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74 lines
2.4 KiB
74 lines
2.4 KiB
# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
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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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# http://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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# Modified from espnet(https://github.com/espnet/espnet)
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"""Length bonus module."""
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from typing import Any
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from typing import List
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from typing import Tuple
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import paddle
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from .scorer_interface import BatchScorerInterface
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class LengthBonus(BatchScorerInterface):
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"""Length bonus in beam search."""
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def __init__(self, n_vocab: int):
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"""Initialize class.
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Args:
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n_vocab (int): The number of tokens in vocabulary for beam search
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"""
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self.n = n_vocab
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def score(self, y, state, x):
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"""Score new token.
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Args:
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y (paddle.Tensor): 1D paddle.int64 prefix tokens.
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state: Scorer state for prefix tokens
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x (paddle.Tensor): 2D encoder feature that generates ys.
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Returns:
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tuple[paddle.Tensor, Any]: Tuple of
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paddle.float32 scores for next token (n_vocab)
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and None
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"""
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return paddle.to_tensor(
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[1.0], place=x.place, dtype=x.dtype).expand(self.n), None
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def batch_score(self,
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ys: paddle.Tensor,
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states: List[Any],
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xs: paddle.Tensor) -> Tuple[paddle.Tensor, List[Any]]:
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"""Score new token batch.
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Args:
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ys (paddle.Tensor): paddle.int64 prefix tokens (n_batch, ylen).
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states (List[Any]): Scorer states for prefix tokens.
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xs (paddle.Tensor):
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The encoder feature that generates ys (n_batch, xlen, n_feat).
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Returns:
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tuple[paddle.Tensor, List[Any]]: Tuple of
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batchfied scores for next token with shape of `(n_batch, n_vocab)`
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and next state list for ys.
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"""
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return (paddle.to_tensor([1.0], place=xs.place, dtype=xs.dtype).expand(
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ys.shape[0], self.n), None, )
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