【北京大学】11 TensorFlow1.x的卷积神经网络模型Lenet5实现

矫情吗；* 2022-12-29 09:38 93阅读 0赞

### 目录 ###

*  1 Lenet5模型简介
 *  2 TensorFlow实现
 *   *  mnist\_lenet5\_forward.py文件
     *  mnist\_lenet5\_backward.py文件
     *  mnist\_lenet5\_test.py文件
 *  相关笔记

# 1 Lenet5模型简介 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzNTY5Ng_size_16_color_FFFFFF_t_70_pic_center]

# 2 TensorFlow实现 #

## mnist\_lenet5\_forward.py文件 ##

import tensorflow as tf
    # 每张图片分辨率为28*28
    IMAGE_SIZE = 28
    # Mnist数据集为灰度图，故输入图片通道数NUM_CHANNELS取值为1
    NUM_CHANNELS = 1
    # 第一层卷积核大小为5
    CONV1_SIZE = 5
    # 卷积核个数为32
    CONV1_KERNEL_NUM = 32
    # 第二层卷积核大小为5
    CONV2_SIZE = 5
    # 卷积核个数为64
    CONV2_KERNEL_NUM = 64
    # 全连接层第一层为 512 个神经元
    FC_SIZE = 512
    # 全连接层第二层为 10 个神经元
    OUTPUT_NODE = 10
    # 权重w计算
    def get_weight(shape, regularizer):
        w = tf.Variable(tf.truncated_normal(shape, stddev=0.1))
        if regularizer != None: tf.add_to_collection('losses', tf.contrib.layers.l2_regularizer(regularizer)(w))
        return w
    # 偏置b计算
    def get_bias(shape):
        b = tf.Variable(tf.zeros(shape))
        return b
    # 卷积层计算
    def conv2d(x, w):
        return tf.nn.conv2d(x, w, strides=[1, 1, 1, 1], padding='SAME')
    # 最大池化层计算
    def max_pool_2x2(x):
        return tf.nn.max_pool(x, ksize=[1, 2, 2, 1], strides=[1, 2, 2, 1], padding='SAME')
    def forward(x, train, regularizer):
        # 实现第一层卷积
        conv1_w = get_weight([CONV1_SIZE, CONV1_SIZE, NUM_CHANNELS, CONV1_KERNEL_NUM], regularizer)
        conv1_b = get_bias([CONV1_KERNEL_NUM])
        conv1 = conv2d(x, conv1_w)
        # 非线性激活
        relu1 = tf.nn.relu(tf.nn.bias_add(conv1, conv1_b))
        # 最大池化
        pool1 = max_pool_2x2(relu1)
        # 实现第二层卷积
        conv2_w = get_weight([CONV2_SIZE, CONV2_SIZE, CONV1_KERNEL_NUM, CONV2_KERNEL_NUM], regularizer)
        conv2_b = get_bias([CONV2_KERNEL_NUM])
        conv2 = conv2d(pool1, conv2_w)
        relu2 = tf.nn.relu(tf.nn.bias_add(conv2, conv2_b))
        pool2 = max_pool_2x2(relu2)
        # 获取一个张量的维度
        pool_shape = pool2.get_shape().as_list()
        # pool_shape[1] 为长 pool_shape[2] 为宽 pool_shape[3]为高
        nodes = pool_shape[1] * pool_shape[2] * pool_shape[3]
        # 得到矩阵被拉长后的长度，pool_shape[0]为batch值
        reshaped = tf.reshape(pool2, [pool_shape[0], nodes])
        # 实现第三层全连接层
        fc1_w = get_weight([nodes, FC_SIZE], regularizer)
        fc1_b = get_bias([FC_SIZE])
        fc1 = tf.nn.relu(tf.matmul(reshaped, fc1_w) + fc1_b)
        # 如果是训练阶段，则对该层输出使用dropout
        if train: fc1 = tf.nn.dropout(fc1, 0.5)
        # 实现第四层全连接层
        fc2_w = get_weight([FC_SIZE, OUTPUT_NODE], regularizer)
        fc2_b = get_bias([OUTPUT_NODE])
        y = tf.matmul(fc1, fc2_w) + fc2_b
        return y

