275 lines
8.6 KiB
Python
275 lines
8.6 KiB
Python
# Copyright (c) Facebook, Inc. and its affiliates.
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#
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# This source code is licensed under the MIT license found in the
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# LICENSE file in the root directory of this source tree.
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import logging
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import os
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from fairseq import utils
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from fairseq.data import (
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AppendTokenDataset,
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DenoisingDataset,
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Dictionary,
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IdDataset,
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NestedDictionaryDataset,
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NumelDataset,
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PadDataset,
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PrependTokenDataset,
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StripTokenDataset,
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TokenBlockDataset,
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data_utils,
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)
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from fairseq.data.encoders.utils import get_whole_word_mask
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from fairseq.data.shorten_dataset import maybe_shorten_dataset
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from fairseq.tasks import LegacyFairseqTask, register_task
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import numpy as np
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logger = logging.getLogger(__name__)
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@register_task("denoising")
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class DenoisingTask(LegacyFairseqTask):
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"""
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Denoising task for applying sequence to sequence denoising. (ie. BART)
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"""
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@staticmethod
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def add_args(parser):
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"""Add task-specific arguments to the parser."""
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parser.add_argument("data", help="path to data directory")
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parser.add_argument(
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"--tokens-per-sample",
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default=512,
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type=int,
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help="max number of total tokens over all segments"
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" per sample for dataset",
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)
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parser.add_argument(
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"--sample-break-mode",
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default="complete_doc",
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type=str,
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help="mode for breaking sentence",
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)
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parser.add_argument(
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"--mask",
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default=0.0,
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type=float,
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help="fraction of words/subwords that will be masked",
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)
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parser.add_argument(
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"--mask-random",
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default=0.0,
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type=float,
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help="instead of using [MASK], use random token this often",
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)
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parser.add_argument(
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"--insert",
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default=0.0,
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type=float,
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help="insert this percentage of additional random tokens",
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)
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parser.add_argument(
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"--permute",
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default=0.0,
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type=float,
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help="take this proportion of subwords and permute them",
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)
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parser.add_argument(
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"--rotate",
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default=0.5,
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type=float,
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help="rotate this proportion of inputs",
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)
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parser.add_argument(
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"--poisson-lambda",
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default=3.0,
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type=float,
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help="randomly shuffle sentences for this proportion of inputs",
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)
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parser.add_argument(
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"--permute-sentences",
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default=0.0,
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type=float,
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help="shuffle this proportion of sentences in all inputs",
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)
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parser.add_argument(
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"--mask-length",
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default="subword",
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type=str,
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choices=["subword", "word", "span-poisson"],
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help="mask length to choose",
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)
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parser.add_argument(
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"--replace-length",
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default=-1,
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type=int,
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help="when masking N tokens, replace with 0, 1, or N tokens (use -1 for N)",
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)
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parser.add_argument(
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"--max-source-positions",
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default=1024,
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type=int,
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metavar="N",
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help="max number of tokens in the source sequence",
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)
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parser.add_argument(
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"--max-target-positions",
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default=1024,
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type=int,
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metavar="N",
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help="max number of tokens in the target sequence",
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)
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parser.add_argument(
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"--shorten-method",
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default="none",
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choices=["none", "truncate", "random_crop"],
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help="if not none, shorten sequences that exceed --tokens-per-sample",
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)
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parser.add_argument(
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"--shorten-data-split-list",
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default="",
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help="comma-separated list of dataset splits to apply shortening to, "
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'e.g., "train,valid" (default: all dataset splits)',
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)
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def __init__(self, args, dictionary):
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super().__init__(args)
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self.dictionary = dictionary
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self.seed = args.seed
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# add mask token
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self.mask_idx = self.dictionary.add_symbol("<mask>")
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@classmethod
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def setup_task(cls, args, **kwargs):
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"""Setup the task."""
