mirror of
https://github.com/SillyTavern/SillyTavern-Extras.git
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478 lines
19 KiB
Python
478 lines
19 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 numpy as np
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import torch
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from fairseq.data import FairseqDataset, data_utils
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logger = logging.getLogger(__name__)
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def collate(
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samples,
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pad_idx,
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eos_idx,
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left_pad_source=True,
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left_pad_target=False,
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input_feeding=True,
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pad_to_length=None,
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pad_to_multiple=1,
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):
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if len(samples) == 0:
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return {}
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def merge(key, left_pad, move_eos_to_beginning=False, pad_to_length=None):
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return data_utils.collate_tokens(
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[s[key] for s in samples],
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pad_idx,
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eos_idx,
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left_pad,
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move_eos_to_beginning,
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pad_to_length=pad_to_length,
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pad_to_multiple=pad_to_multiple,
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)
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def check_alignment(alignment, src_len, tgt_len):
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if alignment is None or len(alignment) == 0:
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return False
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if (
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alignment[:, 0].max().item() >= src_len - 1
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or alignment[:, 1].max().item() >= tgt_len - 1
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):
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logger.warning("alignment size mismatch found, skipping alignment!")
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return False
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return True
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def compute_alignment_weights(alignments):
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"""
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Given a tensor of shape [:, 2] containing the source-target indices
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corresponding to the alignments, a weight vector containing the
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inverse frequency of each target index is computed.
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For e.g. if alignments = [[5, 7], [2, 3], [1, 3], [4, 2]], then
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a tensor containing [1., 0.5, 0.5, 1] should be returned (since target
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index 3 is repeated twice)
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"""
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align_tgt = alignments[:, 1]
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_, align_tgt_i, align_tgt_c = torch.unique(
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align_tgt, return_inverse=True, return_counts=True
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)
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align_weights = align_tgt_c[align_tgt_i[np.arange(len(align_tgt))]]
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return 1.0 / align_weights.float()
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id = torch.LongTensor([s["id"] for s in samples])
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src_tokens = merge(
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"source",
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left_pad=left_pad_source,
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pad_to_length=pad_to_length["source"] if pad_to_length is not None else None,
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)
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# sort by descending source length
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src_lengths = torch.LongTensor(
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[s["source"].ne(pad_idx).long().sum() for s in samples]
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)
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src_lengths, sort_order = src_lengths.sort(descending=True)
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id = id.index_select(0, sort_order)
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src_tokens = src_tokens.index_select(0, sort_order)
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prev_output_tokens = None
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target = None
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if samples[0].get("target", None) is not None:
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target = merge(
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"target",
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left_pad=left_pad_target,
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pad_to_length=pad_to_length["target"]
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if pad_to_length is not None
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else None,
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)
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target = target.index_select(0, sort_order)
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tgt_lengths = torch.LongTensor(
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[s["target"].ne(pad_idx).long().sum() for s in samples]
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).index_select(0, sort_order)
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ntokens = tgt_lengths.sum().item()
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if samples[0].get("prev_output_tokens", None) is not None:
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prev_output_tokens = merge("prev_output_tokens", left_pad=left_pad_target)
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elif input_feeding:
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# we create a shifted version of targets for feeding the
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# previous output token(s) into the next decoder step
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prev_output_tokens = merge(
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"target",
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left_pad=left_pad_target,
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move_eos_to_beginning=True,
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pad_to_length=pad_to_length["target"]
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if pad_to_length is not None
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else None,
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)
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else:
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ntokens = src_lengths.sum().item()
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batch = {
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"id": id,
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"nsentences": len(samples),
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"ntokens": ntokens,
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"net_input": {
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"src_tokens": src_tokens,
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"src_lengths": src_lengths,
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},
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"target": target,
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}
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if prev_output_tokens is not None:
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batch["net_input"]["prev_output_tokens"] = prev_output_tokens.index_select(
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0, sort_order
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)
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if samples[0].get("alignment", None) is not None:
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bsz, tgt_sz = batch["target"].shape
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src_sz = batch["net_input"]["src_tokens"].shape[1]
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offsets = torch.zeros((len(sort_order), 2), dtype=torch.long)
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offsets[:, 1] += torch.arange(len(sort_order), dtype=torch.long) * tgt_sz
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if left_pad_source:
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offsets[:, 0] += src_sz - src_lengths
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if left_pad_target:
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offsets[:, 1] += tgt_sz - tgt_lengths
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alignments = [
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alignment + offset
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for align_idx, offset, src_len, tgt_len in zip(
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sort_order, offsets, src_lengths, tgt_lengths
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)
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for alignment in [samples[align_idx]["alignment"].view(-1, 2)]
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if check_alignment(alignment, src_len, tgt_len)
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]
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if len(alignments) > 0:
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alignments = torch.cat(alignments, dim=0)
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align_weights = compute_alignment_weights(alignments)
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batch["alignments"] = alignments
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batch["align_weights"] = align_weights
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if samples[0].get("constraints", None) is not None:
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# Collate the packed constraints across the samples, padding to
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# the length of the longest sample.
