def __init__(self, config, pretrained_embedding):
self._input = tf.placeholder(dtype=tf.int32,shape=[None,None],name='input')
self._target = tf.placeholder(dtype=tf.int32,shape=[None],name='target')
self.batch_size = config['batch_size']
self.num_steps = config['num_steps']
self.embed_size = config['embed_size']
self.size = config['hidden_size']
self._lr = config['lr']
self.num_classes = config['num_classes']
self.keep_prob = tf.Variable(config['keep_prob'],trainable=False)
self.combine_mode = config['combine_mode']
self.weight_decay = config['weight_decay']
#
# outputs = LSTMEncoderWithEmbedding(self._input,self.embed_size,self.size,\
# config['vocab_size'],self.num_steps,\
# self.keep_prob,embedding=pretrained_embedding,\
# num_layers=config['num_layers'],\
# variational_dropout=True,\
# combine_mode='last').get_output()
embed = Embedding(config['vocab_size']+1, self.embed_size)(self._input)
outputs = tf.nn.dropout(embed,keep_prob=self.keep_prob)
# outputs = Bidirectional(CuDNNLSTM(self.size,return_sequences=True))(outputs)
# outputs = tf.nn.dropout(outputs,keep_prob=self.keep_prob)
outputs = Bidirectional(CuDNNLSTM(self.size,return_sequences=True))(outputs)
self.size = int(outputs.get_shape().as_list()[-1])
if self.combine_mode =='weight':
outputs = tf.reshape(outputs,[-1,self.size])
weights = Dense(1,activation='tanh')(outputs)
outputs = tf.multiply(outputs,weights)
outputs = tf.reshape(outputs,[-1,self.num_steps,self.size])
outputs = tf.reduce_sum(outputs,axis=1)
elif self.combine_mode =='last':
outputs = outputs[:,-1,:]
elif self.combine_mode =='all':
weights = Dense(1,activation='tanh')(outputs)
outputs_weighted = tf.multiply(outputs,weights)
outputs_weighted = tf.reshape(outputs_weighted,[-1,self.num_steps,2*self.size])
outputs_weighted = tf.reduce_sum(outputs_weighted,axis=1)
outputs_last = outputs[:,-1,:]
outputs_mean = tf.reduce_mean(outputs,axis=1)
outputs_max = tf.reduce_max(outputs,axis=1)
outputs_min = tf.reduce_min(outputs,axis=1)
outputs = tf.concat([outputs_last,outputs_mean,outputs_max,outputs_min,outputs_weighted],axis=-1)
# outputs = tf.nn.dropout(outputs,keep_prob=self.keep_prob)
embed_avg = tf.reduce_mean(embed,axis=1)
# embed_max = tf.reduce_max(embed,axis=1)
# embed_min = tf.reduce_min(embed,axis=1)
# outputs = tf.concat([outputs,embed_avg,embed_min,embed_max],axis=-1)
outputs = tf.concat([outputs,embed_avg] ,axis=-1)
# outputs = tf.contrib.layers.fully_connected(outputs,self.size)
# outputs = tf.nn.dropout(outputs,keep_prob=self.keep_prob)
# softmax_w = tf.get_variable("softmax_w", [self.size, self.num_classes], dtype=tf.float32)
# softmax_b = tf.get_variable("softmax_b", [self.num_classes], dtype=tf.float32)
# logits = tf.matmul(outputs, softmax_w) + softmax_b
logits = Dense(self.num_classes,activation=None)(outputs)
# update the cost variables
loss = tf.nn.sparse_softmax_cross_entropy_with_logits(labels=self._target,logits=logits)
self.l2_loss = sum(tf.nn.l2_loss(tf_var)
for tf_var in tf.trainable_variables()
)
self._cost = cost = tf.reduce_mean(loss) + self.weight_decay*self.l2_loss
self._lr = tf.Variable(self._lr, trainable=False)
tvars = tf.trainable_variables()
grads, _ = tf.clip_by_global_norm(tf.gradients(cost, tvars),
config['max_grad_norm'])
optimizer = tf.train.AdamOptimizer(self._lr)
# optimizer = tf.train.GradientDescentOptimizer(self._lr)
self._train_op = optimizer.apply_gradients(zip(grads, tvars))
self._new_lr = tf.placeholder(tf.float32, shape=[], name="new_learning_rate")
self._lr_update = tf.assign(self._lr, self._new_lr)
self.predicted_class = tf.cast(tf.argmax(tf.nn.softmax(logits),axis=-1),tf.int32)
def cnn_bilstm_model(pooling_size=3,
nb_filters=32,
filters_length=10,
lstm_units=32,
attention_size=50):
'''build model'''
input = Input(shape=(None, ), dtype='int8')
