【Keras】使用Keras建立模型并训练等一系列操作

由于Keras是一种建立在已有深度学习框架上的二次框架，其使用起来非常方便，其后端实现有两种方法，theano和tensorflow。由于自己平时用tensorflow，所以选择后端用tensorflow的Keras，代码写起来更加方便。

1、建立模型

Keras分为两种不同的建模方式，

Sequential models：这种方法用于实现一些简单的模型。你只需要向一些存在的模型中添加层就行了。

Functional API：Keras的API是非常强大的，你可以利用这些API来构造更加复杂的模型，比如多输出模型，有向无环图等等。

这里采用sequential models方法。

构建序列模型。

def define_model():

model = Sequential()

# setup first conv layer
model.add(Conv2D(32, (3, 3), activation="relu",
input_shape=(120, 120, 3), padding='same'))  # [10, 120, 120, 32]

# setup first maxpooling layer
model.add(MaxPooling2D(pool_size=(2, 2)))  # [10, 60, 60, 32]

# setup second conv layer
model.add(Conv2D(8, kernel_size=(3, 3), activation="relu",
padding='same'))  # [10, 60, 60, 8]

# setup second maxpooling layer
model.add(MaxPooling2D(pool_size=(3, 3)))  # [10, 20, 20, 8]

# add bianping layer, 3200 = 20 * 20 * 8
model.add(Flatten())  # [10, 3200]

# add first full connection layer
model.add(Dense(512, activation='sigmoid'))  # [10, 512]

# add dropout layer
model.add(Dropout(0.5))

# add second full connection layer
model.add(Dense(4, activation='softmax'))  # [10, 4]

return model

可以看到定义模型时输出的网络结构。

2、准备数据

def load_data(resultpath):
datapath = os.path.join(resultpath, "data10_4.npz")
if os.path.exists(datapath):
data = np.load(datapath)
X, Y = data["X"], data["Y"]
else:
X = np.array(np.arange(432000)).reshape(10, 120, 120, 3)
Y = [0, 0, 1, 1, 2, 2, 3, 3, 2, 0]
X = X.astype('float32')
Y = np_utils.to_categorical(Y, 4)
np.savez(datapath, X=X, Y=Y)
print('Saved dataset to dataset.npz.')
print('X_shape:{}\nY_shape:{}'.format(X.shape, Y.shape))
return X, Y

3、训练模型

def train_model(resultpath):
model = define_model()

# if want to use SGD, first define sgd, then set optimizer=sgd
sgd = SGD(lr=0.001, decay=1e-6, momentum=0, nesterov=True)

# select loss\optimizer\
model.compile(loss=categorical_crossentropy,
optimizer=Adam(), metrics=['accuracy'])
model.summary()

# draw the model structure
plot_model(model, show_shapes=True,
to_file=os.path.join(resultpath, 'model.png'))

# load data
X, Y = load_data(resultpath)

# split train and test data
X_train, X_test, Y_train, Y_test = train_test_split(
X, Y, test_size=0.2, random_state=2)

# input data to model and train
history = model.fit(X_train, Y_train, batch_size=2, epochs=10,
validation_data=(X_test, Y_test), verbose=1, shuffle=True)

# evaluate the model
loss, acc = model.evaluate(X_test, Y_test, verbose=0)
print('Test loss:', loss)
print('Test accuracy:', acc)

可以看到训练时输出的日志。因为是随机数据，没有意义，这里训练的结果不必计较，只是练习而已。



保存下来的模型结构：

4、保存与加载模型并测试

有两种保存方式

4.1 直接保存模型h5

保存：

def my_save_model(resultpath):

model = train_model(resultpath)

# the first way to save model
model.save(os.path.join(resultpath, 'my_model.h5'))

加载：

def my_load_model(resultpath):

# test data
X = np.array(np.arange(86400)).reshape(2, 120, 120, 3)
Y = [0, 1]
X = X.astype('float32')
Y = np_utils.to_categorical(Y, 4)

# the first way of load model
model2 = load_model(os.path.join(resultpath, 'my_model.h5'))
model2.compile(loss=categorical_crossentropy,
optimizer=Adam(), metrics=['accuracy'])

test_loss, test_acc = model2.evaluate(X, Y, verbose=0)
print('Test loss:', test_loss)
print('Test accuracy:', test_acc)

y = model2.predict_classes(X)
print("predicct is: ", y)

4.2 分别保存网络结构和权重

保存：

def my_save_model(resultpath):

model = train_model(resultpath)

# the secon way : save trained network structure and weights
model_json = model.to_json()
open(os.path.join(resultpath, 'my_model_structure.json'), 'w').write(model_json)
model.save_weights(os.path.join(resultpath, 'my_model_weights.hd5'))

加载：

def my_load_model(resultpath):

# test data
X = np.array(np.arange(86400)).reshape(2, 120, 120, 3)
Y = [0, 1]
X = X.astype('float32')
Y = np_utils.to_categorical(Y, 4)

