def test_advance_with_all_repeats_gets_blocked(self):
# all beams repeat (beam >= 1 repeat dummy scores)
beam_sz = 5
n_words = 100
repeat_idx = 47
ngram_repeat = 3
beam = Beam(beam_sz, 0, 1, 2, n_best=2,
exclusion_tokens=set(),
global_scorer=GlobalScorerStub(),
block_ngram_repeat=ngram_repeat)
for i in range(ngram_repeat + 4):
# predict repeat_idx over and over again
word_probs = torch.full((beam_sz, n_words), -float('inf'))
word_probs[0, repeat_idx] = 0
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i <= ngram_repeat:
self.assertTrue(
beam.scores.equal(
torch.tensor(
[0] + [-float('inf')] * (beam_sz - 1))))
else:
self.assertTrue(
beam.scores.equal(torch.tensor(
[self.BLOCKED_SCORE] * beam_sz)))
def test_advance_with_some_repeats_gets_blocked(self):
# beam 0 and beam >=2 will repeat (beam >= 2 repeat dummy scores)
beam_sz = 5
n_words = 100
repeat_idx = 47
ngram_repeat = 3
beam = Beam(beam_sz, 0, 1, 2, n_best=2,
exclusion_tokens=set(),
global_scorer=GlobalScorerStub(),
block_ngram_repeat=ngram_repeat)
for i in range(ngram_repeat + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
# on initial round, only predicted scores for beam 0
# matter. Make two predictions. Top one will be repeated
# in beam zero, second one will live on in beam 1.
word_probs[0, repeat_idx] = -0.1
word_probs[0, repeat_idx + i + 1] = -2.3
else:
# predict the same thing in beam 0
word_probs[0, repeat_idx] = 0
# continue pushing around what beam 1 predicts
word_probs[1, repeat_idx + i + 1] = 0
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i <= ngram_repeat:
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
self.assertFalse(beam.scores[1].eq(self.BLOCKED_SCORE))
else:
# now beam 0 dies (along with the others), beam 1 -> beam 0
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
self.assertTrue(
beam.scores[1:].equal(torch.tensor(
[self.BLOCKED_SCORE] * (beam_sz - 1))))
def test_beam_is_done_when_n_best_beams_eos_using_min_length(self):
# this is also a test that when block_ngram_repeat=0,
# repeating is acceptable
beam_sz = 5
n_words = 100
_non_eos_idxs = [47, 51, 13, 88, 99]
valid_score_dist = torch.log_softmax(torch.tensor(
[6., 5., 4., 3., 2., 1.]), dim=0)
min_length = 5
eos_idx = 2
beam = Beam(beam_sz, 0, 1, eos_idx, n_best=2,
exclusion_tokens=set(),
min_length=min_length,
global_scorer=GlobalScorerStub(),
block_ngram_repeat=0)
for i in range(min_length + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
# "best" prediction is eos - that should be blocked
word_probs[0, eos_idx] = valid_score_dist[0]
# include at least beam_sz predictions OTHER than EOS
# that are greater than -1e20
for j, score in zip(_non_eos_idxs, valid_score_dist[1:]):
word_probs[0, j] = score
elif i <= min_length:
# predict eos in beam 1
word_probs[1, eos_idx] = valid_score_dist[0]
# provide beam_sz other good predictions in other beams
for k, (j, score) in enumerate(
zip(_non_eos_idxs, valid_score_dist[1:])):
beam_idx = min(beam_sz-1, k)
word_probs[beam_idx, j] = score
else:
word_probs[0, eos_idx] = valid_score_dist[0]
word_probs[1, eos_idx] = valid_score_dist[0]
# provide beam_sz other good predictions in other beams
for k, (j, score) in enumerate(
zip(_non_eos_idxs, valid_score_dist[1:])):
beam_idx = min(beam_sz-1, k)
word_probs[beam_idx, j] = score
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i < min_length:
self.assertFalse(beam.done)
elif i == min_length:
# beam 1 dies on min_length
self.assertEqual(beam.finished[0][1], beam.min_length + 1)
self.assertEqual(beam.finished[0][2], 1)
self.assertFalse(beam.done)
else: # i > min_length
# beam 0 dies on the step after beam 1 dies
self.assertEqual(beam.finished[1][1], beam.min_length + 2)
self.assertEqual(beam.finished[1][2], 0)
self.assertTrue(beam.done)
def test_doesnt_predict_eos_if_shorter_than_min_len(self):
