def generate(model, input, enc_fwd_lstm, enc_bwd_lstm, dec_lstm):
def sample(probs):
rnd = random.random()
for i, p in enumerate(probs):
rnd -= p
if rnd <= 0: break
return i
embedded = embedd_sentence(model, input)
encoded = encode_sentence(model, enc_fwd_lstm, enc_bwd_lstm, embedded)
w = pc.parameter(model["decoder_w"])
b = pc.parameter(model["decoder_b"])
s = dec_lstm.initial_state().add_input(pc.vecInput(STATE_SIZE * 2))
out = ''
count_EOS = 0
for i in range(len(input)*2):
if count_EOS == 2: break
vector = attend(model, encoded, s)
s = s.add_input(vector)
out_vector = w * s.output() + b
probs = pc.softmax(out_vector)
probs = probs.vec_value()
next_char = sample(probs)
if int2char[next_char] == EOS:
count_EOS += 1
continue
out += int2char[next_char]
return out
def predict(sent, model, builders):
"""
predict tags and demographic labels
:param sent:
:param model:
:param builders:
:return: tag and label predictions
"""
if MLP:
H = pycnn.parameter(pH)
O = pycnn.parameter(pO)
else:
O = pycnn.parameter(pO)
tags = []
for forward_state, backward_state in build_tagging_graph(words, model, builders):
if MLP:
r_t = O * (pycnn.tanh(H * pycnn.concatenate([forward_state, backward_state])))
else:
r_t = O * pycnn.concatenate([forward_state, backward_state])
out = pycnn.softmax(r_t)
chosen = np.argmax(out.npvalue())
tags.append(vocab_tags.i2w[chosen])
return tags
def generate(model, input, enc_fwd_lstm, enc_bwd_lstm, dec_lstm):
def sample(probs):
rnd = random.random()
for i, p in enumerate(probs):
rnd -= p
if rnd <= 0: break
return i
embedded = embedd_sentence(model, input)
encoded = encode_sentence(model, enc_fwd_lstm, enc_bwd_lstm, embedded)
w = pc.parameter(model["decoder_w"])
b = pc.parameter(model["decoder_b"])
s = dec_lstm.initial_state().add_input(pc.vecInput(STATE_SIZE * 2))
out = ''
count_EOS = 0
for i in range(len(input) * 2):
if count_EOS == 2: break
vector = attend(model, encoded, s)
s = s.add_input(vector)
out_vector = w * s.output() + b
probs = pc.softmax(out_vector)
probs = probs.vec_value()
next_char = sample(probs)
if int2char[next_char] == EOS:
count_EOS += 1
continue
out += int2char[next_char]
return out
def fit(words, tags, labels, model, builders):
"""
compute joint error of the
:param words: list of indices
:param tags: list of indices
:param labels: index
:param model: current model to access parameters
:param builders: builder to create state combinations
:return: joint error
"""
# retrieve model parameters
if MLP:
H = pycnn.parameter(pH)
O = pycnn.parameter(pO)
else:
O = pycnn.parameter(pO)
errs = []
for (forward_state, backward_state), tag in zip(build_tagging_graph(words, model, builders), tags):
f_b = pycnn.concatenate([forward_state, backward_state])
if MLP:
# TODO: add bias terms
r_t = O * (pycnn.tanh(H * f_b))
else:
r_t = O * f_b
err = pycnn.pickneglogsoftmax(r_t, tag)
errs.append(err)
return pycnn.esum(errs)
def attend(model, input_vectors, state):
w1 = pc.parameter(model['attention_w1'])
w2 = pc.parameter(model['attention_w2'])
v = pc.parameter(model['attention_v'])
attention_weights = []
w2dt = w2*pc.concatenate(list(state.s()))
for input_vector in input_vectors:
attention_weight = v*pc.tanh(w1*input_vector + w2dt)
attention_weights.append(attention_weight)
attention_weights = pc.softmax(pc.concatenate(attention_weights))
output_vectors = pc.esum([vector*attention_weight for vector, attention_weight in zip(input_vectors, attention_weights)])
return output_vectors
def attend(model, input_vectors, state):
w1 = pc.parameter(model['attention_w1'])
w2 = pc.parameter(model['attention_w2'])
v = pc.parameter(model['attention_v'])
attention_weights = []
w2dt = w2*pc.concatenate(list(state.s()))
for input_vector in input_vectors:
attention_weight = v*pc.tanh(w1*input_vector + w2dt)
attention_weights.append(attention_weight)
attention_weights = pc.softmax(pc.concatenate(attention_weights))
output_vectors = pc.esum([vector*attention_weight for vector, attention_weight in zip(input_vectors, attention_weights)])
return output_vectors
def _build_word_expression_list(self, sentence, is_train=False):
renew_cg()
sentence_word_vectors = []
for word in sentence:
sentence_word_vectors.append(self._get_word_vector(word, use_dropout=is_train))
lstm_forward = self.word_builders[0].initial_state()
lstm_backward = self.word_builders[1].initial_state()
embeddings_forward = []
embeddings_backward = []
for word_vector, reverse_word_vector in zip(sentence_word_vectors, reversed(sentence_word_vectors)):
lstm_forward = lstm_forward.add_input(word_vector)
lstm_backward = lstm_backward.add_input(reverse_word_vector)
