class DefaultTranslator(Translator, Serializable, Reportable):
'''
A default translator based on attentional sequence-to-sequence models.
Args:
src_reader (InputReader): A reader for the source side.
trg_reader (InputReader): A reader for the target side.
src_embedder (Embedder): A word embedder for the input language
encoder (Transducer): An encoder to generate encoded inputs
attender (Attender): An attention module
trg_embedder (Embedder): A word embedder for the output language
decoder (Decoder): A decoder
inference (SimpleInference): The default inference strategy used for this model
calc_global_fertility (bool):
calc_attention_entropy (bool):
'''
yaml_tag = '!DefaultTranslator'
@register_xnmt_handler
@serializable_init
def __init__(self,
src_reader,
trg_reader,
src_embedder=bare(SimpleWordEmbedder),
encoder=bare(BiLSTMSeqTransducer),
attender=bare(MlpAttender),
trg_embedder=bare(SimpleWordEmbedder),
decoder=bare(MlpSoftmaxDecoder),
inference=bare(SimpleInference),
calc_global_fertility=False,
calc_attention_entropy=False):
self.src_reader = src_reader
self.trg_reader = trg_reader
self.src_embedder = src_embedder
self.encoder = encoder
self.attender = attender
self.trg_embedder = trg_embedder
self.decoder = decoder
self.calc_global_fertility = calc_global_fertility
self.calc_attention_entropy = calc_attention_entropy
self.inference = inference
def shared_params(self):
return [
set([".src_embedder.emb_dim", ".encoder.input_dim"]),
set([
".encoder.hidden_dim", ".attender.input_dim",
".decoder.input_dim"
]),
set([".attender.state_dim", ".decoder.rnn_layer.hidden_dim"]),
set([".trg_embedder.emb_dim", ".decoder.trg_embed_dim"])
]
def initialize_generator(self, **kwargs):
# TODO: refactor?
if kwargs.get("len_norm_type", None) is None:
len_norm = xnmt.length_normalization.NoNormalization()
else:
len_norm = initialize_if_needed(kwargs["len_norm_type"])
search_args = {}
if kwargs.get("max_len", None) is not None:
search_args["max_len"] = kwargs["max_len"]
if kwargs.get("beam", None) is None:
self.search_strategy = GreedySearch(**search_args)
else:
search_args["beam_size"] = kwargs.get("beam", 1)
search_args["len_norm"] = len_norm
self.search_strategy = BeamSearch(**search_args)
self.report_path = kwargs.get("report_path", None)
self.report_type = kwargs.get("report_type", None)
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 generate(self, src, idx, src_mask=None, forced_trg_ids=None):
if not xnmt.batcher.is_batched(src):
src = xnmt.batcher.mark_as_batch([src])
else:
assert src_mask is not None
outputs = []
for sents in src:
self.start_sent(src)
embeddings = self.src_embedder.embed_sent(src)
encodings = self.encoder(embeddings)
self.attender.init_sent(encodings)
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))
output_actions, score = self.search_strategy.generate_output(
self.decoder,
self.attender,
self.trg_embedder,
dec_state,
src_length=len(sents),
forced_trg_ids=forced_trg_ids)
# In case of reporting
if self.report_path is not None:
if self.reporting_src_vocab:
src_words = [self.reporting_src_vocab[w] for w in sents]
else:
src_words = ['' for w in sents]
trg_words = [
self.trg_vocab[w] for w in output_actions.word_ids
]
# Attentions
attentions = output_actions.attentions
if type(attentions) == dy.Expression:
attentions = attentions.npvalue()
elif type(attentions) == list:
attentions = np.concatenate(
[x.npvalue() for x in attentions], axis=1)
elif type(attentions) != np.ndarray:
raise RuntimeError(
"Illegal type for attentions in translator report: {}".