# beam 0 will always predict EOS. The other beams will predict
# non-eos scores.
# this is also a test that when block_ngram_repeat=0,
# repeating is acceptable
beam_sz = 5
n_words = 100
_non_eos_idxs = [47, 51, 13, 88, 99]
valid_score_dist = torch.log_softmax(torch.tensor(
[6., 5., 4., 3., 2., 1.]), dim=0)
min_length = 5
eos_idx = 2
beam = Beam(beam_sz, 0, 1, eos_idx, n_best=2,
exclusion_tokens=set(),
min_length=min_length,
global_scorer=GlobalScorerStub(),
block_ngram_repeat=0)
for i in range(min_length + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
# "best" prediction is eos - that should be blocked
word_probs[0, eos_idx] = valid_score_dist[0]
# include at least beam_sz predictions OTHER than EOS
# that are greater than -1e20
for j, score in zip(_non_eos_idxs, valid_score_dist[1:]):
word_probs[0, j] = score
else:
# predict eos in beam 0
word_probs[0, eos_idx] = valid_score_dist[0]
# provide beam_sz other good predictions
for k, (j, score) in enumerate(
zip(_non_eos_idxs, valid_score_dist[1:])):
beam_idx = min(beam_sz-1, k)
word_probs[beam_idx, j] = score
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i < min_length:
expected_score_dist = (i+1) * valid_score_dist[1:]
self.assertTrue(beam.scores.allclose(expected_score_dist))
elif i == min_length:
# now the top beam has ended and no others have
# first beam finished had length beam.min_length
self.assertEqual(beam.finished[0][1], beam.min_length + 1)
# first beam finished was 0
self.assertEqual(beam.finished[0][2], 0)
else: # i > min_length
# not of interest, but want to make sure it keeps running
# since only beam 0 terminates and n_best = 2
pass
def test_repeating_excluded_index_does_not_die(self):
# beam 0 and beam >= 2 will repeat (beam 2 repeats excluded idx)
beam_sz = 5
n_words = 100
repeat_idx = 47 # will be repeated and should be blocked
repeat_idx_ignored = 7 # will be repeated and should not be blocked
ngram_repeat = 3
beam = Beam(beam_sz,
0,
1,
2,
n_best=2,
exclusion_tokens=set([repeat_idx_ignored]),
global_scorer=GlobalScorerStub(),
block_ngram_repeat=ngram_repeat)
for i in range(ngram_repeat + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
word_probs[0, repeat_idx] = -0.1
word_probs[0, repeat_idx + i + 1] = -2.3
word_probs[0, repeat_idx_ignored] = -5.0
else:
# predict the same thing in beam 0
word_probs[0, repeat_idx] = 0
# continue pushing around what beam 1 predicts
word_probs[1, repeat_idx + i + 1] = 0
# predict the allowed-repeat again in beam 2
word_probs[2, repeat_idx_ignored] = 0
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i <= ngram_repeat:
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
self.assertFalse(beam.scores[1].eq(self.BLOCKED_SCORE))
self.assertFalse(beam.scores[2].eq(self.BLOCKED_SCORE))
else:
# now beam 0 dies, beam 1 -> beam 0, beam 2 -> beam 1
# and the rest die
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
# since all preds after i=0 are 0, we can check
# that the beam is the correct idx by checking that
# the curr score is the initial score
self.assertTrue(beam.scores[0].eq(-2.3))
self.assertFalse(beam.scores[1].eq(self.BLOCKED_SCORE))
