Keras mlp 手写数字识别示例

#基于mnist数据集的手写数字识别

#构造了三层全连接层组成的多层感知机，最后一层为输出层

#基于Keras 2.1.1 Tensorflow 1.4.0

代码：

 import keras
 from keras.datasets import mnist
 from keras.models import Sequential
 from keras.layers import Dense,Dropout
 from keras.optimizers import RMSprop

 (x_train,y_train),(x_test,y_test) = mnist.load_data()
 #载入数据，第一次运行时会从外部网络下载数据集到对应目录下
 print(x_train.shape,y_train.shape)
 print(x_test.shape,y_test.shape)

 # import matplotlib.pyplot as plt
 # im = plt.imshow(x_train[0],cmap='gray')
 # plt.show()
 # im2 = plt.imshow(x_train[1],cmap='gray')
 # plt.show()
 x_train = x_train.reshape(60000,784)
 x_test = x_test.reshape(10000,784)
 x_train = x_train.astype('float32')
 x_train = x_train.astype('float32')
 print(x_train.shape)
 x_train = x_train/255
 x_test = x_test/255
 y_train = keras.utils.to_categorical(y_train,10)
 y_test = keras.utils.to_categorical(y_test,10)

 model = Sequential()
 model.add(Dense(512,activation='relu',input_shape=(784,)))
 model.add(Dropout(0.2))
 model.add(Dense(512,activation='relu'))
 model.add(Dropout(0.2))
 model.add(Dense(10,activation='softmax'))
 model.summary()
 model.compile(loss='categorical_crossentropy',optimizer=RMSprop(),metrics=['accuracy'])
 model.fit(x_train,y_train,batch_size=64,epochs=2,verbose=1,validation_data=(x_test,y_test))
 score = model.evaluate(x_test,y_test,verbose=1)
 print('Test loss:',score[0])
 print('Test accuracy',score[1])

结果：

Test loss: 0.123420921481
Test accuracy 0.9682