cifar10神经网络训练测试及代码解析

港控/mmm° 2022-06-08 01:13 332阅读 0赞

cifar10是nclass = 10的分类问题，共采用两层卷积层(conv),两层maxpool层，3层全连接层，最后一层为softmax层。数据类型为二进制文件：CIFAR-10 binary version (suitable for C programs)。  
可从cifar数据官网下载：[https://www.cs.toronto.edu/~kriz/cifar.html][https_www.cs.toronto.edu_kriz_cifar.html]，  
代码一共分为三部分：读取数据，训练模型，测试模型。开发环境采用sublime上的搭建的python环境。

**1.读取数据**

import os
    os.environ['TF_CPP_MIN_LOG_LEVEL']='2'
    import tensorflow as tf
    import numpy as np
    
    
    def input_cifar10(file_dir,is_train,batch_size,shuffle):
        '''
        Args:
            file_dir: file path
            batch_size: Number of images per batch
            shuffle : boolean indicating whether to use a shuffling queue
        Outputs:
            image tensor: image. 4D tensor of [batch_size, height, width, depth] size.
            label tensor: labels. 1D tensor of [batch_size] size.
        '''
        image_height = 32
        image_width = 32
        image_depth = 3
        label_bytes = 1
        image_bytes = image_width*image_height*image_depth
        record_bytes = image_bytes+label_bytes
        # input queue
        file_list = os.listdir(file_dir)
    
        if is_train:
            filenames = [os.path.join(file_dir,'data_batch_%d.bin' % ii) for ii in range(1,6)]
        else:
            filenames = [os.path.join(file_dir,'test_batch.bin')]
    
        filename_queue = tf.train.string_input_producer(filenames)
        #reader
        reader = tf.FixedLengthRecordReader(record_bytes=record_bytes)
        key, value = reader.read(filename_queue)
        record_bytes = tf.decode_raw(value, tf.uint8)
        #generate label and float_image
        label = tf.cast(tf.strided_slice(record_bytes, [0], [label_bytes]), tf.int32)
    
        image = tf.reshape(tf.strided_slice(record_bytes,[label_bytes],
                                            [label_bytes + image_bytes]),
                                            [image_depth, image_height, image_width])
        image = tf.transpose(image, [1, 2, 0])
        reshape_image = tf.cast(image, tf.float32)
        resized_image = tf.image.resize_image_with_crop_or_pad(reshape_image,
                                                                image_height, image_width)
        float_image = tf.image.per_image_standardization(resized_image)
        float_image = tf.reshape(float_image,[image_height, image_width, 3])
        label = tf.reshape(label,[1])
        if shuffle:
            images, label_batch = tf.train.shuffle_batch([float_image, label],
                                                        batch_size=batch_size,
                                                        num_threads=16,
                                                        capacity= 500,
                                                        min_after_dequeue = 300)
        else:
            images, label_batch = tf.train.batch([float_image, label],
                                                batch_size=batch_size,
                                                num_threads=16,
                                                capacity=500)
        label_batch = tf.reshape(label_batch, [batch_size])
    
        print(images)
    
        return images, label_batch

**2.训练模型**

import os
    import tensorflow as tf
    import numpy as np
    import input_cifar10
    
    n_class = 10
    image_H = 32
    image_W = 32
    CAPACITY = 2000
    BATCH_SIZE = 128
    MAX_STEP = 9999
    learning_rate = 0.05
    
    def inference(images,batch_size,n_classes):
        '''
        Args:
            images: images
            labels:label_batch
        Returns:
            logits.
        '''
        #conv1
        with tf.variable_scope('conv1') as scope:
            weights = tf.get_variable('weights',
                                        shape = [5,5,3,64],
                                        dtype = tf.float32,
                                        initializer = tf.truncated_normal_initializer(stddev = 0.005,dtype = tf.float32))
            conv = tf.nn.conv2d(images,weights,[1,1,1,1],padding = 'SAME')
            biases = tf.get_variable('biases',
                                    shape = [64],
                                    dtype = tf.float32,
                                    initializer = tf.constant_initializer(0.0))
            pre_activation = tf.nn.bias_add(conv,biases)
            conv1 = tf.nn.relu(pre_activation,name = scope.name)
        # pooling 1 and norm 1
        pool1 = tf.nn.max_pool(conv1,ksize = [1,3,3,1],strides = [1,2,2,1],
                                padding = 'SAME',name = 'pool1')
    
