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66 lines
1.8 KiB
Python
66 lines
1.8 KiB
Python
# Copyright 2021 DeepMind Technologies Limited
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Tokenizer implementation mapping strings to their UTF-8 bytes."""
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from typing import Union
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import numpy as np
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class BytesTokenizer:
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"""Tokenizes string to utf-8 bytes."""
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def __init__(self):
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self._num_reserved_tokens = 6 # PAD, BOS, EOS, MASK, CLS, SEP
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def to_string(self, inputs: np.ndarray) -> str:
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inputs_no_special = (
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inputs[inputs >= self._num_reserved_tokens] - self._num_reserved_tokens)
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decoded_bytes = inputs_no_special.astype(np.uint8).tobytes()
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return decoded_bytes.decode('utf-8', errors='replace')
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def to_int(self, inputs: Union[str, bytes]) -> np.ndarray:
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if isinstance(inputs, str):
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inputs = inputs.encode('utf-8')
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encoded = np.frombuffer(inputs, np.uint8).astype(np.int32)
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encoded = encoded + self._num_reserved_tokens
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return encoded.astype(np.int32)
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@property
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def vocab_size(self) -> int:
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return 256 + self._num_reserved_tokens
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@property
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def pad_token(self) -> int:
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return 0
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@property
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def bos_token(self) -> int:
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return 1
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@property
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def eos_token(self) -> int:
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return 2
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@property
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def mask_token(self) -> int:
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return 3
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@property
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def cls_token(self) -> int:
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return 4
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@property
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def sep_token(self) -> int:
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return 5
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