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131 lines
3.5 KiB
131 lines
3.5 KiB
# Copyright (c) 2020 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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from collections import OrderedDict
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from typing import Iterable
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__all__ = ["Vocab"]
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class Vocab(object):
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""" Vocabulary.
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Parameters
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-----------
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symbols: Iterable[str]
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Common symbols.
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padding_symbol: str, optional
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Symbol for pad. Defaults to "<pad>".
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unk_symbol: str, optional
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Symbol for unknow. Defaults to "<unk>"
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start_symbol: str, optional
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Symbol for start. Defaults to "<s>"
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end_symbol: str, optional
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Symbol for end. Defaults to "</s>"
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"""
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def __init__(self,
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symbols: Iterable[str],
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padding_symbol="<pad>",
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unk_symbol="<unk>",
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start_symbol="<s>",
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end_symbol="</s>"):
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self.special_symbols = OrderedDict()
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for i, item in enumerate(
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[padding_symbol, unk_symbol, start_symbol, end_symbol]):
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if item:
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self.special_symbols[item] = len(self.special_symbols)
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self.padding_symbol = padding_symbol
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self.unk_symbol = unk_symbol
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self.start_symbol = start_symbol
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self.end_symbol = end_symbol
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self.stoi = OrderedDict()
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self.stoi.update(self.special_symbols)
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for i, s in enumerate(symbols):
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if s not in self.stoi:
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self.stoi[s] = len(self.stoi)
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self.itos = {v: k for k, v in self.stoi.items()}
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def __len__(self):
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return len(self.stoi)
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@property
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def num_specials(self):
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""" The number of special symbols.
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"""
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return len(self.special_symbols)
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# special tokens
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@property
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def padding_index(self):
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""" The index of padding symbol
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"""
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return self.stoi.get(self.padding_symbol, -1)
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@property
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def unk_index(self):
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"""The index of unknow symbol.
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"""
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return self.stoi.get(self.unk_symbol, -1)
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@property
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def start_index(self):
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"""The index of start symbol.
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"""
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return self.stoi.get(self.start_symbol, -1)
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@property
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def end_index(self):
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""" The index of end symbol.
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"""
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return self.stoi.get(self.end_symbol, -1)
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def __repr__(self):
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fmt = "Vocab(size: {},\nstoi:\n{})"
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return fmt.format(len(self), self.stoi)
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def __str__(self):
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return self.__repr__()
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def lookup(self, symbol):
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""" The index that symbol correspond.
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"""
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return self.stoi[symbol]
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def reverse(self, index):
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""" The symbol thar index cottespond.
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"""
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return self.itos[index]
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def add_symbol(self, symbol):
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""" Add a new symbol in vocab.
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"""
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if symbol in self.stoi:
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return
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N = len(self.stoi)
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self.stoi[symbol] = N
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self.itos[N] = symbol
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def add_symbols(self, symbols):
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""" Add multiple symbols in vocab.
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"""
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for symbol in symbols:
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self.add_symbol(symbol)
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