embeddings_forward.append(lstm_forward.output())
embeddings_backward.append(lstm_backward.output())
O = parameter(self.param_out)
sentence_word_expressions = []
for word_f_embedding, word_b_embedding in zip(embeddings_forward, reversed(embeddings_backward)):
word_concat_embedding = concatenate([word_f_embedding, word_b_embedding])
word_expression = O * word_concat_embedding
sentence_word_expressions.append(word_expression)
return sentence_word_expressions
def calc_sentence_error_semi_viterbi(self, sentence):
word_expression_list = self._build_word_expression_list(sentence, is_train=True)
transition_matrix = parameter(self.param_transition)
gold_expr = self._get_gold_expression(sentence, word_expression_list, transition_matrix)
output_expr, _ = self.decode_sentence_tags_by_viterbi(word_expression_list, transition_matrix)
return exp(output_expr - gold_expr)
def calc_sentence_error_viterbi(self, sentence):
word_expression_list = self._build_word_expression_list(sentence, is_train=True)
transition_matrix = parameter(self.param_transition)
gold_expr = self._get_gold_expression(sentence, word_expression_list, transition_matrix)
all_sequence_expr = self._get_all_sequence_expr(word_expression_list, transition_matrix)
return all_sequence_expr - gold_expr
def do_cpu(): C.renew_cg() W = C.parameter(cpW) W = W*W*W*W*W*W*W z = C.squared_distance(W,W) z.value() z.backward()
def _build_word_expression_list(self, sentence, is_train=False):
renew_cg()
sentence_word_vectors = []
for word in sentence:
sentence_word_vectors.append(
self._get_word_vector(word, use_dropout=is_train))
lstm_forward = self.word_builders[0].initial_state()
lstm_backward = self.word_builders[1].initial_state()
embeddings_forward = []
embeddings_backward = []
for word_vector, reverse_word_vector in zip(
sentence_word_vectors, reversed(sentence_word_vectors)):
lstm_forward = lstm_forward.add_input(word_vector)
lstm_backward = lstm_backward.add_input(reverse_word_vector)
embeddings_forward.append(lstm_forward.output())
embeddings_backward.append(lstm_backward.output())
O = parameter(self.param_out)
sentence_word_expressions = []
for word_f_embedding, word_b_embedding in zip(
embeddings_forward, reversed(embeddings_backward)):
word_concat_embedding = concatenate(
[word_f_embedding, word_b_embedding])
word_expression = O * word_concat_embedding
sentence_word_expressions.append(word_expression)
return sentence_word_expressions
def predict(word_indices, model, builder, target):
"""
predict demographic label
:param word_indices:
:param model:
:param builder:
:return: tag and label predictions
"""
forward_states = build_tagging_graph(word_indices, model, builder)
final_state = forward_states[-1]
H = pycnn.parameter(pH)
bias_H = pycnn.parameter(biasH)
H2 = pycnn.parameter(pH2)
bias_H2 = pycnn.parameter(biasH2)
if target in ['age', 'both', 'joint']:
O = pycnn.parameter(pOutAge)
bias_O = pycnn.parameter(biasOutAge)
elif target == 'gender':
O = pycnn.parameter(pOutGender)
bias_O = pycnn.parameter(biasOutGender)
if target == 'both':
O2 = pycnn.parameter(pOutGender)
bias_O2 = pycnn.parameter(biasOutGender)
if target == 'both':
# hidden = bias_H2 + pycnn.tanh(H2 * (bias_H + pycnn.tanh(H * final_state)))
hidden = bias_H + pycnn.tanh(H * final_state)
r_age = bias_O + (O * hidden)
r_gender = bias_O2 + (O2 * hidden)
out_age = pycnn.softmax(r_age)
out_gender = pycnn.softmax(r_gender)
return [np.argmax(out_age.npvalue()), np.argmax(out_gender.npvalue())]
else:
# r_t = bias_O + (O * (bias_H2 + pycnn.tanh(H2 * (bias_H + pycnn.tanh(H * final_state)))))
r_t = bias_O + (O * (bias_H + (H * final_state)))
out = pycnn.softmax(r_t)
chosen = np.argmax(out.npvalue())
return chosen
def tag_sentence_viterbi(self, sentence):
word_expression_list = self._build_word_expression_list(sentence, is_train=False)
transition_matrix = parameter(self.param_transition)
best_score_expression, sentence_tags = self.decode_sentence_tags_by_viterbi(word_expression_list,
transition_matrix)
for word, word_tag in zip(sentence, sentence_tags):
word.tag = word_tag
def tag_sentence_viterbi(self, sentence):
word_expression_list = self._build_word_expression_list(sentence,
is_train=False)
transition_matrix = parameter(self.param_transition)
best_score_expression, sentence_tags = self.decode_sentence_tags_by_viterbi(
word_expression_list, transition_matrix)
for word, word_tag in zip(sentence, sentence_tags):
word.tag = word_tag
def decode(model, dec_lstm, vectors, output):
output = [EOS] + list(output) + [EOS]
output = [char2int[c] for c in output]
w = pc.parameter(model["decoder_w"])
b = pc.parameter(model["decoder_b"])