embedding_layer = Embedding(len(encoding_vectors),
len(encoding_vectors[0]),
weights=[encoding_vectors],
input_length=None,
trainable=False)
embedding_output = embedding_layer(input)
with tf.name_scope('first_cnn'):
# first cnn layer
cnn_output = Dropout(0.2)(
MaxPooling1D(pool_length=pooling_size, stride=pooling_size)(
Convolution1D(nb_filters,
filters_length,
border_mode='same',
activation='relu',
input_shape=(None, 24))(embedding_output))
# output shape is in (batch_size, steps, filters), normalizing over the feature axis which is -1
)
with tf.name_scope('Second_cnn'):
# stack another cnn layer on top
cnn_output = Dropout(0.2)(MaxPooling1D(
pool_length=pooling_size,
stride=pooling_size)(Convolution1D(nb_filters,
filters_length,
border_mode='same',
activation='relu')(cnn_output)))
with tf.name_scope('Third_cnn'):
# stack another cnn layer on top
cnn_output = Dropout(0.2)(MaxPooling1D(
pool_length=pooling_size,
stride=pooling_size)(Convolution1D(nb_filters,
filters_length,
border_mode='same',
activation='relu')(cnn_output)))
with tf.name_scope('Fourth_cnn'):
# stack another cnn layer on top
cnn_output = Dropout(0.2)(MaxPooling1D(
pool_length=pooling_size,
stride=pooling_size)(Convolution1D(nb_filters,
filters_length,
border_mode='same',
activation='relu')(cnn_output)))
with tf.name_scope('bilstm_layer'):
lstm_output = Bidirectional(
LSTM(lstm_units,
dropout=0.1,
return_sequences=True,
input_shape=(None, nb_filters)))(cnn_output)
# output shape: (batch_size, time steps, hidden size=2*nb_filters)
hidden_size = lstm_output.get_shape()[2].value
print('hidden size:', hidden_size)
with tf.name_scope('attention_module'):
# [batch_size, time_steps, attention_size]
context_weights = Dense(attention_size,
activation='tanh',
kernel_initializer=random_normal(),
bias_initializer=random_normal())(lstm_output)
# [batch_size, time_steps]
scores = Lambda(lambda x: K.batch_flatten(x))(
Dense(1, kernel_initializer=random_normal(),
use_bias=False)(context_weights))
# softmax probability distribution, [batch_size, sequence_length]
attention_weights = Lambda(lambda x: K.expand_dims(x, axis=-1))(
Activation("softmax")(scores))
# Multiply() behaves exactly as tf.multiply() which supports shape broadcasting, so its output_shape is [batch_size, time_steps, hidden_size]
# Lambda(lambda x: K.sum(x, axis=1, keepdims=False)) is equivalent to tf.reduce_sum(axis=1)
# [batch_size, hidden]
output = Lambda(lambda x: K.sum(x, axis=1, keepdims=False))(
Multiply()([lstm_output, attention_weights]))
preds = Dense(nb_classes, activation='softmax')(output)
model = Model(inputs=[input], outputs=preds)
from keras import optimizers
optim = optimizers.adam(lr=0.0001)
# optim = optimizers.sgd(lr=0.001)
model.compile(loss='kld', optimizer=optim, metrics=['acc'])
return model
maxLen = len(max(x_train, key=len))
units = 128
_input = Input(shape=(maxLen, ), dtype='float32')
# get the embedding layer
embedding_layer = Embedding(input_dim=len(word_index) + 1,
output_dim=EMBEDDING_DIM,
weights=[embedding_matrix],
input_length=maxLen,
trainable=False)
embedded = embedding_layer(_input)
activations = Bidirectional(LSTM(int(units / 2), return_sequences=True),
name='bidirectional_lstm')(embedded)
print(activations.get_shape()) # (None, 229, 256)
# activations = LSTM(units, return_sequences = True)(embedded)
# compute importance for each step
attention = Dense(1, activation='tanh')(activations)
# print(attention.get_shape()) # (None, 229, 1)
attention = Flatten()(attention)
# print(attention.get_shape()) # (None, 229)
attention = Activation('softmax')(attention)
# print(attention.get_shape()) # (None, 229)
attention = RepeatVector(units)(attention)
# print(attention.get_shape()) # (None, 128, 229)
attention = Permute([2, 1])(attention)
# print(attention.get_shape()) # (None, 229, 128)
# apply the attention