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lens = [sample.get("constraints").size(0) for sample in samples]
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max_len = max(lens)
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constraints = torch.zeros((len(samples), max(lens))).long()
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for i, sample in enumerate(samples):
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constraints[i, 0 : lens[i]] = samples[i].get("constraints")
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batch["constraints"] = constraints.index_select(0, sort_order)
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return batch
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class LanguagePairDataset(FairseqDataset):
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"""
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A pair of torch.utils.data.Datasets.
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Args:
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src (torch.utils.data.Dataset): source dataset to wrap
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src_sizes (List[int]): source sentence lengths
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src_dict (~fairseq.data.Dictionary): source vocabulary
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tgt (torch.utils.data.Dataset, optional): target dataset to wrap
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tgt_sizes (List[int], optional): target sentence lengths
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tgt_dict (~fairseq.data.Dictionary, optional): target vocabulary
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left_pad_source (bool, optional): pad source tensors on the left side
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(default: True).
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left_pad_target (bool, optional): pad target tensors on the left side
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(default: False).
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shuffle (bool, optional): shuffle dataset elements before batching
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(default: True).
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input_feeding (bool, optional): create a shifted version of the targets
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to be passed into the model for teacher forcing (default: True).
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remove_eos_from_source (bool, optional): if set, removes eos from end
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of source if it's present (default: False).
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append_eos_to_target (bool, optional): if set, appends eos to end of
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target if it's absent (default: False).
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align_dataset (torch.utils.data.Dataset, optional): dataset
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containing alignments.
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constraints (Tensor, optional): 2d tensor with a concatenated, zero-
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delimited list of constraints for each sentence.
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append_bos (bool, optional): if set, appends bos to the beginning of
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source/target sentence.
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num_buckets (int, optional): if set to a value greater than 0, then
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batches will be bucketed into the given number of batch shapes.
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src_lang_id (int, optional): source language ID, if set, the collated batch
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will contain a field 'src_lang_id' in 'net_input' which indicates the
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source language of the samples.
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tgt_lang_id (int, optional): target language ID, if set, the collated batch
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will contain a field 'tgt_lang_id' which indicates the target language
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of the samples.
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"""
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def __init__(
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self,
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src,
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src_sizes,
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src_dict,
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tgt=None,
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tgt_sizes=None,
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tgt_dict=None,
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left_pad_source=True,
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left_pad_target=False,
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shuffle=True,
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input_feeding=True,
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remove_eos_from_source=False,
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append_eos_to_target=False,
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align_dataset=None,
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constraints=None,
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append_bos=False,
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eos=None,
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num_buckets=0,
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src_lang_id=None,
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tgt_lang_id=None,
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pad_to_multiple=1,
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):
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if tgt_dict is not None:
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assert src_dict.pad() == tgt_dict.pad()
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assert src_dict.eos() == tgt_dict.eos()
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assert src_dict.unk() == tgt_dict.unk()
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if tgt is not None:
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assert len(src) == len(
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tgt
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), "Source and target must contain the same number of examples"
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self.src = src
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self.tgt = tgt
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self.src_sizes = np.array(src_sizes)
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self.tgt_sizes = np.array(tgt_sizes) if tgt_sizes is not None else None
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self.sizes = (
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np.vstack((self.src_sizes, self.tgt_sizes)).T
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if self.tgt_sizes is not None
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else self.src_sizes
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)
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self.src_dict = src_dict
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self.tgt_dict = tgt_dict
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self.left_pad_source = left_pad_source
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self.left_pad_target = left_pad_target
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self.shuffle = shuffle
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self.input_feeding = input_feeding
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self.remove_eos_from_source = remove_eos_from_source
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self.append_eos_to_target = append_eos_to_target
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self.align_dataset = align_dataset
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if self.align_dataset is not None:
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assert (
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self.tgt_sizes is not None
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), "Both source and target needed when alignments are provided"
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self.constraints = constraints
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self.append_bos = append_bos
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self.eos = eos if eos is not None else src_dict.eos()
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self.src_lang_id = src_lang_id
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self.tgt_lang_id = tgt_lang_id
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if num_buckets > 0:
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from fairseq.data import BucketPadLengthDataset
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self.src = BucketPadLengthDataset(
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self.src,
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sizes=self.src_sizes,
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num_buckets=num_buckets,
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pad_idx=self.src_dict.pad(),
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left_pad=self.left_pad_source,
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)
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self.src_sizes = self.src.sizes
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logger.info("bucketing source lengths: {}".format(list(self.src.buckets)))
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if self.tgt is not None:
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self.tgt = BucketPadLengthDataset(
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self.tgt,
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sizes=self.tgt_sizes,
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num_buckets=num_buckets,
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pad_idx=self.tgt_dict.pad(),
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left_pad=self.left_pad_target,
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)
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self.tgt_sizes = self.tgt.sizes
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logger.info(
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"bucketing target lengths: {}".format(list(self.tgt.buckets))
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)
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# determine bucket sizes using self.num_tokens, which will return
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# the padded lengths (thanks to BucketPadLengthDataset)
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num_tokens = np.vectorize(self.num_tokens, otypes=[np.compat.long])
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self.bucketed_num_tokens = num_tokens(np.arange(len(self.src)))
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self.buckets = [
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(None, num_tokens) for num_tokens in np.unique(self.bucketed_num_tokens)
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]
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else:
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self.buckets = None
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self.pad_to_multiple = pad_to_multiple
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def get_batch_shapes(self):
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return self.buckets
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def __getitem__(self, index):
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tgt_item = self.tgt[index] if self.tgt is not None else None
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src_item = self.src[index]
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# Append EOS to end of tgt sentence if it does not have an EOS and remove
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# EOS from end of src sentence if it exists. This is useful when we use
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# use existing datasets for opposite directions i.e., when we want to
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# use tgt_dataset as src_dataset and vice versa
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if self.append_eos_to_target:
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eos = self.tgt_dict.eos() if self.tgt_dict else self.src_dict.eos()
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if self.tgt and self.tgt[index][-1] != eos:
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tgt_item = torch.cat([self.tgt[index], torch.LongTensor([eos])])
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if self.append_bos:
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bos = self.tgt_dict.bos() if self.tgt_dict else self.src_dict.bos()
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if self.tgt and self.tgt[index][0] != bos:
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tgt_item = torch.cat([torch.LongTensor([bos]), self.tgt[index]])
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bos = self.src_dict.bos()
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if self.src[index][0] != bos:
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src_item = torch.cat([torch.LongTensor([bos]), self.src[index]])
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if self.remove_eos_from_source:
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eos = self.src_dict.eos()
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if self.src[index][-1] == eos:
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src_item = self.src[index][:-1]
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example = {
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"id": index,
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"source": src_item,
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"target": tgt_item,
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}
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if self.align_dataset is not None:
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example["alignment"] = self.align_dataset[index]
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if self.constraints is not None:
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example["constraints"] = self.constraints[index]
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return example
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def __len__(self):
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return len(self.src)
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def collater(self, samples, pad_to_length=None):
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"""Merge a list of samples to form a mini-batch.
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Args:
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samples (List[dict]): samples to collate
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pad_to_length (dict, optional): a dictionary of
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{'source': source_pad_to_length, 'target': target_pad_to_length}
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to indicate the max length to pad to in source and target respectively.
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Returns:
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dict: a mini-batch with the following keys:
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- `id` (LongTensor): example IDs in the original input order
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- `ntokens` (int): total number of tokens in the batch
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- `net_input` (dict): the input to the Model, containing keys:
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- `src_tokens` (LongTensor): a padded 2D Tensor of tokens in
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the source sentence of shape `(bsz, src_len)`. Padding will
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appear on the left if *left_pad_source* is ``True``.