self.assertTrue(beam.scores[1].eq(-5.0))
self.assertTrue(beam.scores[2:].equal(
torch.tensor([self.BLOCKED_SCORE] * (beam_sz - 2))))
def test_repeating_excluded_index_does_not_die(self):
# beam 0 and beam >= 2 will repeat (beam 2 repeats excluded idx)
beam_sz = 5
n_words = 100
repeat_idx = 47 # will be repeated and should be blocked
repeat_idx_ignored = 7 # will be repeated and should not be blocked
ngram_repeat = 3
beam = Beam(beam_sz, 0, 1, 2, n_best=2,
exclusion_tokens=set([repeat_idx_ignored]),
global_scorer=GlobalScorerStub(),
block_ngram_repeat=ngram_repeat)
for i in range(ngram_repeat + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
word_probs[0, repeat_idx] = -0.1
word_probs[0, repeat_idx + i + 1] = -2.3
word_probs[0, repeat_idx_ignored] = -5.0
else:
# predict the same thing in beam 0
word_probs[0, repeat_idx] = 0
# continue pushing around what beam 1 predicts
word_probs[1, repeat_idx + i + 1] = 0
# predict the allowed-repeat again in beam 2
word_probs[2, repeat_idx_ignored] = 0
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i <= ngram_repeat:
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
self.assertFalse(beam.scores[1].eq(self.BLOCKED_SCORE))
self.assertFalse(beam.scores[2].eq(self.BLOCKED_SCORE))
else:
# now beam 0 dies, beam 1 -> beam 0, beam 2 -> beam 1
# and the rest die
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
# since all preds after i=0 are 0, we can check
# that the beam is the correct idx by checking that
# the curr score is the initial score
self.assertTrue(beam.scores[0].eq(-2.3))
self.assertFalse(beam.scores[1].eq(self.BLOCKED_SCORE))
self.assertTrue(beam.scores[1].eq(-5.0))
self.assertTrue(
beam.scores[2:].equal(torch.tensor(
[self.BLOCKED_SCORE] * (beam_sz - 2))))
def test_beam_advance_against_known_reference(self):
scorer = GNMTGlobalScorer(0.7, 0., "avg", "none")
beam = Beam(self.BEAM_SZ, 0, 1, self.EOS_IDX, n_best=self.N_BEST,
exclusion_tokens=set(),
min_length=0,
global_scorer=scorer,
block_ngram_repeat=0)
expected_beam_scores = self.init_step(beam)
expected_beam_scores = self.first_step(beam, expected_beam_scores, 3)
expected_beam_scores = self.second_step(beam, expected_beam_scores, 4)
self.third_step(beam, expected_beam_scores, 5)
def test_beam_advance_against_known_reference(self):
beam = Beam(self.BEAM_SZ, 0, 1, self.EOS_IDX, n_best=self.N_BEST,
exclusion_tokens=set(),
min_length=0,
global_scorer=GlobalScorerStub(),
block_ngram_repeat=0)
expected_beam_scores = self.init_step(beam)
expected_beam_scores = self.first_step(beam, expected_beam_scores, 1)
expected_beam_scores = self.second_step(beam, expected_beam_scores, 1)
self.third_step(beam, expected_beam_scores, 1)
def test_advance_with_some_repeats_gets_blocked(self):
# beam 0 and beam >=2 will repeat (beam >= 2 repeat dummy scores)
beam_sz = 5
n_words = 100
repeat_idx = 47
ngram_repeat = 3
beam = Beam(beam_sz,
0,
1,
2,
n_best=2,
exclusion_tokens=set(),
global_scorer=GlobalScorerStub(),
block_ngram_repeat=ngram_repeat)
for i in range(ngram_repeat + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
