def predict_batch(self, words_batch):
dynet.renew_cg()
length = max(len(words) for words in words_batch)
word_ids = np.zeros((length, len(words_batch)), dtype='int32')
for j, words in enumerate(words_batch):
for i, word in enumerate(words):
word_ids[i, j] = self.vw.w2i.get(word, self.UNK)
wembs = [dynet.lookup_batch(self._E, word_ids[i]) for i in range(length)]
f_state = self._fwd_lstm.initial_state()
b_state = self._bwd_lstm.initial_state()
fw = [x.output() for x in f_state.add_inputs(wembs)]
bw = [x.output() for x in b_state.add_inputs(reversed(wembs))]
H = dynet.parameter(self._pH)
O = dynet.parameter(self._pO)
tags_batch = [[] for _ in range(len(words_batch))]
for i, (f, b) in enumerate(zip(fw, reversed(bw))):
r_t = O * (dynet.tanh(H * dynet.concatenate([f, b])))
out = dynet.softmax(r_t).npvalue()
for j in range(len(words_batch)):
tags_batch[j].append(self.vt.i2w[np.argmax(out.T[j])])
return tags_batch
def __attention_mlp(self, h_fs_matrix, h_e, F):
W1_att_f = dy.parameter(self.W1_att_f)
W1_att_e = dy.parameter(self.W1_att_e)
w2_att = dy.parameter(self.w2_att)
# Calculate the alignment score vector
# Hint: Can we make this more efficient?
a_t = self._mlp(W1_att_f, W1_att_e, w2_att, h_fs_matrix, h_e, F)
alignment = dy.softmax(a_t)
c_t = h_fs_matrix * alignment
return alignment, c_t
def attend(self, input_mat, state, w1dt, input_len, batch_size):
global attention_w2
global attention_v
w2 = dy.parameter(attention_w2)
v = dy.parameter(attention_v)
w2dt = w2 * dy.concatenate(list(state.s()))
unnormalized = dy.transpose(v * dy.tanh(dy.colwise_add(w1dt, w2dt)))
unnormalized = dy.reshape(unnormalized, (input_len, ), batch_size)
att_weights = dy.softmax(unnormalized)
context = input_mat * att_weights
return context, att_weights
def attend_batch(input_mat, state, w1dt, batch_size, input_length):
#print "in attend batch"
global attention_w2
global attention_v
w2 = dy.parameter(attention_w2)
v = dy.parameter(attention_v)
#print "Calculating w2dt"
w2dt = w2*dy.concatenate(list(state.s()))
unnormalized = dy.transpose(v * dy.tanh(dy.colwise_add(w1dt, w2dt)))
attention_reshaped = dy.reshape(unnormalized, (input_length, ), batch_size)
att_weights = dy.softmax(attention_reshaped)
context = input_mat * att_weights
return context
def predictNextWord(sentence, builder, wlookup, mR, mB):
dy.renew_cg()
init_state = builder.initial_state()
R = dy.parameter(mR)
bias = dy.parameter(mB)
state = init_state
for cw in sentence:
# assume word is already a word-id
x_t = dy.lookup(wlookup, int(cw))
state = state.add_input(x_t)
y_t = state.output()
r_t = bias + (R * y_t)
prob = dy.softmax(r_t)
return prob
def attend(input_mat, state, w1dt): global attention_w2 global attention_v w2 = dy.parameter(attention_w2) v = dy.parameter(attention_v) # input_mat: (encoder_state x seqlen) => input vecs concatenated as cols # w1dt: (attdim x seqlen) # w2dt: (attdim x attdim) w2dt = w2*dy.concatenate(list(state.s())) # att_weights: (seqlen,) row vector unnormalized = dy.transpose(v * dy.tanh(dy.colwise_add(w1dt, w2dt))) att_weights = dy.softmax(unnormalized) # context: (encoder_state) context = input_mat * att_weights return context
def generate(self, in_seq, enc_fwd_lstm, enc_bwd_lstm, dec_lstm):
embedded = self.embed_sentence(in_seq)
encoded = self.encode_sentence(enc_fwd_lstm, enc_bwd_lstm, embedded)
w = dy.parameter(decoder_w)
b = dy.parameter(decoder_b)
w1 = dy.parameter(attention_w1)
input_mat = dy.concatenate_cols(encoded)
w1dt = w1 * input_mat
last_output_embeddings = output_lookup[EOS]
