Spaces:
Runtime error
Runtime error
File size: 9,289 Bytes
6a62ffb |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 |
# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
import math
import torch
import torch.nn.functional as F
from fairseq.models.nat import (
_apply_del_words,
_apply_ins_masks,
_apply_ins_words,
_fill,
_skip,
_skip_encoder_out,
)
class _EnsembleModelEncoder(object):
def __init__(self, models):
self.models = models
def reorder_encoder_out(self, encoder_outs, new_order):
encoder_outs = [
model.encoder.reorder_encoder_out(encoder_out, new_order)
for model, encoder_out in zip(self.models, encoder_outs)
]
return encoder_outs
class BasicEnsembleModel(torch.nn.Module):
"""A wrapper around an ensemble of models."""
def __init__(self, models):
super().__init__()
self.models = torch.nn.ModuleList(models)
self.bos = self.models[0].decoder.dictionary.bos()
self.eos = self.models[0].decoder.dictionary.eos()
self.pad = self.models[0].decoder.dictionary.pad()
self.unk = self.models[0].decoder.dictionary.unk()
self.encoder = _EnsembleModelEncoder(self.models)
def has_encoder(self):
return hasattr(self.models[0], "encoder")
def max_decoder_positions(self):
return min(m.max_decoder_positions() for m in self.models)
@torch.no_grad()
def forward_encoder(self, encoder_input):
if not self.has_encoder():
return None
return [model.forward_encoder(encoder_input) for model in self.models]
@torch.no_grad()
def forward_decoder(self, *inputs):
raise NotImplementedError
def initialize_output_tokens(self, *inputs):
raise NotImplementedError
class EnsembleLevT(BasicEnsembleModel):
"""A wrapper around an ensemble of models."""
def __init__(self, models):
super().__init__(models)
@torch.no_grad()
def forward_decoder(
self, decoder_out, encoder_outs, eos_penalty=0.0, max_ratio=None, **kwargs
):
# LevT ensembling
# A pipeline of three steps: deletion, placeholder, and word insertion.
# We need to average scores in each step in a pipeline way because of dependence.
# deletion
output_tokens = decoder_out.output_tokens
output_scores = decoder_out.output_scores
attn = decoder_out.attn
bsz = output_tokens.size(0)
if max_ratio is None:
max_lens = output_tokens.new().fill_(255)
else:
if not encoder_outs[0]["encoder_padding_mask"]:
src_lens = (
encoder_outs[0]["encoder_out"][0]
.new(bsz)
.fill_(encoder_outs[0]["encoder_out"][0].size(1))
)
else:
src_lens = (~encoder_outs[0]["encoder_padding_mask"][0]).sum(1)
max_lens = (src_lens * max_ratio).clamp(min=10).long()
# delete words
# do not delete tokens if it is <s> </s>
can_del_word = output_tokens.ne(self.pad).sum(1) > 2
if can_del_word.sum() != 0: # we cannot delete, skip
output_tokens, output_scores, attn = self.forward_word_del(
encoder_outs,
output_tokens,
output_scores,
attn,
can_del_word,
)
# insert placeholders
can_ins_mask = output_tokens.ne(self.pad).sum(1) < max_lens
if can_ins_mask.sum() != 0:
output_tokens, output_scores = self.forward_mask_ins(
encoder_outs,
output_tokens,
output_scores,
can_ins_mask,
eos_penalty,
max_lens,
)
# insert words
can_ins_word = output_tokens.eq(self.unk).sum(1) > 0
if can_ins_word.sum() != 0:
output_tokens, output_scores, attn = self.forward_word_ins(
encoder_outs,
output_tokens,
output_scores,
attn,
can_ins_word,
)
# delete some unnecessary paddings
cut_off = output_tokens.ne(self.pad).sum(1).max()
output_tokens = output_tokens[:, :cut_off]
output_scores = output_scores[:, :cut_off]
attn = None if attn is None else attn[:, :cut_off, :]
return decoder_out._replace(
output_tokens=output_tokens,
output_scores=output_scores,
attn=attn,
history=None,
)
def forward_word_del(
