CNN卷积神经网络实现Mnist手写数字识别数据集

# coding: utf-8 import tensorflow as tf from tensorflow.examples.tutorials.mnist import input_data #载入数据集 mnist = input_data.read_data_sets('MNIST_data',one_hot=True) #每个批次的大小 batch_size = 100 #计算一共有多少个批次 n_batch = mnist.train.num_examples // batch_size #参数概要 def variable_summaries(var): with tf.name_scope('summaries'): mean = tf.reduce_mean(var) tf.summary.scalar('mean', mean)#平均值 with tf.name_scope('stddev'): stddev = tf.sqrt(tf.reduce_mean(tf.square(var - mean))) tf.summary.scalar('stddev', stddev)#标准差 tf.summary.scalar('max', tf.reduce_max(var))#最大值 tf.summary.scalar('min', tf.reduce_min(var))#最小值 tf.summary.histogram('histogram', var)#直方图 #定义初始化权值函数 def weight_variable(shape,name): initial = tf.truncated_normal(shape,stddev=0.1) return tf.Variable(initial,name=name) #定义初始化偏置函数 def bias_variable(shape,name): initial = tf.constant(0.1,shape=shape) return tf.Variable(initial,name=name) #卷积层 def conv2d(x,W): return tf.nn.conv2d(x,W,strides=[1,1,1,1],padding='SAME') #池化层 def max_pool_2x2(x): return tf.nn.max_pool(x,ksize=[1,2,2,1],strides=[1,2,2,1],padding='SAME') #输入层 #命名空间 with tf.name_scope('input'): #定义两个placeholder x = tf.placeholder(tf.float32,[None,784],name='x-input') y = tf.placeholder(tf.float32,[None,10],name='y-input') with tf.name_scope('x_image'): #改变x的格式转为4D的向量[batch, in_height, in_width, in_channels]` x_image = tf.reshape(x,[-1,28,28,1],name='x_image') #第一个卷积层，激活层，池化层 with tf.name_scope('Conv1'): #初始化第一个卷积层的权值和偏置 with tf.name_scope('W_conv1'): W_conv1 = weight_variable([5,5,1,32],name='W_conv1')#5*5的采样窗口，32个卷积核从1个平面抽取特征 with tf.name_scope('b_conv1'): b_conv1 = bias_variable([32],name='b_conv1')#每一个卷积核一个偏置值 #把x_image和权值向量进行卷积，再加上偏置值，然后应用于relu激活函数 with tf.name_scope('conv2d_1'): conv2d_1 = conv2d(x_image,W_conv1) + b_conv1 with tf.name_scope('relu'): h_conv1 = tf.nn.relu(conv2d_1) with tf.name_scope('h_pool1'): h_pool1 = max_pool_2x2(h_conv1)#进行max-pooling池化 #第二个卷积层，激活层，池化层 with tf.name_scope('Conv2'): #初始化第二个卷积层的权值和偏置 with tf.name_scope('W_conv2'): W_conv2 = weight_variable([5,5,32,64],name='W_conv2')#5*5的采样窗口，64个卷积核从32个平面抽取特征 with tf.name_scope('b_conv2'): b_conv2 = bias_variable([64],name='b_conv2')#每一个卷积核一个偏置值 #把h_pool1和权值向量进行卷积，再加上偏置值，然后应用于relu激活函数 with tf.name_scope('conv2d_2'): conv2d_2 = conv2d(h_pool1,W_conv2) + b_conv2 with tf.name_scope('relu'): h_conv2 = tf.nn.relu(conv2d_2) with tf.name_scope('h_pool2'): h_pool2 = max_pool_2x2(h_conv2)#进行max-pooling #第一个全连接层 with tf.name_scope('fc1'): #初始化第一个全连接层的权值 with tf.name_scope('W_fc1'): W_fc1 = weight_variable([7*7*64,1024],name='W_fc1')#经过池化后有7*7*64个神经元，全连接层有1024个神经元 with tf.name_scope('b_fc1'): b_fc1 = bias_variable([1024],name='b_fc1')#1024个节点 #把池化层2的输出扁平化为1维 with tf.name_scope('h_pool2_flat'): h_pool2_flat = tf.reshape(h_pool2,[-1,7*7*64],name='h_pool2_flat') #求第一个全连接层的输出 with tf.name_scope('wx_plus_b1'): wx_plus_b1 = tf.matmul(h_pool2_flat,W_fc1) + b_fc1 with tf.name_scope('relu'): h_fc1 = tf.nn.relu(wx_plus_b1) #keep_prob用来表示神经元的输出概率 with tf.name_scope('keep_prob'): keep_prob = tf.placeholder(tf.float32,name='keep_prob') with tf.name_scope('h_fc1_drop'): h_fc1_drop = tf.nn.dropout(h_fc1,keep_prob,name='h_fc1_drop') #第二个全连接层（输出层） with tf.name_scope('fc2'): #初始化第二个全连接层 with tf.name_scope('W_fc2'): W_fc2 = weight_variable([1024,10],name='W_fc2') with tf.name_scope('b_fc2'): b_fc2 = bias_variable([10],name='b_fc2') with tf.name_scope('wx_plus_b2'): wx_plus_b2 = tf.matmul(h_fc1_drop,W_fc2) + b_fc2 with tf.name_scope('softmax'): #计算输出 prediction = tf.nn.softmax(wx_plus_b2) #交叉熵代价函数 with tf.name_scope('cross_entropy'): cross_entropy = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(labels=y,logits=prediction),name='cross_entropy') tf.summary.scalar('cross_entropy',cross_entropy) #使用AdamOptimizer进行优化 with tf.name_scope('train'): train_step = tf.train.AdamOptimizer(1e-4).minimize(cross_entropy) #求准确率 with tf.name_scope('accuracy'): with tf.name_scope('correct_prediction'): #结果存放在一个布尔列表中 correct_prediction = tf.equal(tf.argmax(prediction,1),tf.argmax(y,1))#argmax返回一维张量中最大的值所在的位置 with tf.name_scope('accuracy'): #求准确率 accuracy = tf.reduce_mean(tf.cast(correct_prediction,tf.float32)) tf.summary.scalar('accuracy',accuracy) #合并所有的summary merged = tf.summary.merge_all() #创建会话 with tf.Session() as sess: sess.run(tf.global_variables_initializer()) train_writer = tf.summary.FileWriter('logs/train',sess.graph) #训练集计算图写入日志文件 test_writer = tf.summary.FileWriter('logs/test',sess.graph) #测试集计算图写入日志文件 for i in range(1001): #训练模型 batch_xs,batch_ys = mnist.train.next_batch(batch_size) sess.run(train_step,feed_dict={x:batch_xs,y:batch_ys,keep_prob:0.5}) #记录训练集计算的参数 summary = sess.run(merged,feed_dict={x:batch_xs,y:batch_ys,keep_prob:1.0}) train_writer.add_summary(summary,i) #记录测试集计算的参数 batch_xs,batch_ys = mnist.test.next_batch(batch_size) summary = sess.run(merged,feed_dict={x:batch_xs,y:batch_ys,keep_prob:1.0}) test_writer.add_summary(summary,i) if i%100==0: test_acc = sess.run(accuracy, feed_dict={x: mnist.test.images, y: mnist.test.labels, keep_prob: 1.0}) train_acc = sess.run(accuracy, feed_dict={x: mnist.train.images[:10000], y: mnist.train.labels[:10000],keep_prob: 1.0}) print("Iter " + str(i) + ", Testing Accuracy= " + str(test_acc) + ", Training Accuracy= " + str(train_acc))