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| # Natural Language Toolkit: SentiWordNet | |
| # | |
| # Copyright (C) 2001-2023 NLTK Project | |
| # Author: Christopher Potts <[email protected]> | |
| # URL: <https://www.nltk.org/> | |
| # For license information, see LICENSE.TXT | |
| """ | |
| An NLTK interface for SentiWordNet | |
| SentiWordNet is a lexical resource for opinion mining. | |
| SentiWordNet assigns to each synset of WordNet three | |
| sentiment scores: positivity, negativity, and objectivity. | |
| For details about SentiWordNet see: | |
| http://sentiwordnet.isti.cnr.it/ | |
| >>> from nltk.corpus import sentiwordnet as swn | |
| >>> print(swn.senti_synset('breakdown.n.03')) | |
| <breakdown.n.03: PosScore=0.0 NegScore=0.25> | |
| >>> list(swn.senti_synsets('slow')) | |
| [SentiSynset('decelerate.v.01'), SentiSynset('slow.v.02'),\ | |
| SentiSynset('slow.v.03'), SentiSynset('slow.a.01'),\ | |
| SentiSynset('slow.a.02'), SentiSynset('dense.s.04'),\ | |
| SentiSynset('slow.a.04'), SentiSynset('boring.s.01'),\ | |
| SentiSynset('dull.s.08'), SentiSynset('slowly.r.01'),\ | |
| SentiSynset('behind.r.03')] | |
| >>> happy = swn.senti_synsets('happy', 'a') | |
| >>> happy0 = list(happy)[0] | |
| >>> happy0.pos_score() | |
| 0.875 | |
| >>> happy0.neg_score() | |
| 0.0 | |
| >>> happy0.obj_score() | |
| 0.125 | |
| """ | |
| import re | |
| from nltk.corpus.reader import CorpusReader | |
| class SentiWordNetCorpusReader(CorpusReader): | |
| def __init__(self, root, fileids, encoding="utf-8"): | |
| """ | |
| Construct a new SentiWordNet Corpus Reader, using data from | |
| the specified file. | |
| """ | |
| super().__init__(root, fileids, encoding=encoding) | |
| if len(self._fileids) != 1: | |
| raise ValueError("Exactly one file must be specified") | |
| self._db = {} | |
| self._parse_src_file() | |
| def _parse_src_file(self): | |
| lines = self.open(self._fileids[0]).read().splitlines() | |
| lines = filter((lambda x: not re.search(r"^\s*#", x)), lines) | |
| for i, line in enumerate(lines): | |
| fields = [field.strip() for field in re.split(r"\t+", line)] | |
| try: | |
| pos, offset, pos_score, neg_score, synset_terms, gloss = fields | |
| except BaseException as e: | |
| raise ValueError(f"Line {i} formatted incorrectly: {line}\n") from e | |
| if pos and offset: | |
| offset = int(offset) | |
| self._db[(pos, offset)] = (float(pos_score), float(neg_score)) | |
| def senti_synset(self, *vals): | |
| from nltk.corpus import wordnet as wn | |
| if tuple(vals) in self._db: | |
| pos_score, neg_score = self._db[tuple(vals)] | |
| pos, offset = vals | |
| if pos == "s": | |
| pos = "a" | |
| synset = wn.synset_from_pos_and_offset(pos, offset) | |
| return SentiSynset(pos_score, neg_score, synset) | |
| else: | |
| synset = wn.synset(vals[0]) | |
| pos = synset.pos() | |
| if pos == "s": | |
| pos = "a" | |
| offset = synset.offset() | |
| if (pos, offset) in self._db: | |
| pos_score, neg_score = self._db[(pos, offset)] | |
| return SentiSynset(pos_score, neg_score, synset) | |
| else: | |
| return None | |
| def senti_synsets(self, string, pos=None): | |
| from nltk.corpus import wordnet as wn | |
| sentis = [] | |
| synset_list = wn.synsets(string, pos) | |
| for synset in synset_list: | |
| sentis.append(self.senti_synset(synset.name())) | |
| sentis = filter(lambda x: x, sentis) | |
| return sentis | |
| def all_senti_synsets(self): | |
| from nltk.corpus import wordnet as wn | |
| for key, fields in self._db.items(): | |
| pos, offset = key | |
| pos_score, neg_score = fields | |
| synset = wn.synset_from_pos_and_offset(pos, offset) | |
| yield SentiSynset(pos_score, neg_score, synset) | |
| class SentiSynset: | |
| def __init__(self, pos_score, neg_score, synset): | |
| self._pos_score = pos_score | |
| self._neg_score = neg_score | |
| self._obj_score = 1.0 - (self._pos_score + self._neg_score) | |
| self.synset = synset | |
| def pos_score(self): | |
| return self._pos_score | |
| def neg_score(self): | |
| return self._neg_score | |
| def obj_score(self): | |
| return self._obj_score | |
| def __str__(self): | |
| """Prints just the Pos/Neg scores for now.""" | |
| s = "<" | |
| s += self.synset.name() + ": " | |
| s += "PosScore=%s " % self._pos_score | |
| s += "NegScore=%s" % self._neg_score | |
| s += ">" | |
| return s | |
| def __repr__(self): | |
| return "Senti" + repr(self.synset) | |