s = dec_lstm.initial_state().add_input(pc.vecInput(STATE_SIZE * 2))
loss = []
for char in output:
vector = attend(model, vectors, s)
s = s.add_input(vector)
out_vector = w * s.output() + b
probs = pc.softmax(out_vector)
loss.append(-pc.log(pc.pick(probs, char)))
loss = pc.esum(loss)
return loss
def decode(model, dec_lstm, vectors, output):
output = [EOS] + list(output) + [EOS]
output = [char2int[c] for c in output]
w = pc.parameter(model["decoder_w"])
b = pc.parameter(model["decoder_b"])
s = dec_lstm.initial_state().add_input(pc.vecInput(STATE_SIZE*2))
loss = []
for char in output:
vector = attend(model, vectors, s)
s = s.add_input(vector)
out_vector = w * s.output() + b
probs = pc.softmax(out_vector)
loss.append(-pc.log(pc.pick(probs, char)))
loss = pc.esum(loss)
return loss
def calc_sentence_error_viterbi(self, sentence):
word_expression_list = self._build_word_expression_list(sentence,
is_train=True)
transition_matrix = parameter(self.param_transition)
gold_expr = self._get_gold_expression(sentence, word_expression_list,
transition_matrix)
all_sequence_expr = self._get_all_sequence_expr(
word_expression_list, transition_matrix)
return all_sequence_expr - gold_expr
def calc_sentence_error_semi_viterbi(self, sentence):
word_expression_list = self._build_word_expression_list(sentence,
is_train=True)
transition_matrix = parameter(self.param_transition)
gold_expr = self._get_gold_expression(sentence, word_expression_list,
transition_matrix)
output_expr, _ = self.decode_sentence_tags_by_viterbi(
word_expression_list, transition_matrix)
return exp(output_expr - gold_expr)
def prep_params(self):
self.W1_struct = pycnn.parameter(self.model['struct-hidden-W'])
self.b1_struct = pycnn.parameter(self.model['struct-hidden-b'])
self.W2_struct = pycnn.parameter(self.model['struct-out-W'])
self.b2_struct = pycnn.parameter(self.model['struct-out-b'])
self.W1_label = pycnn.parameter(self.model['label-hidden-W'])
self.b1_label = pycnn.parameter(self.model['label-hidden-b'])
self.W2_label = pycnn.parameter(self.model['label-out-W'])
self.b2_label = pycnn.parameter(self.model['label-out-b'])
def attend(model, vectors, state):
w = pc.parameter(model['attention_w'])
attention_weights = []
for vector in vectors:
#concatenate each encoded vector with the current decoder state
attention_input = pc.concatenate([vector, pc.concatenate(list(state.s()))])
#get the attention wieght for the decoded vector
attention_weights.append(w * attention_input)
#normalize the weights
attention_weights = pc.softmax(pc.concatenate(attention_weights))
#apply the weights
vectors = pc.esum([vector*attention_weight for vector, attention_weight in zip(vectors, attention_weights)])
return vectors
def _build_sentence_expressions(self, sentence):
lstm_forward = self.word_builders[0].initial_state()
lstm_backward = self.word_builders[1].initial_state()
embeddings_forward = []
embeddings_backward = []
for word, reverse_word in zip(sentence, reversed(sentence)):
lstm_forward = lstm_forward.add_input(word.vector)
lstm_backward = lstm_backward.add_input(reverse_word.vector)
embeddings_forward.append(lstm_forward.output())
embeddings_backward.append(lstm_backward.output())
H = parameter(self.param_hidden)
O = parameter(self.param_out)
sentence_expressions = []
for word_f_embedding, word_b_embedding in zip(embeddings_forward, reversed(embeddings_backward)):
word_concat_embedding = concatenate([word_f_embedding, word_b_embedding])
word_expression = O * self.activation(H * word_concat_embedding)
sentence_expressions.append(word_expression)
return sentence_expressions
def predict_output_sequence(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, alphabet_index,
inverse_alphabet_index, feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
W_c = pc.parameter(model["W_c"])
W__a = pc.parameter(model["W__a"])
U__a = pc.parameter(model["U__a"])
v__a = pc.parameter(model["v__a"])
# encode the lemma
blstm_outputs = encode_chars(alphabet_index, char_lookup, encoder_frnn, encoder_rrnn, lemma)
# convert features to matching embeddings, if UNK handle properly
feats_input = encode_feats(feat_index, feat_lookup, feats, feature_types)
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
i = 0
predicted_sequence = []
# run the decoder through the sequence and predict characters
while i < MAX_PREDICTION_LEN:
# get current h of the decoder
s = s.add_input(pc.concatenate([prev_output_vec, feats_input]))
decoder_rnn_output = s.output()
# perform attention step
attention_output_vector, alphas, W = task1_attention_implementation.attend(blstm_outputs, decoder_rnn_output,
W_c, v__a, W__a, U__a)
