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# -*- coding: utf-8 -*- |
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# Copyright 2014-2018 by Christopher C. Little. |
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# This file is part of Abydos. |
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# |
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# Abydos is free software: you can redistribute it and/or modify |
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# it under the terms of the GNU General Public License as published by |
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# the Free Software Foundation, either version 3 of the License, or |
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# (at your option) any later version. |
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# |
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# Abydos is distributed in the hope that it will be useful, |
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# but WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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# GNU General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with Abydos. If not, see <http://www.gnu.org/licenses/>. |
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"""abydos.stemmer. |
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The stemmer module defines word stemmers including: |
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- the Lovins stemmer |
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- the Porter and Porter2 (Snowball English) stemmers |
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- Snowball stemmers for German, Dutch, Norwegian, Swedish, and Danish |
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- CLEF German, German plus, and Swedish stemmers |
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- Caumann's German stemmer |
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""" |
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from __future__ import unicode_literals |
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import unicodedata |
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from six import text_type |
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from six.moves import range |
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def lovins(word): |
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"""Return Lovins stem. |
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Lovins stemmer |
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The Lovins stemmer is described in Julie Beth Lovins's article at: |
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http://www.mt-archive.info/MT-1968-Lovins.pdf |
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:param word: the word to stem |
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:returns: word stem |
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:rtype: string |
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>>> lovins('reading') |
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'read' |
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>>> lovins('suspension') |
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'suspens' |
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>>> lovins('elusiveness') |
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'elus' |
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""" |
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# pylint: disable=too-many-branches, too-many-locals |
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# lowercase, normalize, and compose |
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word = unicodedata.normalize('NFC', text_type(word.lower())) |
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def cond_b(word, suffix_len): |
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"""Return Lovins' condition B.""" |
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return len(word)-suffix_len >= 3 |
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def cond_c(word, suffix_len): |
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"""Return Lovins' condition C.""" |
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return len(word)-suffix_len >= 4 |
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def cond_d(word, suffix_len): |
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"""Return Lovins' condition D.""" |
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return len(word)-suffix_len >= 5 |
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def cond_e(word, suffix_len): |
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"""Return Lovins' condition E.""" |
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return word[-suffix_len-1] != 'e' |
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def cond_f(word, suffix_len): |
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"""Return Lovins' condition F.""" |
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return (len(word)-suffix_len >= 3 and |
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word[-suffix_len-1] != 'e') |
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def cond_g(word, suffix_len): |
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"""Return Lovins' condition G.""" |
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return (len(word)-suffix_len >= 3 and |
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word[-suffix_len-1] == 'f') |
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def cond_h(word, suffix_len): |
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"""Return Lovins' condition H.""" |
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return (word[-suffix_len-1] == 't' or |
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word[-suffix_len-2:-suffix_len] == 'll') |
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def cond_i(word, suffix_len): |
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"""Return Lovins' condition I.""" |
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return word[-suffix_len-1] not in {'e', 'o'} |
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def cond_j(word, suffix_len): |
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"""Return Lovins' condition J.""" |
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return word[-suffix_len-1] not in {'a', 'e'} |
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def cond_k(word, suffix_len): |
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"""Return Lovins' condition K.""" |
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return (len(word)-suffix_len >= 3 and |
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(word[-suffix_len-1] in {'i', 'l'} or |
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(word[-suffix_len-3] == 'u' and word[-suffix_len-1] == 'e'))) |
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def cond_l(word, suffix_len): |
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"""Return Lovins' condition L.""" |
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return (word[-suffix_len-1] not in {'s', 'u', 'x'} or |
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word[-suffix_len-1] == 'os') |
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def cond_m(word, suffix_len): |
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"""Return Lovins' condition M.""" |
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return word[-suffix_len-1] not in {'a', 'c', 'e', 'm'} |
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def cond_n(word, suffix_len): |