format(type(attentions)))
# Segmentation
segment = self.get_report_resource("segmentation")
if segment is not None:
segment = [int(x[0]) for x in segment]
src_inp = [
x[0] for x in self.encoder.apply_segmentation(
src_words, segment)
]
else:
src_inp = src_words
# Other Resources
self.set_report_input(idx, src_inp, trg_words, attentions)
self.set_report_resource("src_words", src_words)
self.set_report_path('{}.{}'.format(self.report_path,
str(idx)))
self.generate_report(self.report_type)
# Append output to the outputs
outputs.append(
TextOutput(actions=output_actions.word_ids,
vocab=self.trg_vocab
if hasattr(self, "trg_vocab") else None,
score=score))
self.outputs = outputs
return outputs
def global_fertility(self, a):
return dy.sum_elems(dy.square(1 - dy.esum(a)))
def attention_entropy(self, a):
EPS = 1e-10
entropy = []
for a_i in a:
a_i += EPS
entropy.append(dy.cmult(a_i, dy.log(a_i)))
return -dy.sum_elems(dy.esum(entropy))
def set_reporting_src_vocab(self, src_vocab):
"""
Sets source vocab for reporting purposes.
Args:
src_vocab (Vocab):
"""
self.reporting_src_vocab = src_vocab
@register_xnmt_event_assign
def html_report(self, context=None):
assert (context is None)
idx, src, trg, att = self.get_report_input()
path_to_report = self.get_report_path()
html = etree.Element('html')
head = etree.SubElement(html, 'head')
title = etree.SubElement(head, 'title')
body = etree.SubElement(html, 'body')
report = etree.SubElement(body, 'h1')
if idx is not None:
title.text = report.text = 'Translation Report for Sentence %d' % (
idx)
else:
title.text = report.text = 'Translation Report'
main_content = etree.SubElement(body, 'div', name='main_content')
# Generating main content
captions = ["Source Words", "Target Words"]
inputs = [src, trg]
for caption, inp in zip(captions, inputs):
if inp is None: continue
sent = ' '.join(inp)
p = etree.SubElement(main_content, 'p')
p.text = f"{caption}: {sent}"
# Generating attention
if not any([src is None, trg is None, att is None]):
attention = etree.SubElement(main_content, 'p')
att_text = etree.SubElement(attention, 'b')
att_text.text = "Attention:"
etree.SubElement(attention, 'br')
attention_file = f"{path_to_report}.attention.png"
xnmt.plot.plot_attention(src, trg, att, file_name=attention_file)
# return the parent context to be used as child context
return html
@handle_xnmt_event
def on_file_report(self):
idx, src, trg, attn = self.get_report_input()
assert attn.shape == (len(src), len(trg))
col_length = []
for word in trg:
col_length.append(max(len(word), 6))
col_length.append(max(len(x) for x in src))
with open(self.get_report_path() + ".attention.txt",
encoding='utf-8',
mode='w') as attn_file:
for i in range(len(src) + 1):
if i == 0:
words = trg + [""]
else:
words = ["%.4f" % (f) for f in attn[i - 1]] + [src[i - 1]]
str_format = ""
for length in col_length:
str_format += "{:%ds}" % (length + 2)
print(str_format.format(*words), file=attn_file)
class DefaultTranslator(Translator, Serializable, Reportable):
'''
A default translator based on attentional sequence-to-sequence models.
'''
yaml_tag = u'!DefaultTranslator'
def __init__(self, src_embedder, encoder, attender, trg_embedder, decoder):
'''Constructor.
