152 lines
5.4 KiB
Python
152 lines
5.4 KiB
Python
from typing import Dict, Iterator, List, Optional, Union
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from tokenizers import AddedToken, Tokenizer, decoders, trainers
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from tokenizers.models import WordPiece
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from tokenizers.normalizers import BertNormalizer
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from tokenizers.pre_tokenizers import BertPreTokenizer
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from tokenizers.processors import BertProcessing
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from .base_tokenizer import BaseTokenizer
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class BertWordPieceTokenizer(BaseTokenizer):
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"""Bert WordPiece Tokenizer"""
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def __init__(
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self,
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vocab: Optional[Union[str, Dict[str, int]]] = None,
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unk_token: Union[str, AddedToken] = "[UNK]",
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sep_token: Union[str, AddedToken] = "[SEP]",
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cls_token: Union[str, AddedToken] = "[CLS]",
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pad_token: Union[str, AddedToken] = "[PAD]",
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mask_token: Union[str, AddedToken] = "[MASK]",
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clean_text: bool = True,
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handle_chinese_chars: bool = True,
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strip_accents: Optional[bool] = None,
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lowercase: bool = True,
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wordpieces_prefix: str = "##",
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):
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if vocab is not None:
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tokenizer = Tokenizer(WordPiece(vocab, unk_token=str(unk_token)))
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else:
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tokenizer = Tokenizer(WordPiece(unk_token=str(unk_token)))
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# Let the tokenizer know about special tokens if they are part of the vocab
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if tokenizer.token_to_id(str(unk_token)) is not None:
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tokenizer.add_special_tokens([str(unk_token)])
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if tokenizer.token_to_id(str(sep_token)) is not None:
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tokenizer.add_special_tokens([str(sep_token)])
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if tokenizer.token_to_id(str(cls_token)) is not None:
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tokenizer.add_special_tokens([str(cls_token)])
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if tokenizer.token_to_id(str(pad_token)) is not None:
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tokenizer.add_special_tokens([str(pad_token)])
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if tokenizer.token_to_id(str(mask_token)) is not None:
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tokenizer.add_special_tokens([str(mask_token)])
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tokenizer.normalizer = BertNormalizer(
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clean_text=clean_text,
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handle_chinese_chars=handle_chinese_chars,
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strip_accents=strip_accents,
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lowercase=lowercase,
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)
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tokenizer.pre_tokenizer = BertPreTokenizer()
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if vocab is not None:
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sep_token_id = tokenizer.token_to_id(str(sep_token))
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if sep_token_id is None:
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raise TypeError("sep_token not found in the vocabulary")
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cls_token_id = tokenizer.token_to_id(str(cls_token))
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if cls_token_id is None:
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raise TypeError("cls_token not found in the vocabulary")
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tokenizer.post_processor = BertProcessing((str(sep_token), sep_token_id), (str(cls_token), cls_token_id))
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tokenizer.decoder = decoders.WordPiece(prefix=wordpieces_prefix)
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parameters = {
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"model": "BertWordPiece",
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"unk_token": unk_token,
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"sep_token": sep_token,
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"cls_token": cls_token,
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"pad_token": pad_token,
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"mask_token": mask_token,
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"clean_text": clean_text,
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"handle_chinese_chars": handle_chinese_chars,
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"strip_accents": strip_accents,
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"lowercase": lowercase,
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"wordpieces_prefix": wordpieces_prefix,
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}
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super().__init__(tokenizer, parameters)
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@staticmethod
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def from_file(vocab: str, **kwargs):
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vocab = WordPiece.read_file(vocab)
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return BertWordPieceTokenizer(vocab, **kwargs)
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def train(
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self,
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files: Union[str, List[str]],
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vocab_size: int = 30000,
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min_frequency: int = 2,
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limit_alphabet: int = 1000,
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initial_alphabet: List[str] = [],
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special_tokens: List[Union[str, AddedToken]] = [
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"[PAD]",
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"[UNK]",
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"[CLS]",
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"[SEP]",
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"[MASK]",
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],
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show_progress: bool = True,
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wordpieces_prefix: str = "##",
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):
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"""Train the model using the given files"""
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trainer = trainers.WordPieceTrainer(
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vocab_size=vocab_size,
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min_frequency=min_frequency,
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limit_alphabet=limit_alphabet,
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initial_alphabet=initial_alphabet,
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special_tokens=special_tokens,
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show_progress=show_progress,
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continuing_subword_prefix=wordpieces_prefix,
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)
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if isinstance(files, str):
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files = [files]
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self._tokenizer.train(files, trainer=trainer)
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def train_from_iterator(
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self,
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iterator: Union[Iterator[str], Iterator[Iterator[str]]],
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vocab_size: int = 30000,
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min_frequency: int = 2,
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limit_alphabet: int = 1000,
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initial_alphabet: List[str] = [],
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special_tokens: List[Union[str, AddedToken]] = [
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"[PAD]",
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"[UNK]",
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"[CLS]",
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"[SEP]",
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"[MASK]",
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],
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show_progress: bool = True,
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wordpieces_prefix: str = "##",
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length: Optional[int] = None,
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):
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"""Train the model using the given iterator"""
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trainer = trainers.WordPieceTrainer(
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vocab_size=vocab_size,
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min_frequency=min_frequency,
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limit_alphabet=limit_alphabet,
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initial_alphabet=initial_alphabet,
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special_tokens=special_tokens,
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show_progress=show_progress,
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continuing_subword_prefix=wordpieces_prefix,
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)
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self._tokenizer.train_from_iterator(
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iterator,
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trainer=trainer,
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length=length,
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)
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