.bn2 = keras.layers.BatchNormalization()
+
+        if strides!=1:
+            self.down_conv = layers.Conv2D(channels, 1, strides=strides, padding='valid')
+            self.down_bn = tf.keras.layers.BatchNormalization()
+
+    def call(self, inputs, training=None):
+        residual = inputs
+
+        x = self.conv1(inputs)
+        x = tf.nn.relu(x)
+        x = self.bn1(x, training=training)
+        x = self.conv2(x)
+        x = tf.nn.relu(x)
+        x = self.bn2(x, training=training)
+
+        # 残差连接
+        if self.strides!=1:
+            residual = self.down_conv(inputs)
+            residual = tf.nn.relu(residual)
+            residual = self.down_bn(residual, training=training)
+
+        x = x + residual
+        x = tf.nn.relu(x)
+        return x
+
+
+class ResNet(keras.Model):
+
+    def __init__(self, num_classes, initial_filters=16, **kwargs):
+        super(ResNet, self).__init__(**kwargs)
+
+        self.stem = layers.Conv2D(initial_filters, 3, strides=3, padding='valid')
+
+        self.blocks = keras.models.Sequential([
+            ResnetBlock(initial_filters * 2, strides=3),
+            ResnetBlock(initial_filters * 2, strides=1),
+            # layers.Dropout(rate=0.5),
+
+            ResnetBlock(initial_filters * 4, strides=3),
+            ResnetBlock(initial_filters * 4, strides=1),
+
+            ResnetBlock(initial_filters * 8, strides=2),
+            ResnetBlock(initial_filters * 8, strides=1),
+
+            ResnetBlock(initial_filters * 16, strides=2),
+            ResnetBlock(initial_filters * 16, strides=1),
+        ])
+
+        self.final_bn = layers.BatchNormalization()
+        self.avg_pool = layers.GlobalMaxPool2D()
+        self.fc = layers.Dense(num_classes)
+
+    def call(self, inputs, training=None):
+        # print('x:',inputs.shape)
+        out = self.stem(inputs)
+        out = tf.nn.relu(out)
+
+        # print('stem:',out.shape)
+
+        out = self.blocks(out, training=training)
+        # print('res:',out.shape)
+
+        out = self.final_bn(out, training=training)
+        # out = tf.nn.relu(out)
+
+        out = self.avg_pool(out)
+
+        # print('avg_pool:',out.shape)
+        out = self.fc(out)
+
+        # print('out:',out.shape)
+
+        return out
+
+
+
+def main():
+    num_classes = 5
+
+    resnet18 = ResNet(5)
+    resnet18.build(input_shape=(4,224,224,3))
+    resnet18.summary()
+
+
+
+
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file

