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| 1 | +# -*- coding: utf-8 -*- |
| 2 | +""" |
| 3 | + |
| 4 | +@description: |
| 5 | +""" |
| 6 | + |
| 7 | +from typing import Iterator, List, Dict |
| 8 | +import torch |
| 9 | +import torch.optim as optim |
| 10 | +import numpy as np |
| 11 | +from allennlp.data import Instance |
| 12 | +from allennlp.data.fields import TextField, SequenceLabelField |
| 13 | +from allennlp.data.dataset_readers import DatasetReader |
| 14 | +from allennlp.common.file_utils import cached_path |
| 15 | +from allennlp.data.token_indexers import TokenIndexer, SingleIdTokenIndexer |
| 16 | +from allennlp.data.tokenizers import Token |
| 17 | +from allennlp.data.vocabulary import Vocabulary |
| 18 | +from allennlp.models import Model |
| 19 | +from allennlp.modules.text_field_embedders import TextFieldEmbedder, BasicTextFieldEmbedder |
| 20 | +from allennlp.modules.token_embedders import Embedding |
| 21 | +from allennlp.modules.seq2seq_encoders import Seq2SeqEncoder, PytorchSeq2SeqWrapper |
| 22 | +from allennlp.nn.util import get_text_field_mask, sequence_cross_entropy_with_logits |
| 23 | +from allennlp.training.metrics import CategoricalAccuracy |
| 24 | +from allennlp.data.iterators import BucketIterator |
| 25 | +from allennlp.training.trainer import Trainer |
| 26 | +from allennlp.predictors import SentenceTaggerPredictor |
| 27 | + |
| 28 | +torch.manual_seed(1) |
| 29 | + |
| 30 | + |
| 31 | +class PosDatasetReader(DatasetReader): |
| 32 | + """ |
| 33 | + DatasetReader for PoS tagging data, one sentence per line, like |
| 34 | +
|
| 35 | + The###DET dog###NN ate###V the###DET apple###NN |
| 36 | + """ |
| 37 | + |
| 38 | + def __init__(self, token_indexers: Dict[str, TokenIndexer] = None) -> None: |
| 39 | + super().__init__(lazy=False) |
| 40 | + self.token_indexers = token_indexers or {"tokens": SingleIdTokenIndexer()} |
| 41 | + |
| 42 | + def text_to_instance(self, tokens: List[Token], tags: List[str] = None) -> Instance: |
| 43 | + sentence_field = TextField(tokens, self.token_indexers) |
| 44 | + fields = {"sentence": sentence_field} |
| 45 | + |
| 46 | + if tags: |
| 47 | + label_field = SequenceLabelField(labels=tags, sequence_field=sentence_field) |
| 48 | + fields["labels"] = label_field |
| 49 | + |
| 50 | + return Instance(fields) |
| 51 | + |
| 52 | + def _read(self, file_path: str) -> Iterator[Instance]: |
| 53 | + with open(file_path) as f: |
| 54 | + for line in f: |
| 55 | + pairs = line.strip().split() |
| 56 | + sentence, tags = zip(*(pair.split("###") for pair in pairs)) |
| 57 | + yield self.text_to_instance([Token(word) for word in sentence], tags) |
| 58 | + |
| 59 | + |
| 60 | +class LstmTagger(Model): |
| 61 | + def __init__(self, |
| 62 | + word_embeddings: TextFieldEmbedder, |
| 63 | + encoder: Seq2SeqEncoder, |
| 64 | + vocab: Vocabulary) -> None: |
| 65 | + super().__init__(vocab) |
| 66 | + self.word_embeddings = word_embeddings |
| 67 | + self.encoder = encoder |
| 68 | + self.hidden2tag = torch.nn.Linear(in_features=encoder.get_output_dim(), |
| 69 | + out_features=vocab.get_vocab_size('labels')) |
| 70 | + self.accuracy = CategoricalAccuracy() |
| 71 | + |
| 72 | + def forward(self, |
| 73 | + sentence: Dict[str, torch.Tensor], |
| 74 | + labels: torch.Tensor = None) -> torch.Tensor: |
| 75 | + mask = get_text_field_mask(sentence) |
| 76 | + embeddings = self.word_embeddings(sentence) |
| 77 | + encoder_out = self.encoder(embeddings, mask) |
| 78 | + tag_logits = self.hidden2tag(encoder_out) |
| 79 | + output = {"tag_logits": tag_logits} |
| 80 | + if labels is not None: |
| 81 | + self.accuracy(tag_logits, labels, mask) |
| 82 | + output["loss"] = sequence_cross_entropy_with_logits(tag_logits, labels, mask) |
| 83 | + |
| 84 | + return output |
| 85 | + |
| 86 | + def get_metrics(self, reset: bool = False) -> Dict[str, float]: |
| 87 | + return {"accuracy": self.accuracy.get_metric(reset)} |
| 88 | + |
| 89 | + |
| 90 | +reader = PosDatasetReader() |
| 91 | +train_dataset = reader.read(cached_path( |
| 92 | + 'https://raw.githubusercontent.com/allenai/allennlp' |
| 93 | + '/master/tutorials/tagger/training.txt')) |
| 94 | +validation_dataset = reader.read(cached_path( |
| 95 | + 'https://raw.githubusercontent.com/allenai/allennlp' |
| 96 | + '/master/tutorials/tagger/validation.txt')) |
| 97 | +vocab = Vocabulary.from_instances(train_dataset + validation_dataset) |
| 98 | +EMBEDDING_DIM = 6 |
| 99 | +HIDDEN_DIM = 6 |
| 100 | +token_embedding = Embedding(num_embeddings=vocab.get_vocab_size('tokens'), |
| 101 | + embedding_dim=EMBEDDING_DIM) |
| 102 | +word_embeddings = BasicTextFieldEmbedder({"tokens": token_embedding}) |
| 103 | +lstm = PytorchSeq2SeqWrapper(torch.nn.LSTM(EMBEDDING_DIM, HIDDEN_DIM, batch_first=True)) |
| 104 | +model = LstmTagger(word_embeddings, lstm, vocab) |
| 105 | +optimizer = optim.SGD(model.parameters(), lr=0.1) |
| 106 | +iterator = BucketIterator(batch_size=2, sorting_keys=[("sentence", "num_tokens")]) |
| 107 | +iterator.index_with(vocab) |
| 108 | +trainer = Trainer(model=model, |
| 109 | + optimizer=optimizer, |
| 110 | + iterator=iterator, |
| 111 | + train_dataset=train_dataset, |
| 112 | + validation_dataset=validation_dataset, |
| 113 | + patience=10, |
| 114 | + num_epochs=800) |
| 115 | +trainer.train() |
| 116 | +predictor = SentenceTaggerPredictor(model, dataset_reader=reader) |
| 117 | +tag_logits = predictor.predict("The dog ate the apple")['tag_logits'] |
| 118 | +tag_ids = np.argmax(tag_logits, axis=-1) |
| 119 | +print([model.vocab.get_token_from_index(i, 'labels') for i in tag_ids]) |
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