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# 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 logging | |
import os | |
from dataclasses import dataclass, field | |
from typing import Optional | |
import numpy as np | |
from omegaconf import II | |
from fairseq.data import ( | |
AppendTokenDataset, | |
ConcatDataset, | |
DenoisingDataset, | |
Dictionary, | |
PrependTokenDataset, | |
ResamplingDataset, | |
SortDataset, | |
TokenBlockDataset, | |
data_utils, | |
) | |
from fairseq.data.encoders.utils import get_whole_word_mask | |
from fairseq.tasks import register_task | |
from .denoising import DenoisingConfig, DenoisingTask | |
logger = logging.getLogger(__name__) | |
class MultilingualDenoisingConfig(DenoisingConfig): | |
multilang_sampling_alpha: float = field( | |
default=1.0, | |
metadata={"help": "smoothing alpha for sample ratios across multiple datasets"}, | |
) | |
add_lang_token: bool = field( | |
default=False, | |
metadata={"help": ""}, | |
) | |
langs: Optional[str] = field( | |
default=None, | |
metadata={"help": "language ids we are considering"}, | |
) | |
no_whole_word_mask_langs: str = field( | |
default="", | |
metadata={ | |
"help": "languages without spacing between words don't support whole word masking" | |
}, | |
) | |
train_subset: str = II("common.train_subset") | |
valid_subset: str = II("common.valid_subset") | |
class MultilingualDenoisingTask(DenoisingTask): | |
cfg: MultilingualDenoisingConfig | |
def setup_task(cls, cfg: MultilingualDenoisingConfig, **kwargs): | |
"""Setup the task.""" | |
paths = cfg.data.split(":") | |
assert len(paths) > 0 | |
dictionary = Dictionary.load(os.path.join(paths[0], "dict.txt")) | |
data_path = paths[0] | |
if cfg.langs is None: | |
languages = sorted( | |
[ | |
name | |
for name in os.listdir(data_path) | |
if os.path.isdir(os.path.join(data_path, name)) | |
] | |
) | |
else: | |
languages = cfg.langs.split(",") | |
if cfg.add_lang_token: | |
for lang in languages: | |
dictionary.add_symbol("[{}]".format(lang)) | |
logger.info("dictionary: {} types".format(len(dictionary))) | |
if not hasattr(cfg, "shuffle_instance"): | |
cfg.shuffle_instance = False | |
return cls(cfg, dictionary) | |
def __init__(self, cfg: MultilingualDenoisingConfig, dictionary): | |
super().__init__(cfg, dictionary) | |
self.dictionary = dictionary | |
# add mask token | |
self.mask_idx = self.dictionary.add_symbol("<mask>") | |
self.cfg = cfg | |
def _get_sample_prob(self, dataset_lens): | |
""" | |
Get smoothed sampling probability by languages. This helps low resource | |
languages by upsampling them. | |
""" | |
prob = dataset_lens / dataset_lens.sum() | |
smoothed_prob = prob**self.cfg.multilang_sampling_alpha | |
smoothed_prob = smoothed_prob / smoothed_prob.sum() | |
return smoothed_prob | |
def load_dataset(self, split, epoch=1, combine=False, **kwargs): | |
"""Load a given dataset split. | |
Args: | |
split (str): name of the split (e.g., train, valid, test) | |
""" | |
paths = self.cfg.data.split(":") | |
assert len(paths) > 0 | |
data_path = paths[(epoch - 1) % len(paths)] | |
split_path = os.path.join(data_path, split) | |
if self.cfg.langs is None: | |
languages = sorted( | |
[ | |
name | |
for name in os.listdir(data_path) | |
if os.path.isdir(os.path.join(data_path, name)) | |
] | |
) | |
else: | |
languages = self.cfg.langs.split(",") | |
for name in languages: | |
p = os.path.join(data_path, name) | |
assert os.path.exists(p), "data not found: {}".format(p) | |
logger.info("Training on {0} languages: {1}".format(len(languages), languages)) | |
logger.info( | |
"Language to id mapping: ", {lang: id for id, lang in enumerate(languages)} | |
) | |