# compute output probabilities
# print 'computing readout layer...'
readout = R * attention_output_vector + bias
# find best candidate output
probs = pc.softmax(readout)
next_char_index = common.argmax(probs.vec_value())
predicted_sequence.append(inverse_alphabet_index[next_char_index])
# check if reached end of word
if predicted_sequence[-1] == END_WORD:
break
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[next_char_index]
i += 1
# remove the end word symbol
return predicted_sequence[0:-1]
def __init__(self, lstm):
self.lstm = lstm
self.outputs = []
self.c = pycnn.parameter(self.lstm.c0)
self.h = pycnn.tanh(self.c)
self.W_i = pycnn.parameter(self.lstm.W_i)
self.b_i = pycnn.parameter(self.lstm.b_i)
self.W_f = pycnn.parameter(self.lstm.W_f)
self.b_f = pycnn.parameter(self.lstm.b_f)
self.W_c = pycnn.parameter(self.lstm.W_c)
self.b_c = pycnn.parameter(self.lstm.b_c)
self.W_o = pycnn.parameter(self.lstm.W_o)
self.b_o = pycnn.parameter(self.lstm.b_o)
def _build_sentence_expressions(self, sentence):
lstm_forward = self.word_builders[0].initial_state()
lstm_backward = self.word_builders[1].initial_state()
embeddings_forward = []
embeddings_backward = []
for word, reverse_word in zip(sentence, reversed(sentence)):
lstm_forward = lstm_forward.add_input(word.vector)
lstm_backward = lstm_backward.add_input(reverse_word.vector)
embeddings_forward.append(lstm_forward.output())
embeddings_backward.append(lstm_backward.output())
H = parameter(self.param_hidden)
O = parameter(self.param_out)
sentence_expressions = []
for word_f_embedding, word_b_embedding in zip(
embeddings_forward, reversed(embeddings_backward)):
word_concat_embedding = concatenate(
[word_f_embedding, word_b_embedding])
word_expression = O * self.activation(H * word_concat_embedding)
sentence_expressions.append(word_expression)
return sentence_expressions
def compute_loss(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats,
word, alphabet_index, feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
W_c = pc.parameter(model["W_c"])
W__a = pc.parameter(model["W__a"])
U__a = pc.parameter(model["U__a"])
v__a = pc.parameter(model["v__a"])
blstm_outputs = encode_chars(alphabet_index, char_lookup, encoder_frnn,
encoder_rrnn, lemma)
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# convert features to matching embeddings, if UNK handle properly
feats_input = encode_feats(feat_index, feat_lookup, feats, feature_types)
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
loss = []
padded_word = word + END_WORD
# run the decoder through the output sequence and aggregate loss
for i, output_char in enumerate(padded_word):
# get current h of the decoder
s = s.add_input(pc.concatenate([prev_output_vec, feats_input]))
decoder_rnn_output = s.output()
attention_output_vector, alphas, W = task1_attention_implementation.attend(
blstm_outputs, decoder_rnn_output, W_c, v__a, W__a, U__a)
# compute output probabilities
# print 'computing readout layer...'
readout = R * attention_output_vector + bias
current_loss = pc.pickneglogsoftmax(readout,
alphabet_index[output_char])
# print 'computed readout layer'
loss.append(current_loss)
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[output_char]]
total_sequence_loss = pc.esum(loss)
# loss = average(loss)
return total_sequence_loss
def compute_loss(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, word, alphabet_index, feat_index,
feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
W_c = pc.parameter(model["W_c"])
W__a = pc.parameter(model["W__a"])
U__a = pc.parameter(model["U__a"])
v__a = pc.parameter(model["v__a"])
blstm_outputs = encode_chars(alphabet_index, char_lookup, encoder_frnn, encoder_rrnn, lemma)
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# convert features to matching embeddings, if UNK handle properly
feats_input = encode_feats(feat_index, feat_lookup, feats, feature_types)
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
loss = []
padded_word = word + END_WORD
# run the decoder through the output sequence and aggregate loss
for i, output_char in enumerate(padded_word):
# get current h of the decoder
s = s.add_input(pc.concatenate([prev_output_vec, feats_input]))
decoder_rnn_output = s.output()
attention_output_vector, alphas, W = task1_attention_implementation.attend(blstm_outputs, decoder_rnn_output,
W_c, v__a, W__a, U__a)
# compute output probabilities
# print 'computing readout layer...'
readout = R * attention_output_vector + bias
current_loss = pc.pickneglogsoftmax(readout, alphabet_index[output_char])
# print 'computed readout layer'
loss.append(current_loss)
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[output_char]]
total_sequence_loss = pc.esum(loss)
# loss = average(loss)
return total_sequence_loss
def fit(word_indices, label, model, builder, target):
"""
compute joint error of the
:param word_indices: list of indices
:param label: index
:param model: current model to access parameters
:param builder: builder to create state combinations
:return: joint error
"""
forward_states = build_tagging_graph(word_indices, model, builder)
# retrieve model parameters
final_state = forward_states[-1]
# final_state = pycnn.dropout(final_state, 0.1)
# print("final state", final_state, file=sys.stderr)
H = pycnn.parameter(pH)
bias_H = pycnn.parameter(biasH)
H2 = pycnn.parameter(pH2)
bias_H2 = pycnn.parameter(biasH2)
if target in ['age', 'joint']:
O = pycnn.parameter(pOutAge)
bias_O = pycnn.parameter(biasOutAge)
elif target == 'gender':
O = pycnn.parameter(pOutGender)
bias_O = pycnn.parameter(biasOutGender)
# print(pycnn.cg().PrintGraphviz())
# if target == 'both':
# hidden = bias_H + pycnn.tanh(H * final_state)
# r_age = bias_O + (O * hidden)
# r_gender = bias_O2 + (O2 * hidden)
# return pycnn.esum([pycnn.pickneglogsoftmax(r_age, label[0]), pycnn.pickneglogsoftmax(r_gender, label[1])])
# r_t = bias_O + (O * (bias_H2 + pycnn.tanh(H2 * (bias_H + pycnn.tanh(H * final_state)))))
r_t = bias_O + (O * (bias_H + (H * final_state)))
# return pycnn.pick(r_t, label)
return pycnn.pickneglogsoftmax(r_t, label)
def one_word_loss(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, word, alphabet_index, aligned_pair,
feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
padded_lemma = BEGIN_WORD + lemma + END_WORD
# convert characters to matching embeddings
lemma_char_vecs = []
for char in padded_lemma:
try:
lemma_char_vecs.append(char_lookup[alphabet_index[char]])
except KeyError:
# handle UNK
lemma_char_vecs.append(char_lookup[alphabet_index[UNK]])
# convert features to matching embeddings, if UNK handle properly
feat_vecs = []
for feat in sorted(feature_types):