ch15/train_scratch.py

+import  matplotlib
+from    matplotlib import pyplot as plt
+matplotlib.rcParams['font.size'] = 18
+matplotlib.rcParams['figure.titlesize'] = 18
+matplotlib.rcParams['figure.figsize'] = [9, 7]
+matplotlib.rcParams['font.family'] = ['KaiTi']
+matplotlib.rcParams['axes.unicode_minus']=False
+
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers,optimizers,losses
+from    tensorflow.keras.callbacks import EarlyStopping
+
+tf.random.set_seed(1234)
+np.random.seed(1234)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+from pokemon import  load_pokemon,normalize
+
+
+
+def preprocess(x,y):
+    # x: 图片的路径，y：图片的数字编码
+    x = tf.io.read_file(x)
+    x = tf.image.decode_jpeg(x, channels=3) # RGBA
+    x = tf.image.resize(x, [244, 244])
+
+    x = tf.image.random_flip_left_right(x)
+    x = tf.image.random_flip_up_down(x)
+    x = tf.image.random_crop(x, [224,224,3])
+
+    # x: [0,255]=> -1~1
+    x = tf.cast(x, dtype=tf.float32) / 255.
+    x = normalize(x)
+    y = tf.convert_to_tensor(y)
+    y = tf.one_hot(y, depth=5)
+
+    return x, y
+
+
+batchsz = 32
+# 创建训练集Datset对象
+images, labels, table = load_pokemon('pokemon',mode='train')
+db_train = tf.data.Dataset.from_tensor_slices((images, labels))
+db_train = db_train.shuffle(1000).map(preprocess).batch(batchsz)
+# 创建验证集Datset对象
+images2, labels2, table = load_pokemon('pokemon',mode='val')
+db_val = tf.data.Dataset.from_tensor_slices((images2, labels2))
+db_val = db_val.map(preprocess).batch(batchsz)
+# 创建测试集Datset对象
+images3, labels3, table = load_pokemon('pokemon',mode='test')
+db_test = tf.data.Dataset.from_tensor_slices((images3, labels3))
+db_test = db_test.map(preprocess).batch(batchsz)
+
+# 加载DenseNet网络模型，并去掉最后一层全连接层，最后一个池化层设置为max pooling
+net = keras.applications.DenseNet121(include_top=False, pooling='max')
+# 设计为不参与优化，即MobileNet这部分参数固定不动
+net.trainable = True
+newnet = keras.Sequential([
+    net, # 去掉最后一层的DenseNet121
+    layers.Dense(1024, activation='relu'), # 追加全连接层
+    layers.BatchNormalization(), # 追加BN层
+    layers.Dropout(rate=0.5), # 追加Dropout层，防止过拟合
+    layers.Dense(5) # 根据宝可梦数据的任务，设置最后一层输出节点数为5
+])
+newnet.build(input_shape=(4,224,224,3))
+newnet.summary()
+
+# 创建Early Stopping类，连续3次不下降则终止
+early_stopping = EarlyStopping(
+    monitor='val_accuracy',
+    min_delta=0.001,
+    patience=3
+)
+
+newnet.compile(optimizer=optimizers.Adam(lr=1e-3),
+               loss=losses.CategoricalCrossentropy(from_logits=True),
+               metrics=['accuracy'])
+history  = newnet.fit(db_train, validation_data=db_val, validation_freq=1, epochs=100,
+           callbacks=[early_stopping])
+history = history.history
+print(history.keys())
+print(history['val_accuracy'])
+print(history['accuracy'])
+test_acc = newnet.evaluate(db_test)
+
+plt.figure()
+returns = history['val_accuracy']
+plt.plot(np.arange(len(returns)), returns, label='验证准确率')
+plt.plot(np.arange(len(returns)), returns, 's')
+returns = history['accuracy']
+plt.plot(np.arange(len(returns)), returns, label='训练准确率')
+plt.plot(np.arange(len(returns)), returns, 's')
+
+plt.plot([len(returns)-1],[test_acc[-1]], 'D', label='测试准确率')
+plt.legend()
+plt.xlabel('Epoch')
+plt.ylabel('准确率')
+plt.savefig('scratch.svg')
\ No newline at end of file