mask_whole_words = get_whole_word_mask(self.cfg.bpe, self.dictionary) | |
language_without_segmentations = self.cfg.no_whole_word_mask_langs.split(",") | |
lang_datasets = [] | |
for language in languages: | |
split_path = os.path.join(data_path, language, split) | |
dataset = data_utils.load_indexed_dataset( | |
split_path, | |
self.source_dictionary, | |
self.cfg.dataset_impl, | |
combine=combine, | |
) | |
if dataset is None: | |
raise FileNotFoundError( | |
"Dataset not found: {} ({})".format(split, split_path) | |
) | |
end_token = ( | |
self.source_dictionary.index("[{}]".format(language)) | |
if self.cfg.add_lang_token | |
else self.source_dictionary.eos() | |
) | |
# create continuous blocks of tokens | |
dataset = TokenBlockDataset( | |
dataset, | |
dataset.sizes, | |
self.cfg.tokens_per_sample - 2, # one less for <s> | |
pad=self.source_dictionary.pad(), | |
eos=end_token, | |
break_mode=self.cfg.sample_break_mode, | |
) | |
logger.info("loaded {} blocks from: {}".format(len(dataset), split_path)) | |
# prepend beginning-of-sentence token (<s>, equiv. to [CLS] in BERT) | |
dataset = PrependTokenDataset(dataset, self.source_dictionary.bos()) | |
dataset = AppendTokenDataset(dataset, end_token) | |
lang_mask_whole_words = ( | |
mask_whole_words | |
if language not in language_without_segmentations | |
else None | |
) | |
lang_dataset = DenoisingDataset( | |
dataset, | |
dataset.sizes, | |
self.dictionary, | |
self.mask_idx, | |
lang_mask_whole_words, | |
shuffle=self.cfg.shuffle_instance, | |
seed=self.cfg.seed, | |
mask=self.cfg.mask, | |
mask_random=self.cfg.mask_random, | |
insert=self.cfg.insert, | |
rotate=self.cfg.rotate, | |
permute_sentences=self.cfg.permute_sentences, | |
bpe=self.cfg.bpe, | |
replace_length=self.cfg.replace_length, | |
mask_length=self.cfg.mask_length, | |
poisson_lambda=self.cfg.poisson_lambda, | |
eos=None | |
if not self.cfg.add_lang_token | |
else self.source_dictionary.index("[{}]".format(language)), | |
) | |
lang_datasets.append(lang_dataset) | |
dataset_lengths = np.array( | |
[len(d) for d in lang_datasets], | |
dtype=float, | |
) | |
logger.info( | |
"loaded total {} blocks for all languages".format( | |
int(dataset_lengths.sum()), | |
) | |
) | |
if split == self.cfg.train_subset: | |
# For train subset, additionally up or down sample languages. | |
sample_probs = self._get_sample_prob(dataset_lengths) | |
logger.info( | |
"Sample probability by language: {}".format( | |
{ | |
lang: "{0:.4f}".format(sample_probs[id]) | |
for id, lang in enumerate(languages) | |
} | |
) | |
) | |
size_ratio = (sample_probs * dataset_lengths.sum()) / dataset_lengths | |
logger.info( | |
"Up/Down Sampling ratio by language: {}".format( | |
{ | |
lang: "{0:.2f}".format(size_ratio[id]) | |
for id, lang in enumerate(languages) | |
} | |
) | |
) | |
resampled_lang_datasets = [ | |
ResamplingDataset( | |
lang_datasets[i], | |
size_ratio=size_ratio[i], | |
seed=self.cfg.seed, | |
epoch=epoch, | |
replace=size_ratio[i] >= 1.0, | |
) | |
for i, d in enumerate(lang_datasets) | |
] | |
dataset = ConcatDataset( | |
resampled_lang_datasets, | |
) | |
else: | |
dataset = ConcatDataset(lang_datasets) | |
lang_splits = [split] | |
for lang_id, lang_dataset in enumerate(lang_datasets): | |
split_name = split + "_" + languages[lang_id] | |
lang_splits.append(split_name) | |
self.datasets[split_name] = lang_dataset | |
if split in self.cfg.valid_subset: | |
self.cfg.valid_subset = self.cfg.valid_subset.replace( | |
split, ",".join(lang_splits) | |
) | |
with data_utils.numpy_seed(self.cfg.seed + epoch): | |
shuffle = np.random.permutation(len(dataset)) | |
self.datasets[split] = SortDataset( | |
dataset, | |
sort_order=[ | |
shuffle, | |
dataset.sizes, | |
], | |
) | |