# TODO: is it OK to use same UNK for all feature types? and for unseen feats as well?
# if this feature has a value, take it from the lookup. otherwise use UNK
if feat in feats:
feat_str = feat + ':' + feats[feat]
try:
feat_vecs.append(feat_lookup[feat_index[feat_str]])
except KeyError:
# handle UNK or dropout
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
else:
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
feats_input = pc.concatenate(feat_vecs)
# BiLSTM forward pass
s_0 = encoder_frnn.initial_state()
s = s_0
frnn_outputs = []
for c in lemma_char_vecs:
s = s.add_input(c)
frnn_outputs.append(s.output())
# BiLSTM backward pass
s_0 = encoder_rrnn.initial_state()
s = s_0
rrnn_outputs = []
for c in reversed(lemma_char_vecs):
s = s.add_input(c)
rrnn_outputs.append(s.output())
# BiLTSM outputs
blstm_outputs = []
lemma_char_vecs_len = len(lemma_char_vecs)
for i in xrange(lemma_char_vecs_len):
blstm_outputs.append(pc.concatenate([frnn_outputs[i], rrnn_outputs[lemma_char_vecs_len - i - 1]]))
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
prev_char_vec = char_lookup[alphabet_index[BEGIN_WORD]]
loss = []
# i is input index, j is output index
i = 0
j = 0
# go through alignments, progress j when new output is introduced, progress i when new char is seen on lemma (no ~)
# TODO: try sutskever flip trick?
# TODO: attention on the lemma chars/feats could help here?
aligned_lemma, aligned_word = aligned_pair
aligned_lemma += END_WORD
aligned_word += END_WORD
# run through the alignments
for index, (input_char, output_char) in enumerate(zip(aligned_lemma, aligned_word)):
possible_outputs = []
# feedback, i, j, blstm[i], feats
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
# if reached the end word symbol
if output_char == END_WORD:
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
# compute local loss
loss.append(-pc.log(pc.pick(probs, alphabet_index[END_WORD])))
continue
# if there is no prefix, step
if padded_lemma[i] == BEGIN_WORD and aligned_lemma[index] != ALIGN_SYMBOL:
# perform rnn step
# feedback, i, j, blstm[i], feats
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
# compute local loss
loss.append(-pc.log(pc.pick(probs, alphabet_index[STEP])))
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[STEP]]
prev_char_vec = char_lookup[alphabet_index[EPSILON]]
i += 1
# if there is new output
if aligned_word[index] != ALIGN_SYMBOL:
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
# copy i action - maybe model as a single action?
if padded_lemma[i] == aligned_word[j]:
possible_outputs.append(str(i))
possible_outputs.append(padded_lemma[i])
else:
possible_outputs.append(aligned_word[index])
# perform rnn step
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
local_loss = pc.scalarInput(0)
max_output_loss = -pc.log(pc.pick(probs, alphabet_index[possible_outputs[0]]))
max_likelihood_output = possible_outputs[0]
# sum over all correct output possibilities and pick feedback output to be the one with the highest
# probability
for output in possible_outputs:
neg_log_likelihood = -pc.log(pc.pick(probs, alphabet_index[output]))
if neg_log_likelihood < max_output_loss:
max_likelihood_output = output
max_output_loss = neg_log_likelihood
local_loss += neg_log_likelihood
loss.append(local_loss)
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[max_likelihood_output]]
prev_char_vec = char_lookup[alphabet_index[aligned_word[index]]]
j += 1
# now check if it's time to progress on input
if i < len(padded_lemma) - 1 and aligned_lemma[index + 1] != ALIGN_SYMBOL:
# perform rnn step
# feedback, i, j, blstm[i], feats
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
# compute local loss
loss.append(-pc.log(pc.pick(probs, alphabet_index[STEP])))
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[STEP]]
prev_char_vec = char_lookup[alphabet_index[EPSILON]]
i += 1
# TODO: maybe here a "special" loss function is appropriate?
# loss = esum(loss)
loss = pc.average(loss)
return loss
def predict_output_sequence(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, alphabet_index,
inverse_alphabet_index, feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
# convert characters to matching embeddings, if UNK handle properly
padded_lemma = BEGIN_WORD + lemma + END_WORD
lemma_char_vecs = []
for char in padded_lemma:
try:
lemma_char_vecs.append(char_lookup[alphabet_index[char]])
except KeyError:
# handle UNK
lemma_char_vecs.append(char_lookup[alphabet_index[UNK]])
# convert features to matching embeddings, if UNK handle properly
feat_vecs = []
for feat in sorted(feature_types):
# TODO: is it OK to use same UNK for all feature types? and for unseen feats as well?
# if this feature has a value, take it from the lookup. otherwise use UNK
if feat in feats:
feat_str = feat + ':' + feats[feat]
try:
feat_vecs.append(feat_lookup[feat_index[feat_str]])
except KeyError:
# handle UNK or dropout
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
else:
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
feats_input = pc.concatenate(feat_vecs)
# BiLSTM forward pass
s_0 = encoder_frnn.initial_state()
s = s_0
frnn_outputs = []
for c in lemma_char_vecs:
s = s.add_input(c)
frnn_outputs.append(s.output())
# BiLSTM backward pass
s_0 = encoder_rrnn.initial_state()
s = s_0
rrnn_outputs = []
for c in reversed(lemma_char_vecs):
s = s.add_input(c)
rrnn_outputs.append(s.output())
# BiLTSM outputs
blstm_outputs = []
lemma_char_vecs_len = len(lemma_char_vecs)
for i in xrange(lemma_char_vecs_len):
blstm_outputs.append(pc.concatenate([frnn_outputs[i], rrnn_outputs[lemma_char_vecs_len - i - 1]]))
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
prev_char_vec = char_lookup[alphabet_index[BEGIN_WORD]]
# i is input index, j is output index
i = j = 0
num_outputs = 0
predicted_output_sequence = []
# run the decoder through the sequence and predict characters, twice max prediction as step outputs are added
while num_outputs < MAX_PREDICTION_LEN * 3:
# prepare input vector and perform LSTM step
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
s = s.add_input(decoder_input)
# compute softmax probs vector and predict with argmax
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
probs = probs.vec_value()
predicted_output_index = common.argmax(probs)
predicted_output = inverse_alphabet_index[predicted_output_index]
predicted_output_sequence.append(predicted_output)
