def eval(self):
if self.src_data == None:
self.src_data, self.ref_data, self.src_batches, self.ref_batches = \
xnmt.input_reader.read_parallel_corpus(self.model.src_reader, self.model.trg_reader,
self.src_file, self.ref_file, batcher=self.batcher,
max_src_len=self.max_src_len, max_trg_len=self.max_trg_len)
loss_val = LossScalarBuilder()
ref_words_cnt = 0
for src, trg in zip(self.src_batches, self.ref_batches):
dy.renew_cg(immediate_compute=settings.IMMEDIATE_COMPUTE, check_validity=settings.CHECK_VALIDITY)
loss_builder = LossBuilder()
standard_loss = self.model.calc_loss(src, trg, self.loss_calculator)
additional_loss = self.model.calc_additional_loss(standard_loss)
loss_builder.add_loss("standard_loss", standard_loss)
loss_builder.add_loss("additional_loss", additional_loss)
ref_words_cnt += self.model.trg_reader.count_words(trg)
loss_val += loss_builder.get_loss_stats()
loss_stats = {k: v/ref_words_cnt for k, v in loss_val.items()}
try:
return LossScore(loss_stats[self.model.get_primary_loss()], loss_stats=loss_stats, desc=self.desc), ref_words_cnt
except KeyError:
raise RuntimeError("Did you wrap your loss calculation with LossBuilder({'primary_loss': loss_value}) ?")
def on_calc_additional_loss(self, reward):
if not self.learn_segmentation:
return None
ret = LossBuilder()
if self.length_prior_alpha > 0:
reward += self.segment_length_prior * self.length_prior_alpha
reward = dy.cdiv(reward - dy.mean_batches(reward),
dy.std_batches(reward))
# Baseline Loss
if self.use_baseline:
baseline_loss = []
for i, baseline in enumerate(self.bs):
baseline_loss.append(dy.squared_distance(reward, baseline))
ret.add_loss("Baseline", dy.esum(baseline_loss))
# Reinforce Loss
lmbd = self.lmbd.get_value(self.warmup_counter)
if lmbd > 0.0:
reinforce_loss = []
# Calculating the loss of the baseline and reinforce
for i in range(len(self.segment_decisions)):
ll = dy.pick_batch(self.segment_logsoftmaxes[i],
self.segment_decisions[i])
if self.use_baseline:
r_i = reward - self.bs[i]
else:
r_i = reward
reinforce_loss.append(dy.logistic(r_i) * ll)
ret.add_loss("Reinforce", -dy.esum(reinforce_loss) * lmbd)
# Total Loss
return ret
def training_step(self, src, trg):
"""
Performs forward pass, backward pass, parameter update for the given minibatch
"""
loss_builder = LossBuilder()
standard_loss = self.model.calc_loss(src, trg, self.loss_calculator)
additional_loss = self.model.calc_additional_loss(standard_loss)
loss_builder.add_loss("standard_loss", standard_loss)
loss_builder.add_loss("additional_loss", additional_loss)
return loss_builder
def compute_dev_loss(self):
loss_builder = LossBuilder()
trg_words_cnt = 0
for src, trg in zip(self.dev_src, self.dev_trg):
dy.renew_cg()
standard_loss = self.model.calc_loss(src, trg)
loss_builder.add_loss("loss", standard_loss)
trg_words_cnt += self.logger.count_trg_words(trg)
loss_builder.compute()
return trg_words_cnt, LossScore(loss_builder.sum() / trg_words_cnt)
def calc_loss(self, src, trg, loss_calculator):
sub_losses = collections.defaultdict(list)
for model in self.models:
for loss_name, loss in model.calc_loss(src, trg, loss_calculator).loss_values.items():
sub_losses[loss_name].append(loss)
model_loss = LossBuilder()
for loss_name, losslist in sub_losses.items():
