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from typing import Dict, Iterator, List, Optional, Tuple, Union
from .. import AddedToken, Tokenizer, decoders, pre_tokenizers, trainers
from ..models import BPE
from ..normalizers import BertNormalizer, Lowercase, Sequence, unicode_normalizer_from_str
from .base_tokenizer import BaseTokenizer
class CharBPETokenizer(BaseTokenizer):
"""Original BPE Tokenizer
Represents the BPE algorithm, as introduced by Rico Sennrich
(https://arxiv.org/abs/1508.07909)
The defaults settings corresponds to OpenAI GPT BPE tokenizers and differs from the original
Sennrich subword-nmt implementation by the following options that you can deactivate:
- adding a normalizer to clean up the text (deactivate with `bert_normalizer=False`) by:
* removing any control characters and replacing all whitespaces by the classic one.
* handle chinese chars by putting spaces around them.
* strip all accents.
- spitting on punctuation in addition to whitespaces (deactivate it with
`split_on_whitespace_only=True`)
"""
def __init__(
self,
vocab: Optional[Union[str, Dict[str, int]]] = None,
merges: Optional[Union[str, Dict[Tuple[int, int], Tuple[int, int]]]] = None,
unk_token: Union[str, AddedToken] = "<unk>",
suffix: str = "</w>",
dropout: Optional[float] = None,
lowercase: bool = False,
unicode_normalizer: Optional[str] = None,
bert_normalizer: bool = True,
split_on_whitespace_only: bool = False,
):
if vocab is not None and merges is not None:
tokenizer = Tokenizer(
BPE(
vocab,
merges,
dropout=dropout,
unk_token=str(unk_token),
end_of_word_suffix=suffix,
)
)
else:
tokenizer = Tokenizer(BPE(unk_token=str(unk_token), dropout=dropout, end_of_word_suffix=suffix))
if tokenizer.token_to_id(str(unk_token)) is not None:
tokenizer.add_special_tokens([str(unk_token)])
# Check for Unicode normalization first (before everything else)
normalizers = []
if unicode_normalizer:
normalizers += [unicode_normalizer_from_str(unicode_normalizer)]
if bert_normalizer:
normalizers += [BertNormalizer(lowercase=False)]
if lowercase:
normalizers += [Lowercase()]
# Create the normalizer structure
if len(normalizers) > 0:
if len(normalizers) > 1:
tokenizer.normalizer = Sequence(normalizers)
else:
tokenizer.normalizer = normalizers[0]
if split_on_whitespace_only:
tokenizer.pre_tokenizer = pre_tokenizers.WhitespaceSplit()
else:
tokenizer.pre_tokenizer = pre_tokenizers.BertPreTokenizer()
tokenizer.decoder = decoders.BPEDecoder(suffix=suffix)
parameters = {
"model": "BPE",
"unk_token": unk_token,
"suffix": suffix,
"dropout": dropout,
"lowercase": lowercase,
"unicode_normalizer": unicode_normalizer,
"bert_normalizer": bert_normalizer,
"split_on_whitespace_only": split_on_whitespace_only,
}
super().__init__(tokenizer, parameters)
@staticmethod
def from_file(vocab_filename: str, merges_filename: str, **kwargs):
vocab, merges = BPE.read_file(vocab_filename, merges_filename)
return CharBPETokenizer(vocab, merges, **kwargs)
def train(
self,
files: Union[str, List[str]],
vocab_size: int = 30000,
min_frequency: int = 2,
special_tokens: List[Union[str, AddedToken]] = ["<unk>"],
limit_alphabet: int = 1000,
initial_alphabet: List[str] = [],
suffix: Optional[str] = "</w>",
show_progress: bool = True,
):
"""Train the model using the given files"""
trainer = trainers.BpeTrainer(
vocab_size=vocab_size,
min_frequency=min_frequency,
special_tokens=special_tokens,
limit_alphabet=limit_alphabet,
initial_alphabet=initial_alphabet,
end_of_word_suffix=suffix,
show_progress=show_progress,
)
if isinstance(files, str):
files = [files]
self._tokenizer.train(files, trainer=trainer)
def train_from_iterator(
self,
iterator: Union[Iterator[str], Iterator[Iterator[str]]],
vocab_size: int = 30000,
min_frequency: int = 2,
special_tokens: List[Union[str, AddedToken]] = ["<unk>"],
limit_alphabet: int = 1000,
initial_alphabet: List[str] = [],
suffix: Optional[str] = "</w>",
show_progress: bool = True,
length: Optional[int] = None,
):
"""Train the model using the given iterator"""
trainer = trainers.BpeTrainer(
vocab_size=vocab_size,
min_frequency=min_frequency,
special_tokens=special_tokens,
limit_alphabet=limit_alphabet,
initial_alphabet=initial_alphabet,
end_of_word_suffix=suffix,
show_progress=show_progress,
)
self._tokenizer.train_from_iterator(
iterator,
trainer=trainer,
length=length,
)
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