ch15/train_transfer.py

+import  matplotlib
+from    matplotlib import pyplot as plt
+matplotlib.rcParams['font.size'] = 18
+matplotlib.rcParams['figure.titlesize'] = 18
+matplotlib.rcParams['figure.figsize'] = [9, 7]
+matplotlib.rcParams['font.family'] = ['KaiTi']
+matplotlib.rcParams['axes.unicode_minus']=False
+
+import  os
+import  tensorflow as tf
+import  numpy as np
+from    tensorflow import keras
+from    tensorflow.keras import layers,optimizers,losses
+from    tensorflow.keras.callbacks import EarlyStopping
+
+tf.random.set_seed(2222)
+np.random.seed(2222)
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
+assert tf.__version__.startswith('2.')
+
+
+from pokemon import  load_pokemon,normalize
+
+
+
+def preprocess(x,y):
+    # x: 图片的路径，y：图片的数字编码
+    x = tf.io.read_file(x)
+    x = tf.image.decode_jpeg(x, channels=3) # RGBA
+    x = tf.image.resize(x, [244, 244])
+
+    x = tf.image.random_flip_left_right(x)
+    x = tf.image.random_flip_up_down(x)
+    x = tf.image.random_crop(x, [224,224,3])
+
+    # x: [0,255]=> -1~1
+    x = tf.cast(x, dtype=tf.float32) / 255.
+    x = normalize(x)
+    y = tf.convert_to_tensor(y)
+    y = tf.one_hot(y, depth=5)
+
+    return x, y
+
+
+batchsz = 32
+# 创建训练集Datset对象
+images, labels, table = load_pokemon('pokemon',mode='train')
+db_train = tf.data.Dataset.from_tensor_slices((images, labels))
+db_train = db_train.shuffle(1000).map(preprocess).batch(batchsz)
+# 创建验证集Datset对象
+images2, labels2, table = load_pokemon('pokemon',mode='val')
+db_val = tf.data.Dataset.from_tensor_slices((images2, labels2))
+db_val = db_val.map(preprocess).batch(batchsz)
+# 创建测试集Datset对象
+images3, labels3, table = load_pokemon('pokemon',mode='test')
+db_test = tf.data.Dataset.from_tensor_slices((images3, labels3))
+db_test = db_test.map(preprocess).batch(batchsz)
+
+# 加载DenseNet网络模型，并去掉最后一层全连接层，最后一个池化层设置为max pooling
+net = keras.applications.DenseNet121(weights='imagenet', include_top=False, pooling='max')
+# 设计为不参与优化，即MobileNet这部分参数固定不动
+net.trainable = True
+newnet = keras.Sequential([
+    net, # 去掉最后一层的DenseNet121
+    layers.Dense(1024, activation='relu'), # 追加全连接层
+    layers.BatchNormalization(), # 追加BN层
+    layers.Dropout(rate=0.5), # 追加Dropout层，防止过拟合
+    layers.Dense(5) # 根据宝可梦数据的任务，设置最后一层输出节点数为5
+])
+newnet.build(input_shape=(4,224,224,3))
+newnet.summary()
+
+# 创建Early Stopping类，连续3次不下降则终止
+early_stopping = EarlyStopping(
+    monitor='val_accuracy',
+    min_delta=0.001,
+    patience=3
+)
+
+newnet.compile(optimizer=optimizers.Adam(lr=1e-3),
+               loss=losses.CategoricalCrossentropy(from_logits=True),
+               metrics=['accuracy'])
+history  = newnet.fit(db_train, validation_data=db_val, validation_freq=1, epochs=100,
+           callbacks=[early_stopping])
+history = history.history
+print(history.keys())
+print(history['val_accuracy'])
+print(history['accuracy'])
+test_acc = newnet.evaluate(db_test)
+
+plt.figure()
+returns = history['val_accuracy']
+plt.plot(np.arange(len(returns)), returns, label='验证准确率')
+plt.plot(np.arange(len(returns)), returns, 's')
+returns = history['accuracy']
+plt.plot(np.arange(len(returns)), returns, label='训练准确率')
+plt.plot(np.arange(len(returns)), returns, 's')
+
+plt.plot([len(returns)-1],[test_acc[-1]], 'D', label='测试准确率')
+plt.legend()
+plt.xlabel('Epoch')
+plt.ylabel('准确率')
+plt.savefig('transfer.svg')
\ No newline at end of file

ch9/nb.py

+#%%
+import tensorflow as tf 
+from    tensorflow.keras import layers
+
+pip install -U scikit-learn
+
+#%%
+# 添加dropout操作
+x = tf.nn.dropout(x, rate=0.5)
+# 添加Dropout层
+model.add(layers.Dropout(rate=0.5))
+
+# 手动计算每个张量的范数
+loss_reg = lambda_ * tf.reduce_sum(tf.square(w))
+# 在层方式时添加范数函数
+Dense(256, activation='relu',
+                    kernel_regularizer=regularizers.l2(_lambda))
+
+#%%
+#                     
+# 创建网络参数w1,w2
+w1 = tf.random.normal([4,3])
+w2 = tf.random.normal([4,2])
+# 计算L1正则化项
+loss_reg = tf.reduce_sum(tf.math.abs(w1))\
+    + tf.reduce_sum(tf.math.abs(w2))
+
+
+# 计算L2正则化项
+loss_reg = tf.reduce_sum(tf.square(w1))\
+    + tf.reduce_sum(tf.square(w2))
+
+#%%
+loss_reg
+
+#%%