# TODO: dy.average(losslist) _or_ dy.esum(losslist) / len(self.models) ?
# -- might not be the same if not all models return all losses
model_loss.add_loss(loss_name, dy.average(losslist))
return model_loss
def training_step(self, src, trg):
"""
Performs forward pass, backward pass, parameter update for the given minibatch
"""
loss_builder = LossBuilder()
standard_loss = self.model.calc_loss(src, trg, self.loss_calculator)
additional_loss = self.model.calc_additional_loss(standard_loss)
loss_builder.add_loss("standard_loss", standard_loss)
loss_builder.add_loss("additional_loss", additional_loss)
loss_value = loss_builder.compute()
self.logger.update_epoch_loss(src, trg, loss_builder.get_loss_stats())
self.logger.report_train_process()
return loss_value
def calc_loss(self, src, trg, loss_calculator):
self.start_sent(src)
embeddings = self.src_embedder.embed_sent(src)
encodings = self.encoder(embeddings)
self.attender.init_sent(encodings)
# Initialize the hidden state from the encoder
ss = mark_as_batch([Vocab.SS] *
len(src)) if is_batched(src) else Vocab.SS
dec_state = self.decoder.initial_state(self.encoder.get_final_states(),
self.trg_embedder.embed(ss))
# Compose losses
model_loss = LossBuilder()
model_loss.add_loss("mle", loss_calculator(self, dec_state, src, trg))
if self.calc_global_fertility or self.calc_attention_entropy:
# philip30: I assume that attention_vecs is already masked src wisely.
# Now applying the mask to the target
masked_attn = self.attender.attention_vecs
if trg.mask is not None:
trg_mask = trg.mask.get_active_one_mask().transpose()
masked_attn = [
dy.cmult(attn, dy.inputTensor(mask, batched=True))
for attn, mask in zip(masked_attn, trg_mask)
]
if self.calc_global_fertility:
model_loss.add_loss("fertility",
self.global_fertility(masked_attn))
if self.calc_attention_entropy:
model_loss.add_loss("H(attn)", self.attention_entropy(masked_attn))
return model_loss
def training_step(self, src, trg):
"""
Performs forward pass, backward pass, parameter update for the given minibatch
"""
loss_builder = LossBuilder()
standard_loss = self.model.calc_loss(src, trg, self.loss_calculator)
if standard_loss.__class__ == LossBuilder:
loss = None
for loss_name, loss_expr in standard_loss.loss_nodes:
loss_builder.add_loss(loss_name, loss_expr)
loss = loss_expr if not loss else loss + loss_expr
standard_loss = loss
else:
loss_builder.add_loss("loss", standard_loss)
additional_loss = self.model.calc_additional_loss(
dy.nobackprop(-standard_loss))
if additional_loss != None:
loss_builder.add_loss("additional_loss", additional_loss)
loss_value = loss_builder.compute()
self.logger.update_epoch_loss(src, trg, loss_builder)
self.logger.report_train_process()
return loss_value
def __call__(self, translator, dec_state, src, trg):
# TODO: apply trg.mask ?
samples = []
logsofts = []
self.bs = []
done = [False for _ in range(len(trg))]
for _ in range(self.sample_length):
dec_state.context = translator.attender.calc_context(dec_state.rnn_state.output())
if self.use_baseline:
h_t = dy.tanh(translator.decoder.context_projector(dy.concatenate([dec_state.rnn_state.output(), dec_state.context])))
self.bs.append(self.baseline(dy.nobackprop(h_t)))
logsoft = dy.log_softmax(translator.decoder.get_scores(dec_state))
sample = logsoft.tensor_value().categorical_sample_log_prob().as_numpy()[0]
# Keep track of previously sampled EOS
sample = [sample_i if not done_i else Vocab.ES for sample_i, done_i in zip(sample, done)]
# Appending and feeding in the decoder
logsoft = dy.pick_batch(logsoft, sample)
logsofts.append(logsoft)
samples.append(sample)
dec_state = translator.decoder.add_input(dec_state, translator.trg_embedder.embed(xnmt.batcher.mark_as_batch(sample)))