# check if step or char output to promote i or j.
if predicted_output == STEP:
prev_char_vec = char_lookup[alphabet_index[EPSILON]]
if i < len(padded_lemma) - 1:
i += 1
else:
if predicted_output.isdigit():
# handle copy
# try:
# prev_char_vec = char_lookup[alphabet_index[padded_lemma[i]]]
# except KeyError:
# prev_char_vec = char_lookup[alphabet_index[UNK]]
try:
# this way END_WORD cannot be copied (as it is in the training stage)
if i < len(lemma) + 1:
prev_char_vec = char_lookup[alphabet_index[padded_lemma[i]]]
else:
# if trying to copy from a non-existent index, pad with last lemma character
prev_char_vec = char_lookup[alphabet_index[lemma[-1]]]
except KeyError:
prev_char_vec = char_lookup[alphabet_index[UNK]]
else:
# handle char
prev_char_vec = char_lookup[predicted_output_index]
j += 1
num_outputs += 1
# check if reached end of word
if predicted_output_sequence[-1] == END_WORD:
break
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[predicted_output_index]
# remove the end word symbol
return predicted_output_sequence[0:-1]
def one_word_loss(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, word, alphabet_index, aligned_pair,
feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
padded_lemma = BEGIN_WORD + lemma + END_WORD
# convert characters to matching embeddings
lemma_char_vecs = []
for char in padded_lemma:
try:
lemma_char_vecs.append(char_lookup[alphabet_index[char]])
except KeyError:
# handle UNK
lemma_char_vecs.append(char_lookup[alphabet_index[UNK]])
# convert features to matching embeddings, if UNK handle properly
feat_vecs = []
for feat in sorted(feature_types):
# TODO: is it OK to use same UNK for all feature types? and for unseen feats as well?
# if this feature has a value, take it from the lookup. otherwise use UNK
if feat in feats:
feat_str = feat + ':' + feats[feat]
try:
feat_vecs.append(feat_lookup[feat_index[feat_str]])
except KeyError:
# handle UNK or dropout
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
else:
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
feats_input = pc.concatenate(feat_vecs)
# BiLSTM forward pass
s_0 = encoder_frnn.initial_state()
s = s_0
frnn_outputs = []
for c in lemma_char_vecs:
s = s.add_input(c)
frnn_outputs.append(s.output())
# BiLSTM backward pass
s_0 = encoder_rrnn.initial_state()
s = s_0
rrnn_outputs = []
for c in reversed(lemma_char_vecs):
s = s.add_input(c)
rrnn_outputs.append(s.output())
# BiLTSM outputs
blstm_outputs = []
lemma_char_vecs_len = len(lemma_char_vecs)
for i in xrange(lemma_char_vecs_len):
blstm_outputs.append(pc.concatenate([frnn_outputs[i], rrnn_outputs[lemma_char_vecs_len - i - 1]]))
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
prev_char_vec = char_lookup[alphabet_index[BEGIN_WORD]]
loss = []
# i is input index, j is output index
i = 0
j = 0
# go through alignments, progress j when new output is introduced, progress i when new char is seen on lemma (no ~)
# TODO: try sutskever flip trick?
# TODO: attention on the lemma chars/feats could help here?
aligned_lemma, aligned_word = aligned_pair
aligned_lemma += END_WORD
aligned_word += END_WORD
# run through the alignments
for index, (input_char, output_char) in enumerate(zip(aligned_lemma, aligned_word)):
possible_outputs = []
# feedback, i, j, blstm[i], feats
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
# if reached the end word symbol
if output_char == END_WORD:
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
# compute local loss
loss.append(-pc.log(pc.pick(probs, alphabet_index[END_WORD])))
continue
# if there is no prefix, step
if padded_lemma[i] == BEGIN_WORD and aligned_lemma[index] != ALIGN_SYMBOL:
# perform rnn step
# feedback, i, j, blstm[i], feats
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
# compute local loss
loss.append(-pc.log(pc.pick(probs, alphabet_index[STEP])))
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[STEP]]
prev_char_vec = char_lookup[alphabet_index[EPSILON]]
i += 1
# if there is new output
if aligned_word[index] != ALIGN_SYMBOL:
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
# copy i action - maybe model as a single action?
if padded_lemma[i] == aligned_word[j]:
possible_outputs.append(str(i))
possible_outputs.append(padded_lemma[i])
else:
possible_outputs.append(aligned_word[index])
# perform rnn step
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
local_loss = pc.scalarInput(0)
max_output_loss = -pc.log(pc.pick(probs, alphabet_index[possible_outputs[0]]))
max_likelihood_output = possible_outputs[0]
# sum over all correct output possibilities and pick feedback output to be the one with the highest
# probability
for output in possible_outputs:
neg_log_likelihood = -pc.log(pc.pick(probs, alphabet_index[output]))
if neg_log_likelihood < max_output_loss:
max_likelihood_output = output
max_output_loss = neg_log_likelihood
local_loss += neg_log_likelihood
loss.append(local_loss)
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[max_likelihood_output]]
prev_char_vec = char_lookup[alphabet_index[aligned_word[index]]]
j += 1
# now check if it's time to progress on input
if i < len(padded_lemma) - 1 and aligned_lemma[index + 1] != ALIGN_SYMBOL:
# perform rnn step
# feedback, i, j, blstm[i], feats
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
s = s.add_input(decoder_input)
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
# compute local loss
loss.append(-pc.log(pc.pick(probs, alphabet_index[STEP])))
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[STEP]]
prev_char_vec = char_lookup[alphabet_index[EPSILON]]