## mnist\_lenet5\_backward.py文件 ##

import tensorflow as tf
    from tensorflow.examples.tutorials.mnist import input_data
    import mnist_lenet5_forward
    import os
    import numpy as np
    # batch的数量
    BATCH_SIZE = 100
    # 初始学习率
    LEARNING_RATE_BASE = 0.005
    # 学习率衰减率
    LEARNING_RATE_DECAY = 0.99
    # 正则化
    REGULARIZER = 0.0001
    # 最大迭代次数
    STEPS = 50000
    # 滑动平均衰减率
    MOVING_AVERAGE_DECAY = 0.99
    # 模型保存路径
    MODEL_SAVE_PATH = "./model/"
    # 模型名称
    MODEL_NAME = "mnist_model"
    def backward(mnist):
        # 卷积层输入为四阶张量
        # 第一阶表示每轮喂入的图片数量，第二阶和第三阶分别表示图片的行分辨率和列分辨率，第四阶表示通道数
        x = tf.placeholder(tf.float32, [
            BATCH_SIZE,
            mnist_lenet5_forward.IMAGE_SIZE,
            mnist_lenet5_forward.IMAGE_SIZE,
            mnist_lenet5_forward.NUM_CHANNELS])
        y_ = tf.placeholder(tf.float32, [None, mnist_lenet5_forward.OUTPUT_NODE])
        # 前向传播过程
        y = mnist_lenet5_forward.forward(x, True, REGULARIZER)
        # 声明一个全局计数器
        global_step = tf.Variable(0, trainable=False)
        # 对网络最后一层的输出y做softmax，求取输出属于某一类的概率
        ce = tf.nn.sparse_softmax_cross_entropy_with_logits(logits=y, labels=tf.argmax(y_, 1))
        # 向量求均值
        cem = tf.reduce_mean(ce)
        # 正则化的损失值
        loss = cem + tf.add_n(tf.get_collection('losses'))
        # 指数衰减学习率
        learning_rate = tf.train.exponential_decay(
            LEARNING_RATE_BASE,
            global_step,
            mnist.train.num_examples / BATCH_SIZE,
            LEARNING_RATE_DECAY,
            staircase=True)
        # 梯度下降算法的优化器
        # train_step = tf.train.GradientDescentOptimizer(learning_rate).minimize(loss, global_step=global_step)
        train_step = tf.train.MomentumOptimizer(learning_rate, 0.9).minimize(loss, global_step=global_step)
        # 采用滑动平均的方法更新参数
        ema = tf.train.ExponentialMovingAverage(MOVING_AVERAGE_DECAY, global_step)
        ema_op = ema.apply(tf.trainable_variables())
        # 将train_step和ema_op两个训练操作绑定到train_op上
        with tf.control_dependencies([train_step, ema_op]):
            train_op = tf.no_op(name='train')
        # 实例化一个保存和恢复变量的saver
        saver = tf.train.Saver()
        # 创建一个会话
        with tf.Session() as sess:
            init_op = tf.global_variables_initializer()
            sess.run(init_op)
            # 通过 checkpoint 文件定位到最新保存的模型，若文件存在，则加载最新的模型
            ckpt = tf.train.get_checkpoint_state(MODEL_SAVE_PATH)
            if ckpt and ckpt.model_checkpoint_path:
                saver.restore(sess, ckpt.model_checkpoint_path)
            for i in range(STEPS):
                # 读取一个batch数据，将输入数据xs转成与网络输入相同形状的矩阵
                xs, ys = mnist.train.next_batch(BATCH_SIZE)
                reshaped_xs = np.reshape(xs, (
                    BATCH_SIZE,
                    mnist_lenet5_forward.IMAGE_SIZE,
                    mnist_lenet5_forward.IMAGE_SIZE,
                    mnist_lenet5_forward.NUM_CHANNELS))
                # 读取一个batch数据，将输入数据xs转成与网络输入相同形状的矩阵
                _, loss_value, step = sess.run([train_op, loss, global_step], feed_dict={ x: reshaped_xs, y_: ys})
                if i % 100 == 0:
                    print("After %d training step(s), loss on training batch is %g." % (step, loss_value))
                    saver.save(sess, os.path.join(MODEL_SAVE_PATH, MODEL_NAME), global_step=global_step)
    def main():
        mnist = input_data.read_data_sets("./data/", one_hot=True)
        backward(mnist)
    if __name__ == '__main__':
        main()

