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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 | |
| import numpy as np | |
| 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 DenoisingTask | |
| logger = logging.getLogger(__name__) | |
| class MultilingualDenoisingTask(DenoisingTask): | |
| def add_args(parser): | |
| DenoisingTask.add_args(parser) | |
| parser.add_argument( | |
| "--multilang-sampling-alpha", | |
| type=float, | |
| default=1.0, | |
| help="smoothing alpha for sample ratios across multiple datasets", | |
| ) | |
| parser.add_argument("--add-lang-token", default=False, action="store_true") | |
| parser.add_argument( | |
| "--langs", type=str, help="language ids we are considering", default=None | |
| ) | |
| parser.add_argument( | |
| "--no-whole-word-mask-langs", | |
| type=str, | |
| default="", | |
| metavar="N", | |
| help="languages without spacing between words dont support whole word masking", | |
| ) | |
| def setup_task(cls, args, **kwargs): | |
| """Setup the task.""" | |
| paths = args.data.split(":") | |
| assert len(paths) > 0 | |
| dictionary = Dictionary.load(os.path.join(paths[0], "dict.txt")) | |
| data_path = paths[0] | |
| if args.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 = args.langs.split(",") | |
| if args.add_lang_token: | |
| for lang in languages: | |
| dictionary.add_symbol("[{}]".format(lang)) | |
| logger.info("dictionary: {} types".format(len(dictionary))) | |
| if not hasattr(args, "shuffle_instance"): | |
| args.shuffle_instance = False | |
| return cls(args, dictionary) | |
| def __init__(self, args, dictionary): | |
| super().__init__(args, dictionary) | |
| self.dictionary = dictionary | |
| self.seed = args.seed | |
| # add mask token | |
| self.mask_idx = self.dictionary.add_symbol("<mask>") | |
| self.langs = args.langs | |
| self.args = args | |
| def _get_sample_prob(self, dataset_lens): | |
| """ | |
| Get smoothed sampling porbability by languages. This helps low resource | |
| languages by upsampling them. | |
| """ | |
| prob = dataset_lens / dataset_lens.sum() | |
| smoothed_prob = prob ** self.args.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.args.data.split(":") | |
| assert len(paths) > 0 | |
| data_path = paths[(epoch - 1) % len(paths)] | |
| split_path = os.path.join(data_path, split) | |
| if self.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.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.args, self.dictionary) | |
| language_without_segmentations = self.args.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.args.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.args.add_lang_token | |
| else self.source_dictionary.eos() | |
| ) | |
| # create continuous blocks of tokens | |
| dataset = TokenBlockDataset( | |
| dataset, | |
| dataset.sizes, | |
| self.args.tokens_per_sample - 2, # one less for <s> | |
| pad=self.source_dictionary.pad(), | |
| eos=end_token, | |
| break_mode=self.args.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.args.shuffle_instance, | |
| seed=self.seed, | |
| args=self.args, | |
| eos=None | |
| if not self.args.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.args.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.args.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.args.valid_subset: | |
| self.args.valid_subset = self.args.valid_subset.replace( | |
| split, ",".join(lang_splits) | |
| ) | |
| with data_utils.numpy_seed(self.args.seed + epoch): | |
| shuffle = np.random.permutation(len(dataset)) | |
| self.datasets[split] = SortDataset( | |
| dataset, | |
| sort_order=[ | |
| shuffle, | |
| dataset.sizes, | |
| ], | |
| ) | |