s = dec_lstm.initial_state()
c_t_previous = dy.vecInput(STATE_SIZE * 2)
out = ''
count_EOS = 0
for i in range(len(in_seq) * 2):
if count_EOS == 2: break
vector = dy.concatenate([last_output_embeddings, c_t_previous])
s = s.add_input(vector)
h_t = s.output()
c_t, alpha_t = self.attend(input_mat, s, w1dt)
h_c_concat = dy.concatenate([h_t, c_t])
out_vector = dy.affine_transform([b, w, h_c_concat])
probs = dy.softmax(out_vector).vec_value()
next_char = probs.index(max(probs))
last_output_embeddings = output_lookup[next_char]
c_t_previous = c_t
if next_char == EOS:
count_EOS += 1
continue
out += " " + id2word_en[next_char]
return out
def __call__(self, words):
dynet.renew_cg()
word_ids = [self.vw.w2i.get(w, self.UNK) for w in words]
wembs = [self._E[w] for w in word_ids]
f_state = self._fwd_lstm.initial_state()
b_state = self._bwd_lstm.initial_state()
fw = [x.output() for x in f_state.add_inputs(wembs)]
bw = [x.output() for x in b_state.add_inputs(reversed(wembs))]
H = dynet.parameter(self._pH)
O = dynet.parameter(self._pO)
tags = []
for i, (f, b) in enumerate(zip(fw, reversed(bw))):
r_t = O * (dynet.tanh(H * dynet.concatenate([f, b])))
out = dynet.softmax(r_t)
tags.append(self.vt.i2w[np.argmax(out.npvalue())])
return tags
def generate(self, in_seq, enc_fwd_lstm, enc_bwd_lstm, dec_lstm):
embedded = self.embed_sentence(in_seq, True)
encoded = self.encode_generation(enc_fwd_lstm, enc_bwd_lstm, embedded)
h_len = len(encoded)
curr_bsize = 1
w = dy.parameter(decoder_w)
b = dy.parameter(decoder_b)
w1 = dy.parameter(attention_w1)
H_source = dy.concatenate_cols(encoded)
s = dec_lstm.initial_state()
ctx_t0 = dy.vecInput(hidden_size * 2)
last_output_embeddings = output_lookup[word2idx_en['<s>']]
w1dt = w1 * H_source
out = []
count_EOS = 0
for i in range(len(in_seq)*2):
if count_EOS == 1: break
# w1dt can be computed and cached once for the entire decoding phase
x = dy.concatenate([ctx_t0, last_output_embeddings])
#print "Attention: Generate"
s = s.add_input(x)
h_t = s.output()
ctx_t, alpha_t = self.attend(H_source, s, w1dt, h_len, curr_bsize)
out_vector = w * dy.concatenate([h_t, ctx_t]) + b
probs = dy.softmax(out_vector).vec_value()
next_char = probs.index(max(probs))
last_output_embeddings = output_lookup[next_char]
if idx2word_en[next_char] == '<EOS>':
count_EOS += 1
continue
out.append(idx2word_en[next_char])
ctx_t0 = ctx_t
return ' '.join(out)
def generate(in_seq, enc_fwd_lstm, enc_bwd_lstm, dec_lstm): #print "in generate" dy.renew_cg() embedded = embed_sentence(in_seq) encoded = encode_batch(enc_fwd_lstm, enc_bwd_lstm, embedded) w = dy.parameter(decoder_w) b = dy.parameter(decoder_b) w1 = dy.parameter(attention_w1) input_mat = dy.concatenate_cols(encoded) w1dt = None last_output_embeddings = output_lookup[BOS] #s = dec_lstm.initial_state([encoded[-1]]) s = dec_lstm.initial_state() c_t_minus_1 = dy.vecInput(state_size*2) out = [] count_EOS = 0 for i in range(len(in_seq)*2): if count_EOS == 1: break # w1dt can be computed and cached once for the entire decoding phase w1dt = w1dt or w1 * input_mat vector = dy.concatenate([last_output_embeddings, c_t_minus_1]) s = s.add_input(vector) h_t = s.output() c_t = attend_batch(input_mat, s, w1dt, 1, 1) out_vector = dy.affine_transform([b, w, dy.concatenate([h_t, c_t])]) probs = dy.softmax(out_vector).vec_value() next_word = probs.index(max(probs)) last_output_embeddings = output_lookup[next_word] c_t_minus_1 = c_t if next_word == EOS: count_EOS += 1 continue out.append(english_word_vocab.i2w[next_word]) return " ".join(out[1:])
