def bielugru(word_input_size, word_embedding_size, sequence_embedding_size,
n_tags, word_dropout, rnn_dropout_W, rnn_dropout_U, l2,
word_embedding_weights, **kwargs):
# define network inputs: words only
text_input = Input(shape=(None, ), dtype='int32', name='text_input')
# map word indices to vector representation
word_embeddings = Embedding(input_dim=word_input_size,
output_dim=word_embedding_size,
weights=word_embedding_weights,
name="word_embeddings")(text_input)
# drop small portion of input vectors
word_embeddings = Dropout(word_dropout)(word_embeddings)
sequence_embedding = word_embeddings
# apply text level BIGRU
bidirectional_tag_sequence_output = Bidirectional(
ELUGRU(sequence_embedding_size / 2,
return_sequences=True,
dropout=rnn_dropout_W,
recurrent_dropout=rnn_dropout_U),
merge_mode="concat")(sequence_embedding)
# project hidden states to IOB tags
tag_sequence_output = TimeDistributed(
Dense(n_tags, activation='softmax', kernel_regularizer=L1L2(l2=l2)),
name="aspect_output")(bidirectional_tag_sequence_output)
# construct Model object and compile
model = Model(inputs=[text_input], outputs=[tag_sequence_output])
adam = Adam()
model.compile(optimizer=adam,
loss={'aspect_output': "categorical_crossentropy"},
sample_weight_mode="temporal")
model._make_train_function()
model._make_predict_function()
return model,
def char_bielugru(word_input_size, word_embedding_size, char_input_size,
char_embedding_size, sequence_embedding_size, n_tags,
word_dropout, rnn_dropout_W, rnn_dropout_U, dropout, l2,
word_embedding_weights, **kwargs):
# define network inputs: words and character indices
text_input = Input(shape=(None, ), dtype='int32', name='text_input')
char_input = Input(shape=(
None,
None,
), dtype='int32', name='char_input')
# map word indices to vector representations
word_embeddings = Embedding(input_dim=word_input_size,
output_dim=word_embedding_size,
weights=word_embedding_weights,
name="word_embeddings")(text_input)
word_embeddings = Dropout(word_dropout)(word_embeddings)
# map each character for each word to its vector representation
char_embedding_layer = Embedding(input_dim=char_input_size,
output_dim=char_embedding_size,
name="char_embeddings")
char_embeddings = BetterTimeDistributed(char_embedding_layer)(char_input)
char_embeddings = Dropout(word_dropout)(char_embeddings)
##################
# apply char-level BiGRU to every word
char_word_model = Bidirectional(ELUGRU(char_embedding_size,
return_sequences=False),
merge_mode="concat")
char_word_embeddings = BetterTimeDistributed(char_word_model)(
char_embeddings)
char_word_embeddings = Dropout(dropout)(char_word_embeddings)
# project final states to fixed size representation
char_word_embeddings = BetterTimeDistributed(
Dense(char_embedding_size,
kernel_regularizer=L1L2(l2=l2)))(char_word_embeddings)
##################
# combine word and character emebeddings
sequence_embedding = concatenate([word_embeddings, char_word_embeddings])
# apply text level BIGRU
bidirectional_tag_sequence_output = Bidirectional(
ELUGRU(sequence_embedding_size / 2,
return_sequences=True,
dropout=rnn_dropout_W,
recurrent_dropout=rnn_dropout_U),
merge_mode="concat")(sequence_embedding)
# project hidden states to IOB tags
tag_sequence_output = TimeDistributed(
Dense(n_tags, activation='softmax', kernel_regularizer=L1L2(l2=l2)),
name="aspect_output")(bidirectional_tag_sequence_output)
# construct Model object and compile
model = Model(inputs=[text_input, char_input],
outputs=[tag_sequence_output])
adam = Adam()
model.compile(optimizer=adam,
loss={'aspect_output': "categorical_crossentropy"},
sample_weight_mode="temporal")
model._make_train_function()
model._make_predict_function()
# construct Model object to obtain the character-level verctor representation for a single word
char_word_input = Input(shape=(None, ),
dtype='int32',
name='char_word_input')
char_word_embedding = char_embedding_layer(char_word_input)
char_word_embedding = char_word_model(char_word_embedding)
char_word_model = Model(input=[char_word_input],
output=[char_word_embedding])
char_word_model._make_predict_function()
return model, char_word_model