信号处理--基于单通道脑电信号EEG的睡眠分期评估

背景

睡眠对人体健康很重要。监测人体的睡眠分期对于人体健康和医疗具有重要意义。

亮点

架构在第一层使用两个具有不同滤波器大小的 CNN 和双向 LSTM。 CNN 可以被训练来学习滤波器，以从原始单通道 EEG 中提取时不变特征，而双向 LSTM 可以被训练来将时间信息（例如睡眠阶段转换规则）编码到模型中。
实现了一种两步训练算法，可以通过反向传播有效地端到端训练我们的模型，同时防止模型遭受大睡眠中出现的类别不平衡问题（即学习仅对大多数睡眠阶段进行分类）数据集。
在不改变模型架构和训练算法的情况下，模型可以从两个数据集的不同原始单通道脑电图自动学习睡眠阶段评分的特征，这两个数据集具有不同的属性（例如采样率）和评分标准（ AASM 和 R&K）。

环境配置

python3.5.4
tensorflowgpu 1.15.2

数据

Sleep-EDF

MASS

方法

模型主要代码：

class MyModel(DeepFeatureNet):def __init__(self, batch_size, input_dims, n_classes, seq_length,n_rnn_layers,return_last,is_train, reuse_params,use_dropout_feature, use_dropout_sequence,name="deepsleepnet"):super(self.__class__, self).__init__(batch_size=batch_size, input_dims=input_dims, n_classes=n_classes, is_train=is_train, reuse_params=reuse_params, use_dropout=use_dropout_feature, name=name)self.seq_length = seq_lengthself.n_rnn_layers = n_rnn_layersself.return_last = return_lastself.use_dropout_sequence = use_dropout_sequencedef _build_placeholder(self):# Inputname = "x_train" if self.is_train else "x_valid"self.input_var = tf.compat.v1.placeholder(tf.float32, shape=[self.batch_size*self.seq_length, self.input_dims, 1, 1],name=name + "_inputs")# Targetself.target_var = tf.compat.v1.placeholder(tf.int32, shape=[self.batch_size*self.seq_length, ],name=name + "_targets")def build_model(self, input_var):# Create a network with superclass methodnetwork = super(self.__class__, self).build_model(input_var=self.input_var)# Residual (or shortcut) connectionoutput_conns = []# Fully-connected to select some part of the output to add with the output from bi-directional LSTMname = "l{}_fc".format(self.layer_idx)with tf.compat.v1.variable_scope(name) as scope:output_tmp = fc(name="fc", input_var=network, n_hiddens=1024, bias=None, wd=0)output_tmp = batch_norm_new(name="bn", input_var=output_tmp, is_train=self.is_train)# output_tmp = leaky_relu(name="leaky_relu", input_var=output_tmp)output_tmp = tf.nn.relu(output_tmp, name="relu")self.activations.append((name, output_tmp))self.layer_idx += 1output_conns.append(output_tmp)####################################################################### Reshape the input from (batch_size * seq_length, input_dim) to# (batch_size, seq_length, input_dim)name = "l{}_reshape_seq".format(self.layer_idx)input_dim = network.get_shape()[-1].valueseq_input = tf.reshape(network,shape=[-1, self.seq_length, input_dim],name=name)assert self.batch_size == seq_input.get_shape()[0].valueself.activations.append((name, seq_input))self.layer_idx += 1# Bidirectional LSTM networkname = "l{}_bi_lstm".format(self.layer_idx)hidden_size = 512   # will output 1024 (512 forward, 512 backward)with tf.compat.v1.variable_scope(name) as scope:def lstm_cell():cell = tf.compat.v1.nn.rnn_cell.LSTMCell(hidden_size,                               use_peepholes=True,state_is_tuple=True,reuse=tf.compat.v1.get_variable_scope().reuse) if self.use_dropout_sequence:keep_prob = 0.5 if self.is_train else 1.0cell = tf.compat.v1.nn.rnn_cell.DropoutWrapper(cell,output_keep_prob=keep_prob)return cellfw_cell = tf.compat.v1.nn.rnn_cell.MultiRNNCell([lstm_cell() for _ in range(self.n_rnn_layers)], state_is_tuple = True)bw_cell = tf.compat.v1.nn.rnn_cell.MultiRNNCell([lstm_cell() for _ in range(self.n_rnn_layers)], state_is_tuple = True)# Initial state of RNNself.fw_initial_state = fw_cell.zero_state(self.batch_size, tf.float32)self.bw_initial_state = bw_cell.zero_state(self.batch_size, tf.float32)# Feedforward to MultiRNNCelllist_rnn_inputs = tf.unstack(seq_input, axis=1)#outputs, fw_state, bw_state = tf.nn.bidirectional_rnn(outputs, fw_state, bw_state = tf.compat.v1.nn.static_bidirectional_rnn(cell_fw=fw_cell,cell_bw=bw_cell,inputs=list_rnn_inputs,initial_state_fw=self.fw_initial_state,initial_state_bw=self.bw_initial_state)if self.return_last:network = outputs[-1]else:network = tf.reshape(tf.concat(axis=1, values=outputs), [-1, hidden_size*2],name=name)self.activations.append((name, network))self.layer_idx +=1self.fw_final_state = fw_stateself.bw_final_state = bw_state# Append outputoutput_conns.append(network)####################################################################### Addname = "l{}_add".format(self.layer_idx)network = tf.add_n(output_conns, name=name)self.activations.append((name, network))self.layer_idx += 1# Dropoutif self.use_dropout_sequence:name = "l{}_dropout".format(self.layer_idx)if self.is_train:network = tf.nn.dropout(network, keep_prob=0.5, name=name)else:network = tf.nn.dropout(network, keep_prob=1.0, name=name)self.activations.append((name, network))self.layer_idx += 1return networkdef init_ops(self):self._build_placeholder()# Get loss and prediction operationswith tf.compat.v1.variable_scope(self.name) as scope:# Reuse variables for validationif self.reuse_params:scope.reuse_variables()# Build modelnetwork = self.build_model(input_var=self.input_var)# Softmax linearname = "l{}_softmax_linear".format(self.layer_idx)network = fc(name=name, input_var=network, n_hiddens=self.n_classes, bias=0.0, wd=0)self.activations.append((name, network))self.layer_idx += 1# Outputs of softmax linear are logitsself.logits = network######### Compute loss ########## Weighted cross-entropy loss for a sequence of logits (per example)loss = tf.contrib.legacy_seq2seq.sequence_loss_by_example([self.logits],[self.target_var],[tf.ones([self.batch_size * self.seq_length])],name="sequence_loss_by_example")loss = tf.reduce_sum(loss) / self.batch_size# Regularization lossregular_loss = tf.add_n(tf.compat.v1.get_collection("losses", scope=scope.name + "\/"),name="regular_loss")# print " "# print "Params to compute regularization loss:"# for p in tf.compat.v1.get_collection("losses", scope=scope.name + "\/"):#     print p.name# print " "# Total lossself.loss_op = tf.add(loss, regular_loss)# Predictionsself.pred_op = tf.argmax(self.logits, 1)