:param src_embedder: A word embedder for the input language
:param encoder: An encoder to generate encoded inputs
:param attender: An attention module
:param trg_embedder: A word embedder for the output language
:param decoder: A decoder
'''
register_handler(self)
self.src_embedder = src_embedder
self.encoder = encoder
self.attender = attender
self.trg_embedder = trg_embedder
self.decoder = decoder
def shared_params(self):
return [
set(["src_embedder.emb_dim", "encoder.input_dim"]),
set([
"encoder.hidden_dim", "attender.input_dim", "decoder.input_dim"
]),
set(["attender.state_dim", "decoder.lstm_dim"]),
set(["trg_embedder.emb_dim", "decoder.trg_embed_dim"])
]
def initialize_generator(self, **kwargs):
if kwargs.get("len_norm_type", None) is None:
len_norm = xnmt.length_normalization.NoNormalization()
else:
len_norm = xnmt.serializer.YamlSerializer().initialize_if_needed(
kwargs["len_norm_type"])
search_args = {}
if kwargs.get("max_len", None) is not None:
search_args["max_len"] = kwargs["max_len"]
if kwargs.get("beam", None) is None:
self.search_strategy = GreedySearch(**search_args)
else:
search_args["beam_size"] = kwargs.get("beam", 1)
search_args["len_norm"] = len_norm
self.search_strategy = BeamSearch(**search_args)
self.report_path = kwargs.get("report_path", None)
self.report_type = kwargs.get("report_type", None)
def initialize_training_strategy(self, training_strategy):
self.loss_calculator = training_strategy
def calc_loss(self, src, trg):
"""
:param src: source sequence (unbatched, or batched + padded)
:param trg: target sequence (unbatched, or batched + padded); losses will be accumulated only if trg_mask[batch,pos]==0, or no mask is set
:returns: (possibly batched) loss expression
"""
assert hasattr(self, "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))
return self.loss_calculator(self, dec_state, src, trg)
def generate(self, src, idx, src_mask=None, forced_trg_ids=None):
if not xnmt.batcher.is_batched(src):
src = xnmt.batcher.mark_as_batch([src])
else:
assert src_mask is not None
outputs = []
for sents in src:
self.start_sent(src)
embeddings = self.src_embedder.embed_sent(src)
encodings = self.encoder(embeddings)
self.attender.init_sent(encodings)
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))
output_actions, score = self.search_strategy.generate_output(
self.decoder,
self.attender,
self.trg_embedder,
dec_state,
src_length=len(sents),
forced_trg_ids=forced_trg_ids)
# In case of reporting
if self.report_path is not None:
src_words = [self.reporting_src_vocab[w] for w in sents]
trg_words = [self.trg_vocab[w] for w in output_actions[1:]]
attentions = self.attender.attention_vecs
self.set_report_input(idx, src_words, trg_words, attentions)
self.set_report_resource("src_words", src_words)
self.set_report_path('{}.{}'.format(self.report_path,
str(idx)))
self.generate_report(self.report_type)
# Append output to the outputs
outputs.append(
TextOutput(actions=output_actions,
vocab=self.trg_vocab
if hasattr(self, "trg_vocab") else None,
score=score))
return outputs
def set_reporting_src_vocab(self, src_vocab):
"""
Sets source vocab for reporting purposes.
"""
self.reporting_src_vocab = src_vocab
@register_xnmt_event_assign
def html_report(self, context=None):
assert (context is None)
idx, src, trg, att = self.get_report_input()
path_to_report = self.get_report_path()
html = etree.Element('html')
head = etree.SubElement(html, 'head')
title = etree.SubElement(head, 'title')
body = etree.SubElement(html, 'body')
report = etree.SubElement(body, 'h1')
if idx is not None:
title.text = report.text = 'Translation Report for Sentence %d' % (
idx)
else:
title.text = report.text = 'Translation Report'
main_content = etree.SubElement(body, 'div', name='main_content')
# Generating main content
captions = [u"Source Words", u"Target Words"]
inputs = [src, trg]
for caption, inp in six.moves.zip(captions, inputs):
if inp is None: continue
sent = ' '.join(inp)
p = etree.SubElement(main_content, 'p')
p.text = u"{}: {}".format(caption, sent)
# Generating attention
if not any([src is None, trg is None, att is None]):
attention = etree.SubElement(main_content, 'p')
att_text = etree.SubElement(attention, 'b')
att_text.text = "Attention:"
etree.SubElement(attention, 'br')
attention_file = u"{}.attention.png".format(path_to_report)
if type(att) == dy.Expression:
attentions = att.npvalue()
elif type(att) == list:
attentions = np.concatenate([x.npvalue() for x in att], axis=1)
elif type(att) != np.ndarray:
raise RuntimeError(
"Illegal type for attentions in translator report: {}".
format(type(attentions)))
plot.plot_attention(src, trg, attentions, file_name=attention_file)
# return the parent context to be used as child context
return html