## mnist\_lenet5\_test.py文件 ##

import time
    import tensorflow as tf
    from tensorflow.examples.tutorials.mnist import input_data
    import mnist_lenet5_forward
    import mnist_lenet5_backward
    import numpy as np
    TEST_INTERVAL_SECS = 5
    #创建一个默认图，在该图中执行以下操作
    def test(mnist):
        with tf.Graph().as_default() as g: 
            x = tf.placeholder(tf.float32,[
                mnist.test.num_examples,
                mnist_lenet5_forward.IMAGE_SIZE,
                mnist_lenet5_forward.IMAGE_SIZE,
                mnist_lenet5_forward.NUM_CHANNELS]) 
            y_ = tf.placeholder(tf.float32, [None, mnist_lenet5_forward.OUTPUT_NODE])
            #训练好的网络，故不使用 dropout
            y = mnist_lenet5_forward.forward(x,False,None)
            ema = tf.train.ExponentialMovingAverage(mnist_lenet5_backward.MOVING_AVERAGE_DECAY)
            ema_restore = ema.variables_to_restore()
            saver = tf.train.Saver(ema_restore)
            #判断预测值和实际值是否相同
            correct_prediction = tf.equal(tf.argmax(y, 1), tf.argmax(y_, 1)) 
            ## 求平均得到准确率
            accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32)) 
            while True:
                with tf.Session() as sess:
                    ckpt = tf.train.get_checkpoint_state(mnist_lenet5_backward.MODEL_SAVE_PATH)
                    if ckpt and ckpt.model_checkpoint_path:
                        saver.restore(sess, ckpt.model_checkpoint_path) 
                        # 根据读入的模型名字切分出该模型是属于迭代了多少次保存的
                        global_step = ckpt.model_checkpoint_path.split('/')[-1].split('-')[-1] 
                        reshaped_x = np.reshape(mnist.test.images,(
                        mnist.test.num_examples,
                        mnist_lenet5_forward.IMAGE_SIZE,
                        mnist_lenet5_forward.IMAGE_SIZE,
                        mnist_lenet5_forward.NUM_CHANNELS))
                        #利用多线程提高图片和标签的批获取效率
                        coord = tf.train.Coordinator()#3
                        threads = tf.train.start_queue_runners(sess=sess, coord=coord)#4
                        accuracy_score = sess.run(accuracy, feed_dict={ x:reshaped_x,y_:mnist.test.labels}) 
                        print("After %s training step(s), test accuracy = %g" % (global_step, accuracy_score))
                        #关闭线程协调器
                        coord.request_stop()#6
                        coord.join(threads)#7
                    else:
                        print('No checkpoint file found')
                        return
                time.sleep(TEST_INTERVAL_SECS) 
    def main():
        mnist = input_data.read_data_sets("./data/", one_hot=True)
        test(mnist)
    if __name__ == '__main__':
        main()

# 相关笔记 #

以下所有源码以及更详细PDF笔记请在github下载  
[TensorFolwNotebook-from-Peking-University][]

1.  [【北京大学】1 TensorFlow1.x中Python基础知识][1 TensorFlow1.x_Python]
2.  [【北京大学】2 TensorFlow1.x的张量、计算图、会话][2 TensorFlow1.x]
3.  [【北京大学】3 TensorFlow1.x的前向传播推导与实现][3 TensorFlow1.x]
4.  [【北京大学】4 TensorFlow1.x的反向传播推导与实现][4 TensorFlow1.x]
5.  [【北京大学】5 TensorFlow1.x的损失函数和交叉熵举例讲解及实现][5 TensorFlow1.x]
6.  [【北京大学】6 TensorFlow1.x的学习率、滑动平均和正则化实例及实现][6 TensorFlow1.x]
7.  [【北京大学】7 TensorFlow1.x的神经网络模块设计思想举例及实现][7 TensorFlow1.x]
8.  [【北京大学】8 TensorFlow1.x的Mnist数据集实例实现][8 TensorFlow1.x_Mnist]
9.  [【北京大学】9 TensorFlow1.x的实现自定义Mnist数据集][9 TensorFlow1.x_Mnist]
10. [【北京大学】10 TensorFlow1.x的卷积神经网络(CNN)相关基础知识][10 TensorFlow1.x_CNN]
11. [【北京大学】11 TensorFlow1.x的卷积神经网络模型Lenet5实现][11 TensorFlow1.x_Lenet5]
12. [【北京大学】12 TensorFlow1.x的卷积神经网络模型VGGNet实现][12 TensorFlow1.x_VGGNet]
13. [【北京大学】13 TensorFlow1.x的项目实战之手写英文体识别OCR技术][13 TensorFlow1.x_OCR]
14. [【北京大学】14 TensorFlow1.x的二值神经网络实现MNIST数据集手写数字识别][14 TensorFlow1.x_MNIST]
15. [【北京大学】15 TensorFlow1.x的项目实战之人脸表情识别][15 TensorFlow1.x]
16. [【北京大学】16 TensorFlow1.x的项目实战之图像风格融合与快速迁移][16 TensorFlow1.x]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzNTY5Ng_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/8eb380a1fdeb4ec0881954b5f1bbcaf0.png
[TensorFolwNotebook-from-Peking-University]: https://github.com/823316627bandeng/-TensorFolwNotebook-from-Peking-University
[1 TensorFlow1.x_Python]: https://betterbench.blog.csdn.net/article/details/111400935
[2 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111401620
[3 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111407104
[4 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111407700
[5 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111409255
[6 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111410367
[7 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111410935
[8 TensorFlow1.x_Mnist]: https://betterbench.blog.csdn.net/article/details/111414788
[9 TensorFlow1.x_Mnist]: https://betterbench.blog.csdn.net/article/details/111480327
[10 TensorFlow1.x_CNN]: https://betterbench.blog.csdn.net/article/details/111495960
[11 TensorFlow1.x_Lenet5]: https://betterbench.blog.csdn.net/article/details/111499496
[12 TensorFlow1.x_VGGNet]: https://betterbench.blog.csdn.net/article/details/111516848
[13 TensorFlow1.x_OCR]: https://betterbench.blog.csdn.net/article/details/111567501
[14 TensorFlow1.x_MNIST]: https://betterbench.blog.csdn.net/article/details/111590573
[15 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111594356
[16 TensorFlow1.x]: https://betterbench.blog.csdn.net/article/details/111641487