# on initial round, only predicted scores for beam 0
# matter. Make two predictions. Top one will be repeated
# in beam zero, second one will live on in beam 1.
word_probs[0, repeat_idx] = -0.1
word_probs[0, repeat_idx + i + 1] = -2.3
else:
# predict the same thing in beam 0
word_probs[0, repeat_idx] = 0
# continue pushing around what beam 1 predicts
word_probs[1, repeat_idx + i + 1] = 0
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i <= ngram_repeat:
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
self.assertFalse(beam.scores[1].eq(self.BLOCKED_SCORE))
else:
# now beam 0 dies (along with the others), beam 1 -> beam 0
self.assertFalse(beam.scores[0].eq(self.BLOCKED_SCORE))
self.assertTrue(beam.scores[1:].equal(
torch.tensor([self.BLOCKED_SCORE] * (beam_sz - 1))))
def test_beam_is_done_when_n_best_beams_eos_using_min_length(self):
# this is also a test that when block_ngram_repeat=0,
# repeating is acceptable
beam_sz = 5
n_words = 100
_non_eos_idxs = [47, 51, 13, 88, 99]
valid_score_dist = torch.log_softmax(torch.tensor(
[6., 5., 4., 3., 2., 1.]),
dim=0)
min_length = 5
eos_idx = 2
beam = Beam(beam_sz,
0,
1,
eos_idx,
n_best=2,
exclusion_tokens=set(),
min_length=min_length,
global_scorer=GlobalScorerStub(),
block_ngram_repeat=0)
for i in range(min_length + 4):
# non-interesting beams are going to get dummy values
word_probs = torch.full((beam_sz, n_words), -float('inf'))
if i == 0:
# "best" prediction is eos - that should be blocked
word_probs[0, eos_idx] = valid_score_dist[0]
# include at least beam_sz predictions OTHER than EOS
# that are greater than -1e20
for j, score in zip(_non_eos_idxs, valid_score_dist[1:]):
word_probs[0, j] = score
elif i <= min_length:
# predict eos in beam 1
word_probs[1, eos_idx] = valid_score_dist[0]
# provide beam_sz other good predictions in other beams
for k, (j, score) in enumerate(
zip(_non_eos_idxs, valid_score_dist[1:])):
beam_idx = min(beam_sz - 1, k)
word_probs[beam_idx, j] = score
else:
word_probs[0, eos_idx] = valid_score_dist[0]
word_probs[1, eos_idx] = valid_score_dist[0]
# provide beam_sz other good predictions in other beams
for k, (j, score) in enumerate(
zip(_non_eos_idxs, valid_score_dist[1:])):
beam_idx = min(beam_sz - 1, k)
word_probs[beam_idx, j] = score
attns = torch.randn(beam_sz)
beam.advance(word_probs, attns)
if i < min_length:
self.assertFalse(beam.done)
elif i == min_length:
# beam 1 dies on min_length
self.assertEqual(beam.finished[0][1], beam.min_length + 1)
self.assertEqual(beam.finished[0][2], 1)
self.assertFalse(beam.done)
else: # i > min_length
# beam 0 dies on the step after beam 1 dies
self.assertEqual(beam.finished[1][1], beam.min_length + 2)
self.assertEqual(beam.finished[1][2], 0)
self.assertTrue(beam.done)
def translate_batch(self, batch):
beam_size = self.beam_size
tgt_field = self.fields['tgt'][0][1]
vocab = tgt_field.vocab
pad = vocab.stoi[tgt_field.pad_token]
eos = vocab.stoi[tgt_field.eos_token]
bos = vocab.stoi[tgt_field.init_token]
b = Beam(beam_size,
n_best=self.n_best,
cuda=self.cuda,
pad=pad,
eos=eos,
bos=bos)
src, src_lengths = batch.src
# why doesn't this contain inflection source lengths when ensembling?
side_info = side_information(batch)
encoder_out = self.model.encode(src, lengths=src_lengths, **side_info)
enc_states = encoder_out["enc_state"]
memory_bank = encoder_out["memory_bank"]
infl_memory_bank = encoder_out.get("inflection_memory_bank", None)
self.model.init_decoder_state(enc_states)
results = dict()
if "tgt" in batch.__dict__:
results["gold_score"] = self._score_target(
batch,
memory_bank,
src_lengths,
inflection_memory_bank=infl_memory_bank,
**side_info)
self.model.init_decoder_state(enc_states)
else:
