tensorflow手写数据集分类
所使用的环境及数据集;
tensorflow 1.15.0
本地MNIST数据包
以下为代码
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)
# 批次大小
batch_size = 64
# 计算一个周期一共有多少个批次
n_batch = mnist.train.num_examples // batch_size
# 定义两个placeholder
x = tf.placeholder(tf.float32,[None,784])
y = tf.placeholder(tf.float32,[None,10])
# 创建一个简单的神经网络:784-10
W = tf.Variable(tf.truncated_normal([784,10], stddev=0.1))
b = tf.Variable(tf.zeros([10]) + 0.1)
prediction = tf.nn.softmax(tf.matmul(x,W)+b)
# 二次代价函数
loss = tf.losses.mean_squared_error(y, prediction)
# 使用梯度下降法
train = tf.train.GradientDescentOptimizer(0.3).minimize(loss)
# 结果存放在一个布尔型列表中
correct_prediction = tf.equal(tf.argmax(y,1),tf.argmax(prediction,1))
# 求准确率
accuracy = tf.reduce_mean(tf.cast(correct_prediction,tf.float32))
with tf.Session() as sess:
# 变量初始化
sess.run(tf.global_variables_initializer())
# 周期epoch:所有数据训练一次,就是一个周期
for epoch in range(21):
for batch in range(n_batch):
# 获取一个批次的数据和标签
batch_xs,batch_ys = mnist.train.next_batch(batch_size)
sess.run(train,feed_dict={x:batch_xs,y:batch_ys})
# 每训练一个周期做一次测试
acc = sess.run(accuracy,feed_dict={x:mnist.test.images,y:mnist.test.labels})
print("Iter " + str(epoch) + ",Testing Accuracy " + str(acc))
keras手写数据集分类
import numpy as np
from keras.datasets import mnist
from keras.utils import np_utils
from keras.models import Sequential
from keras.layers import Dense
from keras.optimizers import SGD
# 载入数据
(x_train,y_train),(x_test,y_test) = mnist.load_data()
# (60000,28,28)
print('x_shape:',x_train.shape)
# (60000)
print('y_shape:',y_train.shape)
# (60000,28,28)->(60000,784)
x_train = x_train.reshape(x_train.shape[0],-1)/255.0
x_test = x_test.reshape(x_test.shape[0],-1)/255.0
# 讲标签转换为one hot格式(即独热编码格式)
y_train = np_utils.to_categorical(y_train,num_classes=10)
y_test = np_utils.to_categorical(y_test,num_classes=10)
# 创建模型,输入784个神经元,输出10个神经元
model = Sequential([
Dense(units=10,input_dim=784,bias_initializer='one',activation='softmax')
])
# 定义优化器
sgd = SGD(lr=0.2)
# 定义优化器,loss function,训练过程中计算准确率
model.compile(
optimizer = sgd,
loss = 'mse',
metrics=['accuracy'],
)
# 训练模型
model.fit(x_train,y_train,batch_size=32,epochs=10)
# 评估模型
loss,accuracy = model.evaluate(x_test,y_test)
print('\ntest loss',loss)
print('accuracy',accuracy)