用keras实现Resnet50
时间: 2024-05-06 12:15:56 浏览: 111
好的,以下是使用Keras实现ResNet50的示例代码:
```
from keras.layers import Input, Conv2D, MaxPooling2D, AveragePooling2D, Flatten, Dense, BatchNormalization, Activation, ZeroPadding2D
from keras.models import Model
from keras.initializers import glorot_uniform
def identity_block(X, f, filters, stage, block):
"""
实现恒等块
参数:
X - 输入的tensor类型的数据,维度为( m, n_H_prev, n_W_prev, n_H_prev )
f - 整数,指定主路径中间的CONV窗口的维度
filters - 整数列表,定义了主路径每层的卷积核数量
stage - 整数,根据每层的位置来命名每一层,与block参数一起使用。
block - 字符串,根据每层的位置来命名每一层,与stage参数一起使用。
返回:
X - 恒等块的输出,tensor类型,维度为(n_H, n_W, n_C)
"""
# 定义命名规则
conv_name_base = 'res' + str(stage) + block + '_branch'
bn_name_base = 'bn' + str(stage) + block + '_branch'
# 获取过滤器
F1, F2, F3 = filters
# 保存输入数据,将会用于为主路径添加捷径
X_shortcut = X
# 主路径的第一部分
X = Conv2D(filters=F1, kernel_size=(1, 1), strides=(1, 1), padding='valid',
name=conv_name_base + '2a', kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name=bn_name_base + '2a')(X)
X = Activation('relu')(X)
# 主路径的第二部分
X = Conv2D(filters=F2, kernel_size=(f, f), strides=(1, 1), padding='same',
name=conv_name_base + '2b', kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name=bn_name_base + '2b')(X)
X = Activation('relu')(X)
# 主路径的第三部分
X = Conv2D(filters=F3, kernel_size=(1, 1), strides=(1, 1), padding='valid',
name=conv_name_base + '2c', kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name=bn_name_base + '2c')(X)
# 主路径的最后一步:添加捷径值,并通过ReLU激活函数进行处理
X = Add()([X, X_shortcut])
X = Activation('relu')(X)
return X
def convolutional_block(X, f, filters, stage, block, s=2):
"""
实现卷积块
参数:
X - 输入的tensor类型的数据,维度为( m, n_H_prev, n_W_prev, n_H_prev )
f - 整数,指定主路径中间的CONV窗口的维度
filters - 整数列表,定义了主路径每层的卷积核数量
stage - 整数,根据每层的位置来命名每一层,与block参数一起使用。
block - 字符串,根据每层的位置来命名每一层,与stage参数一起使用。
s - 整数,指定要使用的步幅
返回:
X - 卷积块的输出,tensor类型,维度为(n_H, n_W, n_C)
"""
# 定义命名规则
conv_name_base = 'res' + str(stage) + block + '_branch'
bn_name_base = 'bn' + str(stage) + block + '_branch'
# 获取过滤器
F1, F2, F3 = filters
# 保存输入数据,将会用于为主路径添加捷径
X_shortcut = X
# 主路径的第一部分
X = Conv2D(filters=F1, kernel_size=(1, 1), strides=(s, s), padding='valid',
name=conv_name_base + '2a', kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name=bn_name_base + '2a')(X)
X = Activation('relu')(X)
# 主路径的第二部分
X = Conv2D(filters=F2, kernel_size=(f, f), strides=(1, 1), padding='same',
name=conv_name_base + '2b', kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name=bn_name_base + '2b')(X)
X = Activation('relu')(X)
# 主路径的第三部分
X = Conv2D(filters=F3, kernel_size=(1, 1), strides=(1, 1), padding='valid',
name=conv_name_base + '2c', kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name=bn_name_base + '2c')(X)
# 捷径路径
X_shortcut = Conv2D(filters=F3, kernel_size=(1, 1), strides=(s, s), padding='valid',
name=conv_name_base + '1', kernel_initializer=glorot_uniform(seed=0))(X_shortcut)
X_shortcut = BatchNormalization(axis=3, name=bn_name_base + '1')(X_shortcut)
# 主路径的最后一步:添加捷径值,并通过ReLU激活函数进行处理
X = Add()([X, X_shortcut])
X = Activation('relu')(X)
return X
def ResNet50(input_shape=(64, 64, 3), classes=6):
"""
实现ResNet50
参数:
input_shape - 输入数据的维度
classes - 分类数
返回:
model - Keras框架的模型
"""
# 定义输入为维度为input_shape的tensor
X_input = Input(input_shape)
# 使用0填充:X_input的周围填充0,填充量为3
X = ZeroPadding2D((3, 3))(X_input)
# 第1阶段
X = Conv2D(filters=64, kernel_size=(7, 7), strides=(2, 2), name='conv1',
kernel_initializer=glorot_uniform(seed=0))(X)
X = BatchNormalization(axis=3, name='bn_conv1')(X)
X = Activation('relu')(X)
X = MaxPooling2D(pool_size=(3, 3), strides=(2, 2))(X)
# 第2阶段
X = convolutional_block(X, f=3, filters=[64, 64, 256], stage=2, block='a', s=1)
X = identity_block(X, f=3, filters=[64, 64, 256], stage=2, block='b')
X = identity_block(X, f=3, filters=[64, 64, 256], stage=2, block='c')
# 第3阶段
X = convolutional_block(X, f=3, filters=[128, 128, 512], stage=3, block='a', s=2)
X = identity_block(X, f=3, filters=[128, 128, 512], stage=3, block='b')
X = identity_block(X, f=3, filters=[128, 128, 512], stage=3, block='c')
X = identity_block(X, f=3, filters=[128, 128, 512], stage=3, block='d')
# 第4阶段
X = convolutional_block(X, f=3, filters=[256, 256, 1024], stage=4, block='a', s=2)
X = identity_block(X, f=3, filters=[256, 256, 1024], stage=4, block='b')
X = identity_block(X, f=3, filters=[256, 256, 1024], stage=4, block='c')
X = identity_block(X, f=3, filters=[256, 256, 1024], stage=4, block='d')
X = identity_block(X, f=3, filters=[256, 256, 1024], stage=4, block='e')
X = identity_block(X, f=3, filters=[256, 256, 1024], stage=4, block='f')
# 第5阶段
X = convolutional_block(X, f=3, filters=[512, 512, 2048], stage=5, block='a', s=2)
X = identity_block(X, f=3, filters=[512, 512, 2048], stage=5, block='b')
X = identity_block(X, f=3, filters=[512, 512, 2048], stage=5, block='c')
# 平均池化层
X = AveragePooling2D(pool_size=(2, 2), padding='same')(X)
# 输出层
X = Flatten()(X)
X = Dense(classes, activation='softmax', name='fc' + str(classes),
kernel_initializer=glorot_uniform(seed=0))(X)
# 创建模型
model = Model(inputs=X_input, outputs=X, name='ResNet50')
return model
```
以上代码实现了ResNet50模型,包括了卷积块、恒等块、输入层、输出层等组件。可以使用该代码构建一个ResNet50模型并进行训练。
阅读全文