# Check if we are done.
done = list(six.moves.map(lambda x: x == Vocab.ES, sample))
if all(done):
break
samples = np.stack(samples, axis=1).tolist()
self.eval_score = []
for trg_i, sample_i in zip(trg, samples):
# Removing EOS
try:
idx = sample_i.index(Vocab.ES)
sample_i = sample_i[:idx]
except ValueError:
pass
try:
idx = trg_i.words.index(Vocab.ES)
trg_i.words = trg_i.words[:idx]
except ValueError:
pass
# Calculate the evaluation score
score = 0 if not len(sample_i) else self.evaluation_metric.evaluate_fast(trg_i.words, sample_i)
self.eval_score.append(score)
self.true_score = dy.inputTensor(self.eval_score, batched=True)
loss = LossBuilder()
if self.use_baseline:
for i, (score, _) in enumerate(zip(self.bs, logsofts)):
logsofts[i] = dy.cmult(logsofts[i], score - self.true_score)
loss.add_loss("Reinforce", dy.sum_elems(dy.esum(logsofts)))
else:
loss.add_loss("Reinforce", dy.sum_elems(dy.cmult(-self.true_score, dy.esum(logsofts))))
if self.use_baseline:
baseline_loss = []
for bs in self.bs:
baseline_loss.append(dy.squared_distance(self.true_score, bs))
loss.add_loss("Baseline", dy.sum_elems(dy.esum(baseline_loss)))
return loss
def on_calc_additional_loss(self, translator_loss):
if not self.learn_segmentation or self.segment_decisions is None:
return None
reward = -translator_loss["mle"]
if not self.log_reward:
reward = dy.exp(reward)
reward = dy.nobackprop(reward)
# Make sure that reward is not scalar, but rather based on the each batch item
assert reward.dim()[1] == len(self.src_sent)
# Mask
enc_mask = self.enc_mask.get_active_one_mask().transpose() if self.enc_mask is not None else None
# Compose the lose
ret = LossBuilder()
## Length prior
alpha = self.length_prior_alpha.value() if self.length_prior_alpha is not None else 0
if alpha > 0:
reward += self.segment_length_prior * alpha
# reward z-score normalization
if self.z_normalization:
reward = dy.cdiv(reward-dy.mean_batches(reward), dy.std_batches(reward) + EPS)
## Baseline Loss
if self.use_baseline:
baseline_loss = []
for i, baseline in enumerate(self.bs):
loss = dy.squared_distance(reward, baseline)
if enc_mask is not None:
loss = dy.cmult(dy.inputTensor(enc_mask[i], batched=True), loss)
baseline_loss.append(loss)
ret.add_loss("Baseline", dy.esum(baseline_loss))
if self.print_sample:
print(dy.exp(self.segment_logsoftmaxes[i]).npvalue().transpose()[0])
## Reinforce Loss
lmbd = self.lmbd.value()
if lmbd > 0.0:
reinforce_loss = []
# Calculating the loss of the baseline and reinforce
for i in range(len(self.segment_decisions)):
ll = dy.pick_batch(self.segment_logsoftmaxes[i], self.segment_decisions[i])
if self.use_baseline:
r_i = reward - dy.nobackprop(self.bs[i])
else:
r_i = reward
if enc_mask is not None:
ll = dy.cmult(dy.inputTensor(enc_mask[i], batched=True), ll)
reinforce_loss.append(r_i * -ll)
loss = dy.esum(reinforce_loss) * lmbd
ret.add_loss("Reinforce", loss)
if self.confidence_penalty:
ls_loss = self.confidence_penalty(self.segment_logsoftmaxes, enc_mask)
ret.add_loss("Confidence Penalty", ls_loss)
# Total Loss
return ret
def one_epoch(self, update_weights=True):
"""
:param update_weights: Whether to perform backward pass & update weights (useful for debugging)
"""
self.logger.new_epoch()
if self.args["reload_command"] is not None:
self._augment_data_next_epoch()
self.model.set_train(update_weights)
order = list(range(0, len(self.train_src)))
np.random.shuffle(order)
for batch_num in order:
src = self.train_src[batch_num]
trg = self.train_trg[batch_num]
# Loss calculation
dy.renew_cg()
loss_builder = LossBuilder()
standard_loss = self.model.calc_loss(src, trg)
if standard_loss.__class__ == LossBuilder:
loss = None
for loss_name, loss_expr in standard_loss.loss_nodes:
loss_builder.add_loss(loss_name, loss_expr)
loss = loss_expr if not loss else loss + loss_expr
standard_loss = loss
else:
loss_builder.add_loss("loss", standard_loss)
additional_loss = self.model.calc_additional_loss(
dy.nobackprop(-standard_loss))
if additional_loss != None:
loss_builder.add_loss("additional_loss", additional_loss)
# Log the loss sum
loss_value = loss_builder.compute()
self.logger.update_epoch_loss(src, trg, loss_builder)
if update_weights:
loss_value.backward()
self.trainer.update()
# Devel reporting
self.logger.report_train_process()
if self.logger.should_report_dev():
self.dev_evaluation()
self.model.new_epoch()
def __call__(self, translator, initial_state, src, trg):
