Alexnet

"""
	AlexNet Keras implementation
	"""
	# Import necessary libs
	import os
	from keras.models import Model
	from keras.layers import Conv2D, MaxPool2D, ZeroPadding2D, Dense, Dropout, \
	Activation, Flatten, BatchNormalization, Input
	from keras.regularizers import l2
	from keras.preprocessing.image import ImageDataGenerator
	from keras.utils import multi_gpu_model
	from keras.callbacks import TensorBoard, EarlyStopping
	import math
	os.environ["CUDA_VISIBLE_DEVICES"] = "2, 3"
	def AlexNet(input_shape=(224, 224, 3), num_classes=10, l2_reg=0.0, weights=None):
	"""
	AlexNet model
	:param input_shape: input shape
	:param num_classes: the number of classes
	:param l2_reg:
	:param weights:
	:return: model
	"""
	input_layer = Input(shape=input_shape)
	# Layer 1
	# In order to get the same size of the paper mentioned, add padding layer first
	x = ZeroPadding2D(padding=(2, 2))(input_layer)
	x = conv_block(x, filters=96, kernel_size=(11, 11),
	strides=(4, 4), padding="valid", l2_reg=l2_reg, name='Conv_1_96_11x11_4')
	x = MaxPool2D(pool_size=(3, 3), strides=(2, 2), padding="valid", name="maxpool_1_3x3_2")(x)
	# Layer 2
	x = conv_block(x, filters=256, kernel_size=(5, 5),
	strides=(1, 1), padding="same", l2_reg=l2_reg, name="Conv_2_256_5x5_1")
	x = MaxPool2D(pool_size=(3, 3), strides=(2, 2), padding="valid", name="maxpool_2_3x3_2")(x)
	# Layer 3
	x = conv_block(x, filters=384, kernel_size=(3, 3),
	strides=(1, 1), padding="same", l2_reg=l2_reg, name="Conv_3_384_3x3_1")
	# Layer 4
	x = conv_block(x, filters=384, kernel_size=(3, 3),
	strides=(1, 1), padding="same", l2_reg=l2_reg, name="Conv_4_384_3x3_1")
	# Layer 5
	x = conv_block(x, filters=256, kernel_size=(3, 3),
	strides=(1, 1), padding="same", l2_reg=l2_reg, name="Conv_5_256_3x3_1")
	x = MaxPool2D(pool_size=(3, 3), strides=(2, 2), padding="valid", name="maxpool_3_3x3_2")(x)
	# Layer 6
	x = Flatten()(x)
	x = Dense(units=4096)(x)
	x = BatchNormalization()(x)
	x = Activation('relu')(x)
	# Layer 7
	x = Dense(units=4096)(x)
	x = BatchNormalization()(x)
	x = Activation('relu')(x)
	# Layer 8
	x = Dense(units=num_classes)(x)
	x = BatchNormalization()(x)
	x = Activation("softmax")(x)
	if weights is not None:
	x.load_weights(weights)
	model = Model(input_layer, x, name="AlexNet")
	return model
	def conv_block(layer, filters, kernel_size=(3, 3), strides=(1, 1), padding='valid', l2_reg=0.0, name=None):
	x = Conv2D(filters=filters,
	kernel_size=kernel_size,
	strides=strides,
	padding=padding,
	kernel_regularizer=l2(l2_reg),
	kernel_initializer="he_normal",
	name=name)(layer)
	x = BatchNormalization()(x)
	x = Activation('relu')(x)
	return x
	input_shape = (224, 224, 3)
	num_classes = 10
	alexnet = AlexNet(input_shape=input_shape, num_classes=num_classes)
	alexnet.summary()
	parallel_model = multi_gpu_model(alexnet, gpus=2)
	epochs = 200
	model_name = "AlexNet-2"
	train_dir = r'/home/lst/datasets/cifar-10-images_train/'
	test_dir = r'/home/lst/datasets/cifar-10-images_test/'
	batch_size = 256
	target_weight_height = (224, 224)
	parallel_model.compile(loss=['categorical_crossentropy'],
	optimizer='adadelta',
	metrics=["accuracy"])
	tensorboard = TensorBoard(log_dir=f'./logs/{model_name}', histogram_freq=0,
	write_graph=True, write_images=False)
	early_stopping = EarlyStopping(monitor='val_loss', patience=20, verbose=1)
	train_datagen = ImageDataGenerator(
	rotation_range=40,
	width_shift_range=0.2,
	height_shift_range=0.2,
	rescale=1. / 255,
	shear_range=0.2,
	zoom_range=0.2,
	horizontal_flip=True,
	fill_mode="nearest")
	test_datagen = ImageDataGenerator(rescale=1. / 255)
	train_generator = train_datagen.flow_from_directory(
	train_dir,
	target_size=target_weight_height,
	batch_size=batch_size,
	class_mode='categorical')
	validation_generator = test_datagen.flow_from_directory(
	test_dir,
	target_size=target_weight_height,
	batch_size=batch_size,
	class_mode='categorical')
	num_train_samples = train_generator.samples
	num_val_samples = validation_generator.samples
	history = parallel_model.fit_generator(train_generator,
	validation_data=validation_generator,
	steps_per_epoch=math.ceil(num_train_samples / batch_size),
	validation_steps=math.ceil(num_val_samples / batch_size),
	epochs=epochs,
	callbacks=[tensorboard, early_stopping],
	)
	parallel_model.save(f"{model_name}.h5")

来源：https://www.cnblogs.com/sun-321/p/11919616.html