Source code for nltk.stem.regexp

# Natural Language Toolkit: Stemmers
#
# Copyright (C) 2001-2017 NLTK Project
# Author: Trevor Cohn <tacohn@cs.mu.oz.au>
#         Edward Loper <edloper@gmail.com>
#         Steven Bird <stevenbird1@gmail.com>
# URL: <http://nltk.org/>
# For license information, see LICENSE.TXT
from __future__ import unicode_literals
import re

from nltk.stem.api import StemmerI
from nltk.compat import python_2_unicode_compatible

@python_2_unicode_compatible
[docs]class RegexpStemmer(StemmerI): """ A stemmer that uses regular expressions to identify morphological affixes. Any substrings that match the regular expressions will be removed. >>> from nltk.stem import RegexpStemmer >>> st = RegexpStemmer('ing$|s$|e$|able$', min=4) >>> st.stem('cars') 'car' >>> st.stem('mass') 'mas' >>> st.stem('was') 'was' >>> st.stem('bee') 'bee' >>> st.stem('compute') 'comput' >>> st.stem('advisable') 'advis' :type regexp: str or regexp :param regexp: The regular expression that should be used to identify morphological affixes. :type min: int :param min: The minimum length of string to stem """ def __init__(self, regexp, min=0): if not hasattr(regexp, 'pattern'): regexp = re.compile(regexp) self._regexp = regexp self._min = min
[docs] def stem(self, word): if len(word) < self._min: return word else: return self._regexp.sub('', word)
def __repr__(self): return '<RegexpStemmer: {!r}>'.format(self._regexp.pattern)