# TODO(philip30): currently only using the best hypothesis / first sample for reinforce loss
# A small further implementation is needed if we want to do reinforce with multiple samples.
search_output = translator.search_strategy.generate_output(
translator, initial_state)[0]
# Calculate evaluation scores
self.eval_score = []
for trg_i, sample_i in zip(trg, search_output.word_ids):
# Removing EOS
sample_i = self.remove_eos(sample_i.tolist())
ref_i = self.remove_eos(trg_i.words)
# Evaluating
if len(sample_i) == 0:
score = 0
else:
score = self.evaluation_metric.evaluate(ref_i, sample_i) * \
(-1 if self.inv_eval else 1)
self.eval_score.append(score)
self.true_score = dy.inputTensor(self.eval_score, batched=True)
# Composing losses
loss = LossBuilder()
if self.use_baseline:
baseline_loss = []
losses = []
for state, logsoft, mask in zip(search_output.state,
search_output.logsoftmaxes,
search_output.mask):
bs_score = self.baseline(state)
baseline_loss.append(
dy.squared_distance(self.true_score, bs_score))
loss_i = dy.cmult(logsoft, self.true_score - bs_score)
losses.append(
dy.cmult(loss_i, dy.inputTensor(mask, batched=True)))
loss.add_loss("reinforce", dy.sum_elems(dy.esum(losses)))
loss.add_loss("reinf_baseline",
dy.sum_elems(dy.esum(baseline_loss)))
else:
loss.add_loss(
"reinforce",
dy.sum_elems(dy.cmult(self.true_score, dy.esum(logsofts))))
return loss
def calc_loss(self, src, trg, loss_calculator):
self.start_sent(src)
tokens = [x[0] for x in src]
transitions = [x[1] for x in src]
print("Current Batch: " + str(len(tokens)) + " pairs.\n")
is_batched = xnmt.batcher.is_batched(src)
tokens = xnmt.batcher.mark_as_batch(tokens)
embeddings = self.src_embedder.embed_sent(tokens)
encodings = self.encoder(embeddings, transitions)
self.attender.init_sent(encodings)
#import pdb;pdb.set_trace()
# Initialize the hidden state from the encoder
ss = mark_as_batch(
[Vocab.SS] *
len(tokens)) if xnmt.batcher.is_batched(src) else Vocab.SS
dec_state = self.decoder.initial_state(self.encoder._final_states,
self.trg_embedder.embed(ss))
# Compose losses
model_loss = LossBuilder()
loss, wer = loss_calculator(self, dec_state, src, trg)
model_loss.add_loss("mle", loss)
print("wer_b:" + str(wer))
if self.calc_global_fertility or self.calc_attention_entropy:
# philip30: I assume that attention_vecs is already masked src wisely.
# Now applying the mask to the target
masked_attn = self.attender.attention_vecs
if trg.mask is not None:
trg_mask = trg.mask.get_active_one_mask().transpose()
masked_attn = [
dy.cmult(attn, dy.inputTensor(mask, batched=True))
for attn, mask in zip(masked_attn, trg_mask)
]
if self.calc_global_fertility:
model_loss.add_loss("fertility",
self.global_fertility(masked_attn))
if self.calc_attention_entropy:
model_loss.add_loss("H(attn)", self.attention_entropy(masked_attn))
return model_loss