# Copyright 2014-2020 by Christopher C. Little.
# This file is part of Abydos.
#
# Abydos is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Abydos is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Abydos. If not, see <http://www.gnu.org/licenses/>.
"""abydos.stemmer._snowball_swedish.
Snowball Swedish stemmer
"""
from unicodedata import normalize
from deprecation import deprecated
from ._snowball import _Snowball
from .. import __version__
__all__ = ['SnowballSwedish', 'sb_swedish']
[docs]class SnowballSwedish(_Snowball):
"""Snowball Swedish stemmer.
The Snowball Swedish stemmer is defined at:
http://snowball.tartarus.org/algorithms/swedish/stemmer.html
.. versionadded:: 0.3.6
"""
_vowels = {'a', 'e', 'i', 'o', 'u', 'y', 'ä', 'å', 'ö'}
_s_endings = {
'b',
'c',
'd',
'f',
'g',
'h',
'j',
'k',
'l',
'm',
'n',
'o',
'p',
'r',
't',
'v',
'y',
}
[docs] def stem(self, word):
"""Return Snowball Swedish stem.
Parameters
----------
word : str
The word to stem
Returns
-------
str
Word stem
Examples
--------
>>> stmr = SnowballSwedish()
>>> stmr.stem('undervisa')
'undervis'
>>> stmr.stem('suspension')
'suspension'
>>> stmr.stem('visshet')
'viss'
.. versionadded:: 0.1.0
.. versionchanged:: 0.3.6
Encapsulated in class
"""
# lowercase, normalize, and compose
word = normalize('NFC', word.lower())
r1_start = min(max(3, self._sb_r1(word)), len(word))
# Step 1
_r1 = word[r1_start:]
if _r1[-7:] == 'heterna':
word = word[:-7]
elif _r1[-6:] == 'hetens':
word = word[:-6]
elif _r1[-5:] in {
'anden',
'heten',
'heter',
'arnas',
'ernas',
'ornas',
'andes',
'arens',
'andet',
}:
word = word[:-5]
elif _r1[-4:] in {
'arna',
'erna',
'orna',
'ande',
'arne',
'aste',
'aren',
'ades',
'erns',
}:
word = word[:-4]
elif _r1[-3:] in {'ade', 'are', 'ern', 'ens', 'het', 'ast'}:
word = word[:-3]
elif _r1[-2:] in {'ad', 'en', 'ar', 'er', 'or', 'as', 'es', 'at'}:
word = word[:-2]
elif _r1[-1:] in {'a', 'e'}:
word = word[:-1]
elif _r1[-1:] == 's':
if len(word) > 1 and word[-2] in self._s_endings:
word = word[:-1]
# Step 2
if word[r1_start:][-2:] in {'dd', 'gd', 'nn', 'dt', 'gt', 'kt', 'tt'}:
word = word[:-1]
# Step 3
_r1 = word[r1_start:]
if _r1[-5:] == 'fullt':
word = word[:-1]
elif _r1[-4:] == 'löst':
word = word[:-1]
elif _r1[-3:] in {'lig', 'els'}:
word = word[:-3]
elif _r1[-2:] == 'ig':
word = word[:-2]
return word
[docs]@deprecated(
deprecated_in='0.4.0',
removed_in='0.6.0',
current_version=__version__,
details='Use the SnowballSwedish.stem method instead.',
)
def sb_swedish(word):
"""Return Snowball Swedish stem.
This is a wrapper for :py:meth:`SnowballSwedish.stem`.
Parameters
----------
word : str
The word to stem
Returns
-------
str
Word stem
Examples
--------
>>> sb_swedish('undervisa')
'undervis'
>>> sb_swedish('suspension')
'suspension'
>>> sb_swedish('visshet')
'viss'
.. versionadded:: 0.1.0
"""
return SnowballSwedish().stem(word)
if __name__ == '__main__':
import doctest
doctest.testmod()