mirror of
https://github.com/Steffo99/unimore-bda-6.git
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126 lines
4.6 KiB
Python
126 lines
4.6 KiB
Python
import nltk
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import nltk.classify
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import nltk.sentiment
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import nltk.sentiment.util
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import logging
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import typing as t
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import itertools
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from .base import Input, Category, BaseSA, AlreadyTrainedError, NotTrainedError
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from ..log import count_passage
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TokenBag = list[str]
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IntermediateValue = t.TypeVar("IntermediateValue")
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Features = dict[str, int]
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log = logging.getLogger(__name__)
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class VanillaSA(BaseSA):
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"""
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A sentiment analyzer resembling the one implemented in structure the one implemented in the classroom, using the basic sentiment analyzer of NLTK.
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"""
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def __init__(self, *, extractor: t.Callable[[Input], tuple[str, IntermediateValue]], tokenizer: t.Callable[[str], TokenBag], categorizer: t.Callable[[IntermediateValue], Category]) -> None:
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super().__init__()
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self.model: nltk.sentiment.SentimentAnalyzer = nltk.sentiment.SentimentAnalyzer()
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self.trained: bool = False
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self.extractor: t.Callable[[Input], tuple[str, IntermediateValue]] = extractor
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self.tokenizer: t.Callable[[str], TokenBag] = tokenizer
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self.categorizer: t.Callable[[IntermediateValue], Category] = categorizer
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def __repr__(self):
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return f"<{self.__class__.__qualname__} {'trained' if self.trained else 'untrained'} tokenizer={self.extractor!r} categorizer={self.categorizer!r}>"
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@staticmethod
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def __data_to_tokenbag(data: tuple[TokenBag, Category]) -> TokenBag:
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"""
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Access the tokenbag of a data tuple.
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"""
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return data[0]
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def __add_feature_unigrams(self, dataset: t.Iterator[tuple[TokenBag, Category]]) -> None:
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"""
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Register the `nltk.sentiment.util.extract_unigram_feats` feature extrator on the model.
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"""
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tokenbags = map(self.__data_to_tokenbag, dataset)
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all_words = self.model.all_words(tokenbags, labeled=False)
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unigrams = self.model.unigram_word_feats(words=all_words, min_freq=4)
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self.model.add_feat_extractor(nltk.sentiment.util.extract_unigram_feats, unigrams=unigrams)
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def _add_features(self, dataset: t.Iterator[tuple[TokenBag, Category]]):
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"""
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Register new feature extractors on the `.model`.
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"""
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self.__add_feature_unigrams(dataset)
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def __extract_features(self, data: tuple[TokenBag, Category]) -> tuple[Features, Category]:
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"""
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Convert a (TokenBag, Category) tuple to a (Features, Category) tuple.
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Does not use `SentimentAnalyzer.apply_features` due to unexpected behaviour when using iterators.
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"""
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count_passage("processed_features", 100)
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return self.model.extract_features(data[0]), data[1]
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def _train_from_dataset(self, dataset: t.Iterator[tuple[TokenBag, Category]]) -> None:
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"""
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Train the model with the given training set.
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"""
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if self.trained:
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raise AlreadyTrainedError()
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dataset_1, dataset_2 = itertools.tee(dataset, 2)
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self._add_features(dataset_1)
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del dataset_1
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dataset_2 = map(self.__extract_features, dataset_2)
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self.model.classifier = nltk.classify.NaiveBayesClassifier.train(dataset_2)
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self.trained = True
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def _evaluate_from_dataset(self, dataset: t.Iterator[tuple[TokenBag, Category]]) -> dict:
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"""
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Perform a model evaluation with the given test set.
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"""
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if not self.trained:
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raise NotTrainedError()
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dataset_1 = map(self.__extract_features, dataset)
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# FIXME: This won't work with streams :(
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return self.model.evaluate(list(dataset_1))
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def _use_from_tokenbag(self, tokens: TokenBag) -> Category:
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"""
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Categorize the given token bag.
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"""
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if not self.trained:
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raise NotTrainedError()
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return self.model.classify(instance=tokens)
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def _extract_data(self, inp: Input) -> tuple[TokenBag, Category]:
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count_passage("processed_data", 100)
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text, value = self.extractor(inp)
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return self.tokenizer(text), self.categorizer(value)
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def _extract_dataset(self, inp: t.Iterator[Input]) -> list[tuple[TokenBag, Category]]:
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return map(self._extract_data, inp)
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def train(self, training_set: t.Iterator[Input]) -> None:
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dataset = self._extract_dataset(training_set)
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self._train_from_dataset(dataset)
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def evaluate(self, test_set: t.Iterator[Input]) -> dict:
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dataset = self._extract_dataset(test_set)
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return self._evaluate_from_dataset(dataset)
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def use(self, text: Input) -> Category:
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tokens = self.tokenizer(text)
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return self._use_from_tokenbag(tokens)
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__all__ = (
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"VanillaSA",
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)
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