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dictionary = Dictionary.load(os.path.join(args.data, "dict.txt"))
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logger.info("dictionary: {} types".format(len(dictionary)))
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if not hasattr(args, "shuffle_instance"):
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args.shuffle_instance = False
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return cls(args, dictionary)
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def load_dataset(self, split, epoch=1, combine=False, **kwargs):
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"""Load a given dataset split.
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Args:
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split (str): name of the split (e.g., train, valid, test)
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"""
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paths = utils.split_paths(self.args.data)
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assert len(paths) > 0
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data_path = paths[(epoch - 1) % len(paths)]
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split_path = os.path.join(data_path, split)
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dataset = data_utils.load_indexed_dataset(
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split_path,
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self.dictionary,
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self.args.dataset_impl,
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combine=combine,
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)
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if dataset is None:
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raise FileNotFoundError(
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"Dataset not found: {} ({})".format(split, split_path)
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)
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dataset = StripTokenDataset(dataset, self.dictionary.eos())
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dataset = maybe_shorten_dataset(
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dataset,
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split,
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self.args.shorten_data_split_list,
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self.args.shorten_method,
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self.args.tokens_per_sample,
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self.args.seed,
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)
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# create continuous blocks of tokens
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dataset = TokenBlockDataset(
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dataset,
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dataset.sizes,
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self.args.tokens_per_sample - 2, # one less for <s> and one for </s>
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pad=self.dictionary.pad(),
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eos=self.dictionary.eos(),
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break_mode=self.args.sample_break_mode,
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document_sep_len=0,
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)
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# prepend beginning-of-sentence token (<s>, equiv. to [CLS] in BERT)
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dataset = PrependTokenDataset(dataset, self.source_dictionary.bos())
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dataset = AppendTokenDataset(dataset, self.source_dictionary.eos())
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mask_whole_words = (
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get_whole_word_mask(self.args, self.source_dictionary)
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if self.args.mask_length != "subword"
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else None
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)
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self.datasets[split] = DenoisingDataset(
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dataset,
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dataset.sizes,
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self.dictionary,
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self.mask_idx,
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mask_whole_words,
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shuffle=self.args.shuffle_instance,
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seed=self.seed,
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args=self.args,
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)
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logger.info(
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"Split: {0}, Loaded {1} samples of denoising_dataset".format(
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split,
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len(self.datasets[split]),
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)
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)
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def build_dataset_for_inference(self, src_tokens, src_lengths, **kwargs):
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"""
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Generate batches for inference. We assume that the input begins with a
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bos symbol (`<s>`) and ends with an eos symbol (`</s>`).
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"""
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pad = self.source_dictionary.pad()
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eos = self.source_dictionary.eos()
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src_dataset = TokenBlockDataset(
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src_tokens,
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src_lengths,
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block_size=self.args.tokens_per_sample - 2, # for <s> and </s>
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pad=pad,
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eos=eos,
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break_mode=self.args.sample_break_mode,
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document_sep_len=0,
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)
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prev_output_tokens = PrependTokenDataset(
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StripTokenDataset(src_dataset, eos), eos
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)
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src_dataset = PadDataset(src_dataset, pad_idx=pad, left_pad=False)
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return NestedDictionaryDataset(
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{
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"id": IdDataset(),
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"net_input": {
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"src_tokens": src_dataset,
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"src_lengths": NumelDataset(src_dataset, reduce=False),
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"prev_output_tokens": PadDataset(
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prev_output_tokens, pad_idx=pad, left_pad=False
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),
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},
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"target": src_dataset,
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},
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sizes=[np.array(src_lengths)],
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)
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def max_positions(self):
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"""Return the max sentence length allowed by the task."""
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return (self.args.max_source_positions, self.args.max_target_positions)
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@property
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def source_dictionary(self):
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"""Return the source :class:`~fairseq.data.Dictionary`."""
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return self.dictionary
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@property
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def target_dictionary(self):
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"""Return the target :class:`~fairseq.data.Dictionary`."""
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return self.dictionary
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