        norm1 = tf.nn.lrn(pool1,4,bias = 1.0,alpha=0.001/9.0,beta=0.75,
                            name = 'norm1')
        print(conv1,pool1,norm1)
        #conv2
        with tf.variable_scope('conv2') as scope:
            weights = tf.get_variable('weights',
                                        shape = [5,5,64,64],
                                        dtype = tf.float32,
                                        initializer = tf.truncated_normal_initializer(stddev = 0.005,dtype = tf.float32))
            conv = tf.nn.conv2d(norm1,weights,[1,1,1,1],padding = 'SAME')
            biases = tf.get_variable('biases',
                                    shape = [64],
                                    dtype = tf.float32,
                                    initializer = tf.constant_initializer(0.0))
            pre_activation = tf.nn.bias_add(conv,biases)
            conv2 = tf.nn.relu(pre_activation,name = scope.name)
        # pooling 2 and norm 2
        norm2 = tf.nn.lrn(conv2,4,bias = 1.0,alpha=0.001/9.0,beta=0.75,
                            name = 'norm2')
        pool2 = tf.nn.max_pool(norm2,ksize = [1,3,3,1],strides = [1,2,2,1],
                            padding = 'SAME',name = 'pool2')
        print([conv2,norm2,pool2])
    
        #local3--fc
        with tf.variable_scope('local3') as scope:
            reshape = tf.reshape (pool2,shape = [batch_size, -1])
            dim = reshape.get_shape()[1].value
            weights = tf.get_variable('weights', shape=[dim, 384],
                                       dtype = tf.float32,
                                       initializer = tf.truncated_normal_initializer(stddev=0.04,dtype=tf.float32))
            biases = tf.get_variable('biases', [384], 
                                          dtype = tf.float32,
                                          initializer = tf.constant_initializer(0.1))
            local3 = tf.nn.relu(tf.matmul(reshape, weights) + biases, name=scope.name)
        #local4
        with tf.variable_scope('local4') as scope:
            weights = tf.get_variable('weights', shape=[384, 192],
                                       dtype = tf.float32,
                                       initializer = tf.truncated_normal_initializer(stddev=0.04,dtype=tf.float32))
            biases = tf.get_variable('biases', [192], 
                                      dtype = tf.float32,
                                      initializer = tf.constant_initializer(0.1))
            local4 = tf.nn.relu(tf.matmul(local3, weights) + biases, name=scope.name)
        #local5
        with tf.variable_scope('softmax_linear') as scope:
            weights = tf.get_variable('weights', shape=[192, n_classes],
                                       dtype = tf.float32,
                                       initializer = tf.truncated_normal_initializer(stddev=1/192.0,dtype=tf.float32))
            biases = tf.get_variable('biases', [n_classes], 
                                      dtype = tf.float32,
                                      initializer = tf.constant_initializer(0.0))
            softmax_linear = tf.add(tf.matmul(local4, weights) ,biases, name='softmax_linear')
        return softmax_linear
    # losses
    def losses(logits, labels):
        '''
        args:
            logits: logits tensor, float, [batch_size, n_classes]
            labels: labels tensor,tf.int32,[batch_size]
    
        returns:
            loss tensor of float type
        '''
        with tf.variable_scope('loss') as scope:
            cross_entropy = tf.nn.sparse_softmax_cross_entropy_with_logits(logits=logits, 
                                                                           labels= labels,
                                                                           name='cross_entropy_per_example')
            loss = tf.reduce_mean(cross_entropy, name='loss')
            tf.summary.scalar(scope.name+'/loss',loss)
        return loss
    #training
    def train(loss,learning_rate):
        '''
        args:
            loss:loss tensor
        returns:
            train_op: the op for training
        '''
        with tf.name_scope('optimizer'):
            optimizer = tf.train.AdamOptimizer(learning_rate = learning_rate)
            global_step = tf.Variable(0,name='global_step', trainable=False)
            train_op = optimizer.minimize(loss,global_step = global_step)
        return train_op
    