i += 1
# TODO: maybe here a "special" loss function is appropriate?
# loss = esum(loss)
loss = pc.average(loss)
return loss
def predict_output_sequence(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, alphabet_index,
inverse_alphabet_index, feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
# convert characters to matching embeddings, if UNK handle properly
padded_lemma = BEGIN_WORD + lemma + END_WORD
lemma_char_vecs = []
for char in padded_lemma:
try:
lemma_char_vecs.append(char_lookup[alphabet_index[char]])
except KeyError:
# handle UNK
lemma_char_vecs.append(char_lookup[alphabet_index[UNK]])
# convert features to matching embeddings, if UNK handle properly
feat_vecs = []
for feat in sorted(feature_types):
# TODO: is it OK to use same UNK for all feature types? and for unseen feats as well?
# if this feature has a value, take it from the lookup. otherwise use UNK
if feat in feats:
feat_str = feat + ':' + feats[feat]
try:
feat_vecs.append(feat_lookup[feat_index[feat_str]])
except KeyError:
# handle UNK or dropout
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
else:
feat_vecs.append(feat_lookup[feat_index[UNK_FEAT]])
feats_input = pc.concatenate(feat_vecs)
# BiLSTM forward pass
s_0 = encoder_frnn.initial_state()
s = s_0
frnn_outputs = []
for c in lemma_char_vecs:
s = s.add_input(c)
frnn_outputs.append(s.output())
# BiLSTM backward pass
s_0 = encoder_rrnn.initial_state()
s = s_0
rrnn_outputs = []
for c in reversed(lemma_char_vecs):
s = s.add_input(c)
rrnn_outputs.append(s.output())
# BiLTSM outputs
blstm_outputs = []
lemma_char_vecs_len = len(lemma_char_vecs)
for i in xrange(lemma_char_vecs_len):
blstm_outputs.append(pc.concatenate([frnn_outputs[i], rrnn_outputs[lemma_char_vecs_len - i - 1]]))
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
prev_char_vec = char_lookup[alphabet_index[BEGIN_WORD]]
# i is input index, j is output index
i = j = 0
num_outputs = 0
predicted_output_sequence = []
# run the decoder through the sequence and predict characters, twice max prediction as step outputs are added
while num_outputs < MAX_PREDICTION_LEN * 3:
# prepare input vector and perform LSTM step
decoder_input = pc.concatenate([prev_output_vec,
prev_char_vec,
# char_lookup[alphabet_index[str(i)]],
# char_lookup[alphabet_index[str(j)]],
blstm_outputs[i],
feats_input])
s = s.add_input(decoder_input)
# compute softmax probs vector and predict with argmax
decoder_rnn_output = s.output()
probs = pc.softmax(R * decoder_rnn_output + bias)
probs = probs.vec_value()
predicted_output_index = common.argmax(probs)
predicted_output = inverse_alphabet_index[predicted_output_index]
predicted_output_sequence.append(predicted_output)
# check if step or char output to promote i or j.
if predicted_output == STEP:
prev_char_vec = char_lookup[alphabet_index[EPSILON]]
if i < len(padded_lemma) - 1:
i += 1
else:
if predicted_output.isdigit():
# handle copy
# try:
# prev_char_vec = char_lookup[alphabet_index[padded_lemma[i]]]
# except KeyError:
# prev_char_vec = char_lookup[alphabet_index[UNK]]
try:
# this way END_WORD cannot be copied (as it is in the training stage)
if i < len(lemma) + 1:
prev_char_vec = char_lookup[alphabet_index[padded_lemma[i]]]
else:
# if trying to copy from a non-existent index, pad with last lemma character
prev_char_vec = char_lookup[alphabet_index[lemma[-1]]]
except KeyError:
prev_char_vec = char_lookup[alphabet_index[UNK]]
else:
# handle char
prev_char_vec = char_lookup[predicted_output_index]
j += 1
num_outputs += 1
# check if reached end of word
if predicted_output_sequence[-1] == END_WORD:
break
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[predicted_output_index]
# remove the end word symbol
return predicted_output_sequence[0:-1]
def predict_output_sequence(model, encoder_frnn, encoder_rrnn, decoder_rnn,
lemma, feats, alphabet_index,
inverse_alphabet_index, feat_index, feature_types):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
W_c = pc.parameter(model["W_c"])
W__a = pc.parameter(model["W__a"])
U__a = pc.parameter(model["U__a"])
v__a = pc.parameter(model["v__a"])
# encode the lemma
blstm_outputs = encode_chars(alphabet_index, char_lookup, encoder_frnn,
encoder_rrnn, lemma)
# convert features to matching embeddings, if UNK handle properly
feats_input = encode_feats(feat_index, feat_lookup, feats, feature_types)
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
i = 0
predicted_sequence = []
# run the decoder through the sequence and predict characters
while i < MAX_PREDICTION_LEN:
# get current h of the decoder
s = s.add_input(pc.concatenate([prev_output_vec, feats_input]))
decoder_rnn_output = s.output()
# perform attention step
attention_output_vector, alphas, W = task1_attention_implementation.attend(
blstm_outputs, decoder_rnn_output, W_c, v__a, W__a, U__a)