self, encoder_outs, output_tokens, output_scores, attn, can_del_word
):
word_del_score_avg = []
word_del_attn_avg = []
for model, encoder_out in zip(self.models, encoder_outs):
word_del_out, word_del_attn = model.decoder.forward_word_del(
_skip(output_tokens, can_del_word),
_skip_encoder_out(model.encoder, encoder_out, can_del_word),
)
word_del_score = F.log_softmax(word_del_out, 2)
word_del_score_avg.append(word_del_score)
word_del_attn_avg.append(word_del_attn)
word_del_score_avg = torch.logsumexp(
torch.stack(word_del_score_avg, dim=0), dim=0
) - math.log(len(self.models))
word_del_pred = word_del_score_avg.max(-1)[1].bool()
if word_del_attn_avg[0] is not None:
word_del_attn_avg = torch.stack(word_del_attn_avg, dim=0) / len(self.models)
else:
word_del_attn_avg = None
_tokens, _scores, _attn = _apply_del_words(
output_tokens[can_del_word],
output_scores[can_del_word],
word_del_attn_avg,
word_del_pred,
self.pad,
self.bos,
self.eos,
)
output_tokens = _fill(output_tokens, can_del_word, _tokens, self.pad)
output_scores = _fill(output_scores, can_del_word, _scores, 0)
attn = _fill(attn, can_del_word, _attn, 0.0)
return output_tokens, output_scores, attn
def forward_mask_ins(
self,
encoder_outs,
output_tokens,
output_scores,
can_ins_mask,
eos_penalty,
max_lens,
):
mask_ins_score_avg = []
for model, encoder_out in zip(self.models, encoder_outs):
mask_ins_out, _ = model.decoder.forward_mask_ins(
_skip(output_tokens, can_ins_mask),
_skip_encoder_out(model.encoder, encoder_out, can_ins_mask),
)
mask_ins_score = F.log_softmax(mask_ins_out, 2)
if eos_penalty > 0.0:
mask_ins_score[:, :, 0] -= eos_penalty
mask_ins_score_avg.append(mask_ins_score)
mask_ins_score_avg = torch.logsumexp(
torch.stack(mask_ins_score_avg, dim=0), dim=0
) - math.log(len(self.models))
mask_ins_pred = mask_ins_score_avg.max(-1)[1]
mask_ins_pred = torch.min(
mask_ins_pred, max_lens[can_ins_mask, None].expand_as(mask_ins_pred)
)
_tokens, _scores = _apply_ins_masks(
output_tokens[can_ins_mask],
output_scores[can_ins_mask],
mask_ins_pred,
self.pad,
self.unk,
self.eos,
)
output_tokens = _fill(output_tokens, can_ins_mask, _tokens, self.pad)
output_scores = _fill(output_scores, can_ins_mask, _scores, 0)
return output_tokens, output_scores
def forward_word_ins(
self, encoder_outs, output_tokens, output_scores, attn, can_ins_word
):
word_ins_score_avg = []
word_ins_attn_avg = []
for model, encoder_out in zip(self.models, encoder_outs):
word_ins_out, word_ins_attn = model.decoder.forward_word_ins(
_skip(output_tokens, can_ins_word),
_skip_encoder_out(model.encoder, encoder_out, can_ins_word),
)
word_ins_score = F.log_softmax(word_ins_out, 2)
word_ins_score_avg.append(word_ins_score)
word_ins_attn_avg.append(word_ins_attn)
word_ins_score_avg = torch.logsumexp(
torch.stack(word_ins_score_avg, dim=0), dim=0
) - math.log(len(self.models))
if word_ins_attn_avg[0] is not None:
word_ins_attn_avg = torch.stack(word_ins_attn_avg, dim=0) / len(self.models)
else:
word_ins_attn_avg = None
word_ins_score_max, word_ins_pred = word_ins_score_avg.max(-1)
_tokens, _scores = _apply_ins_words(
output_tokens[can_ins_word],
output_scores[can_ins_word],
word_ins_pred,
word_ins_score_max,
self.unk,
)
output_tokens = _fill(output_tokens, can_ins_word, _tokens, self.pad)
output_scores = _fill(output_scores, can_ins_word, _scores, 0)
attn = _fill(attn, can_ins_word, word_ins_attn, 0.0)
return output_tokens, output_scores, attn
def initialize_output_tokens(self, encoder_outs, src_tokens):
# LevT doesn't do length prediction.
return self.models[0].initialize_output_tokens(encoder_outs[0], src_tokens)
|