深度残差收缩网络总结
1. 深度残差收缩网络的初衷
大家有没有发现这样一种现象：在很多数据集中，每个样本内部，都或多或少地包含着一些与标签无关的信息；这些信息的话，其实就是冗余的。
然后，即使在同一个样本集中，各个样本的噪声含量也往往是不同的。
那么，降噪算法中常用的软阈值函数，能不能嵌入到深度残差网络中呢？
2. 深度残差收缩网络的结构
深度残差收缩网络本质上就是深度残差网络和软阈值函数的集成。不仅如此，软阈值函数所需要的阈值，也是在深度残差收缩网络内部自动设置的，避免了人工设置的麻烦。深度残差收缩网络的基本模块如下图所示：
通过堆叠许多基本模块以及输入层和全连接输出层，我们就可以得到深度残差收缩网络的整体结构：
3.深度残差收缩网络的实现
下面以图像分类为例，构建了一个小型的深度残差收缩网络，超参数也没有优化。为追求高准确率的话，可以适当增加深度，增加训练迭代次数，以及适当调整超参数。下面是Keras程序：
#!/usr/bin/env python3 # -*- coding: utf-8 -*- """ Created on Sat Dec 28 23:24:05 2019 Implemented using TensorFlow 1.0.1 and Keras 2.2.1 M. Zhao, S. Zhong, X. Fu, et al., Deep Residual Shrinkage Networks for Fault Diagnosis, IEEE Transactions on Industrial Informatics, 2019, DOI: 10.1109/TII.2019.2943898 @author: super_9527 """ from __future__ import print_function import keras import numpy as np from keras.datasets import mnist from keras.layers import Dense, Conv2D, BatchNormalization, Activation from keras.layers import AveragePooling2D, Input, GlobalAveragePooling2D from keras.optimizers import Adam from keras.regularizers import l2 from keras import backend as K from keras.models import Model from keras.layers.core import Lambda K.set_learning_phase(1) # Input image dimensions img_rows, img_cols = 28, 28 # The data, split between train and test sets (x_train, y_train), (x_test, y_test) = mnist.load_data() if K.image_data_format() == 'channels_first': x_train = x_train.reshape(x_train.shape[0], 1, img_rows, img_cols) x_test = x_test.reshape(x_test.shape[0], 1, img_rows, img_cols) input_shape = (1, img_rows, img_cols) else: x_train = x_train.reshape(x_train.shape[0], img_rows, img_cols, 1) x_test = x_test.reshape(x_test.shape[0], img_rows, img_cols, 1) input_shape = (img_rows, img_cols, 1) # Noised data x_train = x_train.astype('float32') / 255. + 0.5*np.random.random([x_train.shape[0], img_rows, img_cols, 1]) x_test = x_test.astype('float32') / 255. + 0.5*np.random.random([x_test.shape[0], img_rows, img_cols, 1]) print('x_train shape:', x_train.shape) print(x_train.shape[0], 'train samples') print(x_test.shape[0], 'test samples') # convert class vectors to binary class matrices y_train = keras.utils.to_categorical(y_train, 10) y_test = keras.utils.to_categorical(y_test, 10) def abs_backend(inputs): return K.abs(inputs) def expand_dim_backend(inputs): return K.expand_dims(K.expand_dims(inputs,1),1) def sign_backend(inputs): return K.sign(inputs) def pad_backend(inputs, in_channels, out_channels): pad_dim = (out_channels - in_channels)//2 return K.spatial_3d_padding(inputs, padding = ((0,0),(0,0),(pad_dim,pad_dim))) # Residual Shrinakge Block def residual_shrinkage_block(incoming, nb_blocks, out_channels, downsample=False, downsample_strides=2): residual = incoming in_channels = incoming.get_shape().as_list()[-1] for i in range(nb_blocks): identity = residual if not downsample: downsample_strides = 1 residual = BatchNormalization()(residual) residual = Activation('relu')(residual) residual = Conv2D(out_channels, 3, strides=(downsample_strides, downsample_strides), padding='same', kernel_initializer='he_normal', kernel_regularizer=l2(1e-4))(residual) residual = BatchNormalization()(residual) residual = Activation('relu')(residual) residual = Conv2D(out_channels, 3, padding='same', kernel_initializer='he_normal', kernel_regularizer=l2(1e-4))(residual) # Calculate global means residual_abs = Lambda(abs_backend)(residual) abs_mean = GlobalAveragePooling2D()(residual_abs) # Calculate scaling coefficients scales = Dense(out_channels, activation=None, kernel_initializer='he_normal', kernel_regularizer=l2(1e-4))(abs_mean) scales = BatchNormalization()(scales) scales = Activation('relu')(scales) scales = Dense(out_channels, activation='sigmoid', kernel_regularizer=l2(1e-4))(scales) scales = Lambda(expand_dim_backend)(scales) # Calculate thresholds thres = keras.layers.multiply([abs_mean, scales]) # Soft thresholding sub = keras.layers.subtract([residual_abs, thres]) zeros = keras.layers.subtract([sub, sub]) n_sub = keras.layers.maximum([sub, zeros]) residual = keras.layers.multiply([Lambda(sign_backend)(residual), n_sub]) # Downsampling (it is important to use the pooL-size of (1, 1)) if downsample_strides > 1: identity = AveragePooling2D(pool_size=(1,1), strides=(2,2))(identity) # Zero_padding to match channels (it is important to use zero padding rather than 1by1 convolution) if in_channels != out_channels: identity = Lambda(pad_backend)(identity, in_channels, out_channels) residual = keras.layers.add([residual, identity]) return residual # define and train a model inputs = Input(shape=input_shape) net = Conv2D(8, 3, padding='same', kernel_initializer='he_normal', kernel_regularizer=l2(1e-4))(inputs) net = residual_shrinkage_block(net, 1, 8, downsample=True) net = BatchNormalization()(net) net = Activation('relu')(net) net = GlobalAveragePooling2D()(net) outputs = Dense(10, activation='softmax', kernel_initializer='he_normal', kernel_regularizer=l2(1e-4))(net) model = Model(inputs=inputs, outputs=outputs) model.compile(loss='categorical_crossentropy', optimizer=Adam(), metrics=['accuracy']) model.fit(x_train, y_train, batch_size=100, epochs=5, verbose=1, validation_data=(x_test, y_test)) # get results K.set_learning_phase(0) DRSN_train_score = model.evaluate(x_train, y_train, batch_size=100, verbose=0) print('Train loss:', DRSN_train_score[0]) print('Train accuracy:', DRSN_train_score[1]) DRSN_test_score = model.evaluate(x_test, y_test, batch_size=100, verbose=0) print('Test loss:', DRSN_test_score[0]) print('Test accuracy:', DRSN_test_score[1])
TFLearn程序：
#!/usr/bin/env python3 # -*- coding: utf-8 -*- """ Created on Mon Dec 23 21:23:09 2019 Implemented using TensorFlow 1.0 and TFLearn 0.3.2 M. Zhao, S. Zhong, X. Fu, B. Tang, M. Pecht, Deep Residual Shrinkage Networks for Fault Diagnosis, IEEE Transactions on Industrial Informatics, 2019, DOI: 10.1109/TII.2019.2943898 @author: super_9527 """ from __future__ import division, print_function, absolute_import import tflearn import numpy as np import tensorflow as tf from tflearn.layers.conv import conv_2d # Data loading from tflearn.datasets import cifar10 (X, Y), (testX, testY) = cifar10.load_data() # Add noise X = X + np.random.random((50000, 32, 32, 3))*0.1 testX = testX + np.random.random((10000, 32, 32, 3))*0.1 # Transform labels to one-hot format Y = tflearn.data_utils.to_categorical(Y,10) testY = tflearn.data_utils.to_categorical(testY,10) def residual_shrinkage_block(incoming, nb_blocks, out_channels, downsample=False, downsample_strides=2, activation='relu', batch_norm=True, bias=True, weights_init='variance_scaling', bias_init='zeros', regularizer='L2', weight_decay=0.0001, trainable=True, restore=True, reuse=False, scope=None, name="ResidualBlock"): # residual shrinkage blocks with channel-wise thresholds residual = incoming in_channels = incoming.get_shape().as_list()[-1] # Variable Scope fix for older TF try: vscope = tf.variable_scope(scope, default_name=name, values=[incoming], reuse=reuse) except Exception: vscope = tf.variable_op_scope([incoming], scope, name, reuse=reuse) with vscope as scope: name = scope.name #TODO for i in range(nb_blocks): identity = residual if not downsample: downsample_strides = 1 if batch_norm: residual = tflearn.batch_normalization(residual) residual = tflearn.activation(residual, activation) residual = conv_2d(residual, out_channels, 3, downsample_strides, 'same', 'linear', bias, weights_init, bias_init, regularizer, weight_decay, trainable, restore) if batch_norm: residual = tflearn.batch_normalization(residual) residual = tflearn.activation(residual, activation) residual = conv_2d(residual, out_channels, 3, 1, 'same', 'linear', bias, weights_init, bias_init, regularizer, weight_decay, trainable, restore) # get thresholds and apply thresholding abs_mean = tf.reduce_mean(tf.reduce_mean(tf.abs(residual),axis=2,keep_dims=True),axis=1,keep_dims=True) scales = tflearn.fully_connected(abs_mean, out_channels//4, activation='linear',regularizer='L2',weight_decay=0.0001,weights_init='variance_scaling') scales = tflearn.batch_normalization(scales) scales = tflearn.activation(scales, 'relu') scales = tflearn.fully_connected(scales, out_channels, activation='linear',regularizer='L2',weight_decay=0.0001,weights_init='variance_scaling') scales = tf.expand_dims(tf.expand_dims(scales,axis=1),axis=1) thres = tf.multiply(abs_mean,tflearn.activations.sigmoid(scales)) # soft thresholding residual = tf.multiply(tf.sign(residual), tf.maximum(tf.abs(residual)-thres,0)) # Downsampling if downsample_strides > 1: identity = tflearn.avg_pool_2d(identity, 1, downsample_strides) # Projection to new dimension if in_channels != out_channels: if (out_channels - in_channels) % 2 == 0: ch = (out_channels - in_channels)//2 identity = tf.pad(identity, [[0, 0], [0, 0], [0, 0], [ch, ch]]) else: ch = (out_channels - in_channels)//2 identity = tf.pad(identity, [[0, 0], [0, 0], [0, 0], [ch, ch+1]]) in_channels = out_channels residual = residual + identity return residual # Real-time data preprocessing img_prep = tflearn.ImagePreprocessing() img_prep.add_featurewise_zero_center(per_channel=True) # Real-time data augmentation img_aug = tflearn.ImageAugmentation() img_aug.add_random_flip_leftright() img_aug.add_random_crop([32, 32], padding=4) # Build a Deep Residual Shrinkage Network with 3 blocks net = tflearn.input_data(shape=[None, 32, 32, 3], data_preprocessing=img_prep, data_augmentation=img_aug) net = tflearn.conv_2d(net, 16, 3, regularizer='L2', weight_decay=0.0001) net = residual_shrinkage_block(net, 1, 16) net = residual_shrinkage_block(net, 1, 32, downsample=True) net = residual_shrinkage_block(net, 1, 32, downsample=True) net = tflearn.batch_normalization(net) net = tflearn.activation(net, 'relu') net = tflearn.global_avg_pool(net) # Regression net = tflearn.fully_connected(net, 10, activation='softmax') mom = tflearn.Momentum(0.1, lr_decay=0.1, decay_step=20000, staircase=True) net = tflearn.regression(net, optimizer=mom, loss='categorical_crossentropy') # Training model = tflearn.DNN(net, checkpoint_path='model_cifar10', max_checkpoints=10, tensorboard_verbose=0, clip_gradients=0.) model.fit(X, Y, n_epoch=100, snapshot_epoch=False, snapshot_step=500, show_metric=True, batch_size=100, shuffle=True, run_id='model_cifar10') training_acc = model.evaluate(X, Y)[0] validation_acc = model.evaluate(testX, testY)[0]
M. Zhao, S. Zhong, X. Fu, et al. Deep residual shrinkage networks for fault diagnosis[J]. IEEE Transactions on Industrial Informatics, DOI: 10.1109/TII.2019.2943898
