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| # Natural Language Toolkit: Opinion Lexicon Corpus Reader | |
| # | |
| # Copyright (C) 2001-2023 NLTK Project | |
| # Author: Pierpaolo Pantone <[email protected]> | |
| # URL: <https://www.nltk.org/> | |
| # For license information, see LICENSE.TXT | |
| """ | |
| CorpusReader for the Opinion Lexicon. | |
| Opinion Lexicon information | |
| =========================== | |
| Authors: Minqing Hu and Bing Liu, 2004. | |
| Department of Computer Science | |
| University of Illinois at Chicago | |
| Contact: Bing Liu, [email protected] | |
| https://www.cs.uic.edu/~liub | |
| Distributed with permission. | |
| Related papers: | |
| - Minqing Hu and Bing Liu. "Mining and summarizing customer reviews". | |
| Proceedings of the ACM SIGKDD International Conference on Knowledge Discovery | |
| & Data Mining (KDD-04), Aug 22-25, 2004, Seattle, Washington, USA. | |
| - Bing Liu, Minqing Hu and Junsheng Cheng. "Opinion Observer: Analyzing and | |
| Comparing Opinions on the Web". Proceedings of the 14th International World | |
| Wide Web conference (WWW-2005), May 10-14, 2005, Chiba, Japan. | |
| """ | |
| from nltk.corpus.reader import WordListCorpusReader | |
| from nltk.corpus.reader.api import * | |
| class IgnoreReadmeCorpusView(StreamBackedCorpusView): | |
| """ | |
| This CorpusView is used to skip the initial readme block of the corpus. | |
| """ | |
| def __init__(self, *args, **kwargs): | |
| StreamBackedCorpusView.__init__(self, *args, **kwargs) | |
| # open self._stream | |
| self._open() | |
| # skip the readme block | |
| read_blankline_block(self._stream) | |
| # Set the initial position to the current stream position | |
| self._filepos = [self._stream.tell()] | |
| class OpinionLexiconCorpusReader(WordListCorpusReader): | |
| """ | |
| Reader for Liu and Hu opinion lexicon. Blank lines and readme are ignored. | |
| >>> from nltk.corpus import opinion_lexicon | |
| >>> opinion_lexicon.words() | |
| ['2-faced', '2-faces', 'abnormal', 'abolish', ...] | |
| The OpinionLexiconCorpusReader provides shortcuts to retrieve positive/negative | |
| words: | |
| >>> opinion_lexicon.negative() | |
| ['2-faced', '2-faces', 'abnormal', 'abolish', ...] | |
| Note that words from `words()` method are sorted by file id, not alphabetically: | |
| >>> opinion_lexicon.words()[0:10] # doctest: +NORMALIZE_WHITESPACE | |
| ['2-faced', '2-faces', 'abnormal', 'abolish', 'abominable', 'abominably', | |
| 'abominate', 'abomination', 'abort', 'aborted'] | |
| >>> sorted(opinion_lexicon.words())[0:10] # doctest: +NORMALIZE_WHITESPACE | |
| ['2-faced', '2-faces', 'a+', 'abnormal', 'abolish', 'abominable', 'abominably', | |
| 'abominate', 'abomination', 'abort'] | |
| """ | |
| CorpusView = IgnoreReadmeCorpusView | |
| def words(self, fileids=None): | |
| """ | |
| Return all words in the opinion lexicon. Note that these words are not | |
| sorted in alphabetical order. | |
| :param fileids: a list or regexp specifying the ids of the files whose | |
| words have to be returned. | |
| :return: the given file(s) as a list of words and punctuation symbols. | |
| :rtype: list(str) | |
| """ | |
| if fileids is None: | |
| fileids = self._fileids | |
| elif isinstance(fileids, str): | |
| fileids = [fileids] | |
| return concat( | |
| [ | |
| self.CorpusView(path, self._read_word_block, encoding=enc) | |
| for (path, enc, fileid) in self.abspaths(fileids, True, True) | |
| ] | |
| ) | |
| def positive(self): | |
| """ | |
| Return all positive words in alphabetical order. | |
| :return: a list of positive words. | |
| :rtype: list(str) | |
| """ | |
| return self.words("positive-words.txt") | |
| def negative(self): | |
| """ | |
| Return all negative words in alphabetical order. | |
| :return: a list of negative words. | |
| :rtype: list(str) | |
| """ | |
| return self.words("negative-words.txt") | |
| def _read_word_block(self, stream): | |
| words = [] | |
| for i in range(20): # Read 20 lines at a time. | |
| line = stream.readline() | |
| if not line: | |
| continue | |
| words.append(line.strip()) | |
| return words | |