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- `src_lengths` (LongTensor): 1D Tensor of the unpadded
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lengths of each source sentence of shape `(bsz)`
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- `prev_output_tokens` (LongTensor): a padded 2D Tensor of
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tokens in the target sentence, shifted right by one
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position for teacher forcing, of shape `(bsz, tgt_len)`.
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This key will not be present if *input_feeding* is
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``False``. Padding will appear on the left if
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*left_pad_target* is ``True``.
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- `src_lang_id` (LongTensor): a long Tensor which contains source
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language IDs of each sample in the batch
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- `target` (LongTensor): a padded 2D Tensor of tokens in the
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target sentence of shape `(bsz, tgt_len)`. Padding will appear
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on the left if *left_pad_target* is ``True``.
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- `tgt_lang_id` (LongTensor): a long Tensor which contains target language
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IDs of each sample in the batch
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"""
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res = collate(
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samples,
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pad_idx=self.src_dict.pad(),
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eos_idx=self.eos,
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left_pad_source=self.left_pad_source,
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left_pad_target=self.left_pad_target,
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input_feeding=self.input_feeding,
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pad_to_length=pad_to_length,
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pad_to_multiple=self.pad_to_multiple,
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)
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if self.src_lang_id is not None or self.tgt_lang_id is not None:
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src_tokens = res["net_input"]["src_tokens"]
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bsz = src_tokens.size(0)
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if self.src_lang_id is not None:
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res["net_input"]["src_lang_id"] = (
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torch.LongTensor([[self.src_lang_id]]).expand(bsz, 1).to(src_tokens)
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)
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if self.tgt_lang_id is not None:
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res["tgt_lang_id"] = (
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torch.LongTensor([[self.tgt_lang_id]]).expand(bsz, 1).to(src_tokens)
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)
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return res
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def num_tokens(self, index):
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"""Return the number of tokens in a sample. This value is used to
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enforce ``--max-tokens`` during batching."""
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return max(
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self.src_sizes[index],
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self.tgt_sizes[index] if self.tgt_sizes is not None else 0,
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)
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def num_tokens_vec(self, indices):
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"""Return the number of tokens for a set of positions defined by indices.
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This value is used to enforce ``--max-tokens`` during batching."""
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sizes = self.src_sizes[indices]
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if self.tgt_sizes is not None:
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sizes = np.maximum(sizes, self.tgt_sizes[indices])
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return sizes
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def size(self, index):
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"""Return an example's size as a float or tuple. This value is used when
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filtering a dataset with ``--max-positions``."""
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return (
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self.src_sizes[index],
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self.tgt_sizes[index] if self.tgt_sizes is not None else 0,
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)
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def ordered_indices(self):
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"""Return an ordered list of indices. Batches will be constructed based
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on this order."""
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if self.shuffle:
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indices = np.random.permutation(len(self)).astype(np.int64)
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else:
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indices = np.arange(len(self), dtype=np.int64)
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if self.buckets is None:
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# sort by target length, then source length
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if self.tgt_sizes is not None:
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indices = indices[np.argsort(self.tgt_sizes[indices], kind="mergesort")]
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return indices[np.argsort(self.src_sizes[indices], kind="mergesort")]
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else:
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# sort by bucketed_num_tokens, which is:
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# max(padded_src_len, padded_tgt_len)
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return indices[
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np.argsort(self.bucketed_num_tokens[indices], kind="mergesort")
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]
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@property
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def supports_prefetch(self):
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return getattr(self.src, "supports_prefetch", False) and (
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getattr(self.tgt, "supports_prefetch", False) or self.tgt is None
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)
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def prefetch(self, indices):
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self.src.prefetch(indices)
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if self.tgt is not None:
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self.tgt.prefetch(indices)
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if self.align_dataset is not None:
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self.align_dataset.prefetch(indices)
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def filter_indices_by_size(self, indices, max_sizes):
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"""Filter a list of sample indices. Remove those that are longer
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than specified in max_sizes.
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Args:
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indices (np.array): original array of sample indices
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max_sizes (int or list[int] or tuple[int]): max sample size,
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can be defined separately for src and tgt (then list or tuple)
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Returns:
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np.array: filtered sample array
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list: list of removed indices
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"""
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return data_utils.filter_paired_dataset_indices_by_size(
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self.src_sizes,
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self.tgt_sizes,
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indices,
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|
max_sizes,
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|
)
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