results["gold_score"] = 0
# (2) Repeat src objects `beam_size` times.
self.model.map_decoder_state(
lambda state, dim: tile(state, beam_size, dim=dim))
if isinstance(memory_bank, tuple):
memory_bank = tuple(tile(x, beam_size, dim=1) for x in memory_bank)
else:
memory_bank = tile(memory_bank, beam_size, dim=1)
memory_lengths = tile(src_lengths, beam_size)
if infl_memory_bank is not None:
if isinstance(infl_memory_bank, tuple):
infl_memory_bank = tuple(
tile(x, beam_size, dim=1) for x in infl_memory_bank)
else:
infl_memory_bank = tile(infl_memory_bank, beam_size, dim=1)
tiled_infl_len = tile(side_info["inflection_lengths"], beam_size)
side_info["inflection_lengths"] = tiled_infl_len
if "language" in side_info:
side_info["language"] = tile(side_info["language"], beam_size)
for i in range(self.max_length):
if b.done():
break
inp = b.current_state.unsqueeze(0)
# the decoder expects an input of tgt_len x batch
dec_out, dec_attn = self.model.decode(
inp,
memory_bank,
memory_lengths=memory_lengths,
inflection_memory_bank=infl_memory_bank,
**side_info)
attn = dec_attn["lemma"].squeeze(0)
out = self.model.generator(dec_out.squeeze(0),
transform=True,
**side_info)
# b.advance will take attn (beam size x src length)
b.advance(out, dec_attn)
select_indices = b.current_origin
self.model.map_decoder_state(
lambda state, dim: state.index_select(dim, select_indices))
scores, ks = b.sort_finished()
hyps, attn, out_probs = [], [], []
for i, (times, k) in enumerate(ks[:self.n_best]):
hyp, att, out_p = b.get_hyp(times, k)
hyps.append(hyp)
attn.append(att)
out_probs.append(out_p)
results["preds"] = hyps
results["scores"] = scores
results["attn"] = attn
if self.beam_accum is not None:
parent_ids = [t.tolist() for t in b.prev_ks]
self.beam_accum["beam_parent_ids"].append(parent_ids)
scores = [["%4f" % s for s in t.tolist()]
for t in b.all_scores][1:]
self.beam_accum["scores"].append(scores)
pred_ids = [[vocab.itos[i] for i in t.tolist()]
for t in b.next_ys][1:]
self.beam_accum["predicted_ids"].append(pred_ids)
if self.attn_path is not None:
save_attn = {k: v.cpu() for k, v in attn[0].items()}
src_seq = self.itos(src, "src")
pred_seq = self.itos(hyps[0], "tgt")
attn_dict = {"src": src_seq, "pred": pred_seq, "attn": save_attn}
if "inflection" in save_attn:
inflection_seq = self.itos(batch.inflection[0], "inflection")
attn_dict["inflection"] = inflection_seq
self.attns.append(attn_dict)
if self.probs_path is not None:
save_probs = out_probs[0].cpu()
self.probs.append(save_probs)
return results
def _translate_batch(self, batch, data):
# (0) Prep each of the components of the search.
# And helper method for reducing verbosity.
beam_size = self.beam_size
batch_size = batch.batch_size
data_type = data.data_type
vocab = self.fields["tgt"].vocab
# Define a list of tokens to exclude from ngram-blocking
# exclusion_list = ["<t>", "</t>", "."]
exclusion_tokens = set(
[vocab.stoi[t] for t in self.ignore_when_blocking])
beam_batch = [
Beam(
beam_size,
n_best=self.n_best,
cuda=self.cuda,
global_scorer=self.global_scorer,
pad=vocab.stoi[inputters.PAD_WORD],
eos=vocab.stoi[inputters.EOS_WORD],
bos=vocab.stoi[inputters.BOS_WORD],
min_length=self.min_length,
stepwise_penalty=self.stepwise_penalty,
block_ngram_repeat=self.block_ngram_repeat,
exclusion_tokens=exclusion_tokens,
) for __ in range(batch_size)
]
# (1) Run the encoder on the src.
src, enc_states, memory_bank, src_lengths = self._run_encoder(
batch, data_type)
self.model.decoder.init_state(src, memory_bank, enc_states)
results = {}
results["predictions"] = []
results["scores"] = []
results["attention"] = []
results["batch"] = batch
if "tgt" in batch.__dict__:
results["gold_score"] = self._score_target(
batch,
memory_bank,
src_lengths,
data,
batch.src_map
if data_type == "text" and self.copy_attn else None,
)
self.model.decoder.init_state(src, memory_bank, enc_states)
else:
results["gold_score"] = [0] * batch_size
# (2) Repeat src objects `beam_size` times.
# We use now batch_size x beam_size (same as fast mode)
src_map = (tile(batch.src_map, beam_size, dim=1)
if data.data_type == "text" and self.copy_attn else None)
self.model.decoder.map_state(
lambda state, dim: tile(state, beam_size, dim=dim))
if isinstance(memory_bank, tuple):
memory_bank = tuple(tile(x, beam_size, dim=1) for x in memory_bank)
else:
memory_bank = tile(memory_bank, beam_size, dim=1)
memory_lengths = tile(src_lengths, beam_size)
# (3) run the decoder to generate sentences, using beam search.
for i in range(self.max_length):
if all((b.done() for b in beam_batch)):