    #evaluation
    def evalution(logits, labels):
        with tf.variable_scope('accuracy') as scope:
            correct = tf.nn.in_top_k(logits, labels,1)
            correct = tf.cast(correct,tf.float16)
            accuracy = tf.reduce_mean(correct)
            tf.summary.scalar(scope.name+'/accuracy',accuracy)
        return accuracy 
    
    #run training
    train_dir = 'D:/tensorflow/cifar10/cifar-10-batches-bin/'
    logits_train_dir = 'D:/tensorflow/cifar10/logits/'
    if not os.path.exists(logits_train_dir):
        os.makedirs(logits_train_dir)
    train_batch,train_label_batch = input_cifar10.input_cifar10(train_dir,
                                            is_train =True,
                                            batch_size = BATCH_SIZE,
                                            shuffle= False)
    logits_train = model_cifar.inference(train_batch,BATCH_SIZE,n_class)
    loss = model_cifar.losses(logits_train,train_label_batch)
    train_op = model_cifar.train(loss,learning_rate)
    accuracy = model_cifar.evalution(logits_train,train_label_batch)
    
    summary_op = tf.summary.merge_all()
    sess = tf.Session()
    train_writer = tf.summary.FileWriter(logits_train_dir,sess.graph)
    saver = tf.train.Saver()
    
    sess.run(tf.global_variables_initializer())
    coord = tf.train.Coordinator()
    threads = tf.train.start_queue_runners(sess = sess, coord = coord) 
    
    try:
        for step in np.arange(MAX_STEP):
            if coord.should_stop():
                break
            _,train_loss,train_accuracy = sess.run([train_op,loss,accuracy])
    
            if step % 100 == 0:
                print('Step %d, train loss = %.2f, train_accuracy = %.2f' %(step,train_loss,train_accuracy))
                summary_str = sess.run(summary_op)
                train_writer.add_summary(summary_str, step)
            if step % 200 == 0:
                checkpoint_path = os.path.join(logits_train_dir, 'model.ckpt')
                saver.save(sess,checkpoint_path,global_step = step)
    
    except tf.errors.OutOfRangeError:
        print('done!')
    finally:
        coord.request_stop()
    coord.join(threads)

**3.评估模型**

import os
    import tensorflow as tf
    import numpy as np
    import input_cifar10
    import model_cifar
    import math
    import datetime
    # constant
    BATCH_SIZE = 128
    test_dir = 'D:/tensorflow/cifar10/cifar-10-batches-bin/'
    checkpoint_dir = 'D:/tensorflow/cifar10/logits/'
    n_tests = 10000
    #test_dir_logits2 = 'D:/tensorflow/cifar10/logits2/'
    
    with tf.Graph().as_default() as g:
        images,labels = input_cifar10.input_cifar10(test_dir,
                                                is_train =False,
                                                batch_size = BATCH_SIZE,
                                                shuffle= False)
        #inferenece model
        logits = model_cifar.inference(images,batch_size = BATCH_SIZE,n_classes = 10)
        #calculate predictions
        top_k_op = tf.nn.in_top_k(logits,labels,1)
    
        saver = tf.train.Saver(tf.global_variables())
    
        #summary_op = tf.summary.merge_all()
    