# the second way : load model structure and weights
model = model_from_json(open(os.path.join(resultpath, 'my_model_structure.json')).read())
model.load_weights(os.path.join(resultpath, 'my_model_weights.hd5'))
model.compile(loss=categorical_crossentropy,
optimizer=Adam(), metrics=['accuracy'])

test_loss, test_acc = model.evaluate(X, Y, verbose=0)
print('Test loss:', test_loss)
print('Test accuracy:', test_acc)

y = model.predict_classes(X)
print("predicct is: ", y)

可以看到，两次的结果是一样的。

5、完整代码

from keras.models import Sequential
from keras.layers import Dense, Conv2D, MaxPooling2D, Flatten, Dropout
from keras.losses import categorical_crossentropy
from keras.optimizers import Adam
from keras.utils.vis_utils import plot_model
from keras.optimizers import SGD
from keras.models import model_from_json
from keras.models import load_model
from keras.utils import np_utils
import numpy as np
import os
from sklearn.model_selection import train_test_split

def load_data(resultpath):
datapath = os.path.join(resultpath, "data10_4.npz")
if os.path.exists(datapath):
data = np.load(datapath)
X, Y = data["X"], data["Y"]
else:
X = np.array(np.arange(432000)).reshape(10, 120, 120, 3)
Y = [0, 0, 1, 1, 2, 2, 3, 3, 2, 0]
X = X.astype('float32')
Y = np_utils.to_categorical(Y, 4)
np.savez(datapath, X=X, Y=Y)
print('Saved dataset to dataset.npz.')
print('X_shape:{}\nY_shape:{}'.format(X.shape, Y.shape))
return X, Y

def define_model():
model = Sequential()

# setup first conv layer
model.add(Conv2D(32, (3, 3), activation="relu",
input_shape=(120, 120, 3), padding='same'))  # [10, 120, 120, 32]

# setup first maxpooling layer
model.add(MaxPooling2D(pool_size=(2, 2)))  # [10, 60, 60, 32]

# setup second conv layer
model.add(Conv2D(8, kernel_size=(3, 3), activation="relu",
padding='same'))  # [10, 60, 60, 8]

# setup second maxpooling layer
model.add(MaxPooling2D(pool_size=(3, 3)))  # [10, 20, 20, 8]

# add bianping layer, 3200 = 20 * 20 * 8
model.add(Flatten())  # [10, 3200]

# add first full connection layer
model.add(Dense(512, activation='sigmoid'))  # [10, 512]

# add dropout layer
model.add(Dropout(0.5))

# add second full connection layer
model.add(Dense(4, activation='softmax'))  # [10, 4]

return model

def train_model(resultpath):
model = define_model()

# if want to use SGD, first define sgd, then set optimizer=sgd
sgd = SGD(lr=0.001, decay=1e-6, momentum=0, nesterov=True)

# select loss\optimizer\
model.compile(loss=categorical_crossentropy,
optimizer=Adam(), metrics=['accuracy'])
model.summary()

# draw the model structure
plot_model(model, show_shapes=True,
to_file=os.path.join(resultpath, 'model.png'))

# load data
X, Y = load_data(resultpath)

# split train and test data
X_train, X_test, Y_train, Y_test = train_test_split(
X, Y, test_size=0.2, random_state=2)

# input data to model and train
history = model.fit(X_train, Y_train, batch_size=2, epochs=10,
validation_data=(X_test, Y_test), verbose=1, shuffle=True)

# evaluate the model
loss, acc = model.evaluate(X_test, Y_test, verbose=0)
print('Test loss:', loss)
print('Test accuracy:', acc)

return model

def my_save_model(resultpath):

model = train_model(resultpath)

# the first way to save model
model.save(os.path.join(resultpath, 'my_model.h5'))
# the secon way : save trained network structure and weights
model_json = model.to_json()
open(os.path.join(resultpath, 'my_model_structure.json'), 'w').write(model_json)
model.save_weights(os.path.join(resultpath, 'my_model_weights.hd5'))

def my_load_model(resultpath):

# test data
X = np.array(np.arange(86400)).reshape(2, 120, 120, 3)
Y = [0, 1]
X = X.astype('float32')
Y = np_utils.to_categorical(Y, 4)

# the first way of load model
model2 = load_model(os.path.join(resultpath, 'my_model.h5'))
model2.compile(loss=categorical_crossentropy,
optimizer=Adam(), metrics=['accuracy'])

test_loss, test_acc = model2.evaluate(X, Y, verbose=0)
print('Test loss:', test_loss)
print('Test accuracy:', test_acc)

y = model2.predict_classes(X)
print("predicct is: ", y)

# the second way : load model structure and weights
model = model_from_json(open(os.path.join(resultpath, 'my_model_structure.json')).read())
model.load_weights(os.path.join(resultpath, 'my_model_weights.hd5'))
model.compile(loss=categorical_crossentropy,
optimizer=Adam(), metrics=['accuracy'])

test_loss, test_acc = model.evaluate(X, Y, verbose=0)
print('Test loss:', test_loss)
print('Test accuracy:', test_acc)

y = model.predict_classes(X)
print("predicct is: ", y)

def main():
resultpath = "result"
#train_model(resultpath)
#my_save_model(resultpath)
my_load_model(resultpath)

if __name__ == "__main__":
main()