# compute output probabilities
# print 'computing readout layer...'
readout = R * attention_output_vector + bias
# find best candidate output
probs = pc.softmax(readout)
next_char_index = common.argmax(probs.vec_value())
predicted_sequence.append(inverse_alphabet_index[next_char_index])
# check if reached end of word
if predicted_sequence[-1] == END_WORD:
break
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[next_char_index]
i += 1
# remove the end word symbol
return predicted_sequence[0:-1]
def compute_loss(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats, word, alphabet_index, feat_index,
feature_types, alignment):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
W_c = pc.parameter(model["W_c"])
W__a = pc.parameter(model["W__a"])
U__a = pc.parameter(model["U__a"])
v__a = pc.parameter(model["v__a"])
template = task1_ms2s.generate_template_from_alignment(alignment)
blstm_outputs = task1_attention_implementation.encode_feats_and_chars(alphabet_index, char_lookup, encoder_frnn, encoder_rrnn, feat_index,
feat_lookup, feats, feature_types, lemma)
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
prev_char_vec = char_lookup[alphabet_index[BEGIN_WORD]]
loss = []
padded_word = word + END_WORD
padded_template = template + [END_WORD]
# run the decoder through the output sequence and aggregate loss
for i, output_char in enumerate(padded_word):
# find all possible actions - copy from index, output specific character etc.
possible_outputs = list(set([padded_template[i]]))# + [output_char]))
# get current h of the decoder
s = s.add_input(pc.concatenate([prev_output_vec, prev_char_vec]))
decoder_rnn_output = s.output()
attention_output_vector, alphas, W = task1_attention_implementation.attend(blstm_outputs, decoder_rnn_output,
W_c, v__a, W__a, U__a)
# compute output probabilities
# print 'computing readout layer...'
readout = R * attention_output_vector + bias
# choose which feedback based on minimum neg. log likelihood: initialize with the character loss
min_neg_log_loss = pc.pickneglogsoftmax(readout, alphabet_index[output_char])
prev_output_char = output_char
prev_output_action = output_char
for output in possible_outputs:
current_loss = pc.pickneglogsoftmax(readout, alphabet_index[output])
# append the loss of all options
loss.append(current_loss)
if current_loss < min_neg_log_loss:
min_neg_log_loss = current_loss
prev_output_action = output
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[prev_output_action]]
prev_char_vec = char_lookup[alphabet_index[prev_output_char]]
total_sequence_loss = pc.esum(loss)
# loss = average(loss)
return total_sequence_loss
def compute_loss(model, encoder_frnn, encoder_rrnn, decoder_rnn, lemma, feats,
word, alphabet_index, feat_index, feature_types, alignment):
pc.renew_cg()
# read the parameters
char_lookup = model["char_lookup"]
feat_lookup = model["feat_lookup"]
R = pc.parameter(model["R"])
bias = pc.parameter(model["bias"])
W_c = pc.parameter(model["W_c"])
W__a = pc.parameter(model["W__a"])
U__a = pc.parameter(model["U__a"])
v__a = pc.parameter(model["v__a"])
template = task1_ms2s.generate_template_from_alignment(alignment)
blstm_outputs = encode_chars(alphabet_index, char_lookup, encoder_frnn,
encoder_rrnn, lemma)
# initialize the decoder rnn
s_0 = decoder_rnn.initial_state()
s = s_0
# convert features to matching embeddings, if UNK handle properly
feats_input = encode_feats(feat_index, feat_lookup, feats, feature_types)
# set prev_output_vec for first lstm step as BEGIN_WORD
prev_output_vec = char_lookup[alphabet_index[BEGIN_WORD]]
prev_char_vec = char_lookup[alphabet_index[BEGIN_WORD]]
loss = []
padded_word = word + END_WORD
padded_template = template + [END_WORD]
# run the decoder through the output sequence and aggregate loss
for i, output_char in enumerate(padded_word):
# find all possible actions - copy from index, output specific character etc.
possible_outputs = list(set([padded_template[i]] + [output_char]))
# get current h of the decoder
s = s.add_input(
pc.concatenate([prev_output_vec, prev_char_vec, feats_input]))
decoder_rnn_output = s.output()
attention_output_vector, alphas, W = task1_attention_implementation.attend(
blstm_outputs, decoder_rnn_output, W_c, v__a, W__a, U__a)
# compute output probabilities
# print 'computing readout layer...'
readout = R * attention_output_vector + bias
# choose which feedback based on minimum neg. log likelihood: initialize with the character loss
min_neg_log_loss = pc.pickneglogsoftmax(readout,
alphabet_index[output_char])
prev_output_char = output_char
prev_output_action = output_char
for output in possible_outputs:
current_loss = pc.pickneglogsoftmax(readout,
alphabet_index[output])
# append the loss of all options
loss.append(current_loss)
if current_loss < min_neg_log_loss:
min_neg_log_loss = current_loss
prev_output_action = output
# prepare for the next iteration - "feedback"
prev_output_vec = char_lookup[alphabet_index[prev_output_action]]
prev_char_vec = char_lookup[alphabet_index[prev_output_char]]
total_sequence_loss = pc.esum(loss)
# loss = average(loss)
return total_sequence_loss