        #summary_writer = tf.summary.FileWriter(test_dir_logits2, g)
    
    
        with tf.Session() as sess:
    
            print('Reading checkpoints...')
            ckpt = tf.train.get_checkpoint_state(checkpoint_dir)
            if ckpt and ckpt.model_checkpoint_path:
                saver.restore(sess, ckpt.model_checkpoint_path)
                global_step  = ckpt.model_checkpoint_path.split('/')[-1].split('-')[-1]
                print('loading success,global_step is %s' % global_step)
            else:
                print('No checkpoint file found')
    
            coord = tf.train.Coordinator()
            threads = tf.train.start_queue_runners(sess = sess, coord = coord)
    
            try:
    
                num_iter = int(math.ceil(n_tests/ BATCH_SIZE))
                true_count = 0  # Counts the number of correct predictions.
                total_sample_count = num_iter * BATCH_SIZE
                step = 0
                while step < num_iter and not coord.should_stop():
                    predictions = sess.run([top_k_op])
                    true_count += np.sum(predictions)
                    step += 1
    
                  # Compute precision @ 1.
                    precision = true_count / total_sample_count
                print('precision = %.3f' %  precision)
    
            except Exception as e:  # pylint: disable=broad-except
                    coord.request_stop(e)
            finally:
                    coord.request_stop()
                    coord.join(threads)

## 代码解析 ##

1.cnn神经网络读取固定长度二进制文件的基本流程  
(1).read data(FixedLengthRecordReader,decode\_raw)  
(2).generate batch  
(3).feed in tensorflow graph  
(4)train  
(5)validation  
2.网络  
input = \[batch, in\_channels， in\_height, in\_width\]  
输出神经网络的卷积层及池化层，可以发现卷积层与原始图像的尺寸一致，这是因为代码中采用zero-padding的填补方式，保证图像的大小不至于因为卷积而缩小。  
input = \[BATCH\_SIZE = 128,32,32,3\]  
CONV1 = \[128,32,32,64\]  
POOL1 = \[128,16,16,64\]  
CONV2 = \[128,16,16,64\]  
POOL2 = \[128,8,8,64\]  
LOCAL3 = \[128,384\]  
……  
![这里写图片描述][SouthEast]  
3.strides and ksize  
ksize表示卷积核的大小\[height,width,in\_channels, out\_channels\]  
stides表示卷积核的滑移距离，strides = \[batch , in\_height , in\_width, in\_channels\]  
4.padding：表示填充方式：“SAME”表示采用填充的方式，简单地理解为以0填充边缘，但还有一个要求，左边（上边）补0的个数和右边（下边）补0的个数一样或少一个，“VALID”表示采用不填充的方式，多余地进行丢弃。具体公式：  
“SAME”: output\_spatial\_shape\[i\]=(input\_spatial\_shape\[i\] / strides\[i\])  
“VALID”: output\_spatial\_shape\[i\]=((input\_spatial\_shape\[i\]-(spatial\_filter\_shape\[i\]-1)/strides\[i\])

参考文献  
1.[https://www.leiphone.com/news/201705/HH3BbIfCqAtOAMbu.html][https_www.leiphone.com_news_201705_HH3BbIfCqAtOAMbu.html]  
2.[http://m.blog.csdn.net/v\_JULY\_v/article/details/51812459][http_m.blog.csdn.net_v_JULY_v_article_details_51812459]  
3.[https://www.zhihu.com/question/52668301][https_www.zhihu.com_question_52668301]  
4.[http://m.blog.csdn.net/u011974639/article/details/75363565][http_m.blog.csdn.net_u011974639_article_details_75363565]

[https_www.cs.toronto.edu_kriz_cifar.html]: https://www.cs.toronto.edu/~kriz/cifar.html
[SouthEast]: /images/20220608/8f820cc466704a2b92f78e36fff993ce.png
[https_www.leiphone.com_news_201705_HH3BbIfCqAtOAMbu.html]: https://www.leiphone.com/news/201705/HH3BbIfCqAtOAMbu.html
[http_m.blog.csdn.net_v_JULY_v_article_details_51812459]: http://m.blog.csdn.net/v_JULY_v/article/details/51812459
[https_www.zhihu.com_question_52668301]: https://www.zhihu.com/question/52668301
[http_m.blog.csdn.net_u011974639_article_details_75363565]: http://m.blog.csdn.net/u011974639/article/details/75363565