break
# (a) Construct batch x beam_size nxt words.
# Get all the pending current beam words and arrange for forward.
inp = torch.stack([b.current_state for b in beam_batch])
inp = inp.view(1, -1, 1)
# (b) Decode and forward
out, beam_attn = self._decode_and_generate(
inp,
memory_bank,
batch,
data,
memory_lengths=memory_lengths,
src_map=src_map,
step=i,
)
out = out.view(batch_size, beam_size, -1)
beam_attn = beam_attn.view(batch_size, beam_size, -1)
# (c) Advance each beam.
select_indices_array = []
# Loop over the batch_size number of beam
for j, b in enumerate(beam_batch):
b.advance(out[j, :], beam_attn[j, :, :memory_lengths[j]])
select_indices_array.append(b.current_origin + j * beam_size)
select_indices = torch.cat(select_indices_array)
self.model.decoder.map_state(
lambda state, dim: state.index_select(dim, select_indices))
# (4) Extract sentences from beam.
for b in beam_batch:
n_best = self.n_best
scores, ks = b.sort_finished(minimum=n_best)
hyps, attn = [], []
for i, (times, k) in enumerate(ks[:n_best]):
hyp, att = b.get_hyp(times, k)
hyps.append(hyp)
attn.append(att)
results["predictions"].append(hyps)
results["scores"].append(scores)
results["attention"].append(attn)
if self.beam_accum is not None:
parent_ids = [t.tolist() for t in b.prev_ks]
self.beam_accum["beam_parent_ids"].append(parent_ids)
scores = [["%4f" % s for s in t.tolist()]
for t in b.all_scores][1:]
self.beam_accum["scores"].append(scores)
pred_ids = [[vocab.itos[i] for i in t.tolist()]
for t in b.next_ys][1:]
self.beam_accum["predicted_ids"].append(pred_ids)
if self.beam_scores is not None:
self.beam_scores.append(torch.stack(b.all_scores).cpu())
return results
def generate(self, src, lengths, dec_idx, max_length=20, beam_size=5, n_best=1):
assert dec_idx == 0 or dec_idx == 1
batch_size = src.size(1)
def var(a):
return torch.tensor(a, requires_grad=False)
def rvar(a):
return var(a.repeat(1, beam_size, 1))
def bottle(m):
return m.view(batch_size * beam_size, -1)
def unbottle(m):
return m.view(beam_size, batch_size, -1)
def from_beam(beam):
ret = {"predictions": [],
"scores": [],
"attention": []}
for b in beam:
scores, ks = b.sort_finished(minimum=n_best)
hyps, attn = [], []
for i, (times, k) in enumerate(ks[:n_best]):
hyp, att = b.get_hyp(times, k)
hyps.append(hyp)
attn.append(att)
ret["predictions"].append(hyps)
ret["scores"].append(scores)
ret["attention"].append(attn)
return ret
scorer = GNMTGlobalScorer(0, 0, "none", "none")
beam = [Beam(beam_size, n_best=n_best,
cuda=self.cuda(),
global_scorer=scorer,
pad=PAD_IDX,
eos=SOS_IDX,
bos=EOS_IDX,
min_length=0,
stepwise_penalty=False,
block_ngram_repeat=0)
for __ in range(batch_size)]
enc_final, memory_bank = self.encoder(src, lengths)
token = torch.full((1, batch_size, 1), SOS_IDX, dtype=torch.long, device=next(self.parameters()).device)
dec_state = enc_final
dec_state = self.choose_decoder(dec_idx).init_decoder_state(src, memory_bank, dec_state)
memory_bank = rvar(memory_bank.data)
memory_lengths = lengths.repeat(beam_size)
dec_state.repeat_beam_size_times(beam_size)
# unroll
all_indices = []
for i in range(max_length):
if all((b.done() for b in beam)):
break
inp = var(torch.stack([b.get_current_state() for b in beam]).t().contiguous().view(1, -1))
inp = inp.unsqueeze(2)
decoder_output, dec_state, attn = self.choose_decoder(dec_idx)(inp, memory_bank, dec_state, memory_lengths=memory_lengths, step=i)
decoder_output = decoder_output.squeeze(0)
out = self.generator(decoder_output).data
out = unbottle(out)
# beam x tgt_vocab
beam_attn = unbottle(attn["std"])
for j, b in enumerate(beam):
b.advance(out[:, j], beam_attn.data[:, j, :memory_lengths[j]])
dec_state.beam_update(j, b.get_current_origin(), beam_size)
ret = from_beam(beam)
# ret["src"] = src.transpose(1, 0)
return ret