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"""Return Lovins' condition N.""" |
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if len(word)-suffix_len >= 3: |
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if word[-suffix_len-3] == 's': |
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if len(word)-suffix_len >= 4: |
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return True |
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else: |
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return True |
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return False |
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def cond_o(word, suffix_len): |
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"""Return Lovins' condition O.""" |
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return word[-suffix_len-1] in {'i', 'l'} |
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def cond_p(word, suffix_len): |
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"""Return Lovins' condition P.""" |
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return word[-suffix_len-1] != 'c' |
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def cond_q(word, suffix_len): |
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"""Return Lovins' condition Q.""" |
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return (len(word)-suffix_len >= 3 and |
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word[-suffix_len-1] not in {'l', 'n'} |
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def cond_r(word, suffix_len): |
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"""Return Lovins' condition R.""" |
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return word[-suffix_len-1] in {'n', 'r'} |
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def cond_s(word, suffix_len): |
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"""Return Lovins' condition S.""" |
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return (word[-suffix_len-2:-suffix_len] == 'dr' or |
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(word[-suffix_len-1] == 't' and |
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word[-suffix_len-2:-suffix_len] != 'tt')) |
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def cond_t(word, suffix_len): |
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"""Return Lovins' condition T.""" |
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return (word[-suffix_len-1] in {'s', 't'} and |
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word[-suffix_len-2:-suffix_len] != 'ot') |
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def cond_u(word, suffix_len): |
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"""Return Lovins' condition U.""" |
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return word[-suffix_len-1] in {'l', 'm', 'n', 'r'} |
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def cond_v(word, suffix_len): |
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"""Return Lovins' condition V.""" |
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return word[-suffix_len-1] == 'c' |
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def cond_w(word, suffix_len): |
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"""Return Lovins' condition W.""" |
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return word[-suffix_len-1] not in {'s', 'u'} |
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def cond_x(word, suffix_len): |
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"""Return Lovins' condition X.""" |
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return (word[-suffix_len-1] in {'i', 'l'} or |
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(word[-suffix_len-3:-suffix_len] == 'u' and |
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word[-suffix_len-1] == 'e')) |
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def cond_y(word, suffix_len): |
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"""Return Lovins' condition Y.""" |
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return word[-suffix_len-2:-suffix_len] == 'in' |
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def cond_z(word, suffix_len): |
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"""Return Lovins' condition Z.""" |
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return word[-suffix_len-1] != 'f' |
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def cond_aa(word, suffix_len): |
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"""Return Lovins' condition AA.""" |
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return (word[-suffix_len-1] in {'d', 'f', 'l', 't'} or |
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word[-suffix_len-2:-suffix_len] in {'ph', 'th', 'er', 'or', |
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'es'}) |
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def cond_bb(word, suffix_len): |
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"""Return Lovins' condition BB.""" |
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return (len(word)-suffix_len >= 3 and |
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word[-suffix_len-3:-suffix_len] != 'met' and |
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word[-suffix_len-4:-suffix_len] != 'ryst') |
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def cond_cc(word, suffix_len): |
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"""Return Lovins' condition CC.""" |
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return word[-suffix_len-1] == 'l' |
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suffix = {'alistically': cond_b, 'arizability': None, |
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'izationally': cond_b, 'antialness': None, |
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'arisations': None, 'arizations': None, 'entialness': None, |
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'allically': cond_c, 'antaneous': None, 'antiality': None, |
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'arisation': None, 'arization': None, 'ationally': cond_b, |
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'ativeness': None, 'eableness': cond_e, 'entations': None, |
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'entiality': None, 'entialize': None, 'entiation': None, |
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'ionalness': None, 'istically': None, 'itousness': None, |
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'izability': None, 'izational': None, 'ableness': None, |
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'arizable': None, 'entation': None, 'entially': None, |
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'eousness': None, 'ibleness': None, 'icalness': None, |
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'ionalism': None, 'ionality': None, 'ionalize': None, |
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'iousness': None, 'izations': None, 'lessness': None, |
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'ability': None, 'aically': None, 'alistic': cond_b, |
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'alities': None, 'ariness': cond_e, 'aristic': None, |
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'arizing': None, 'ateness': None, 'atingly': None, |
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'ational': cond_b, 'atively': None, 'ativism': None, |
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'elihood': cond_e, 'encible': None, 'entally': None, |
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'entials': None, 'entiate': None, 'entness': None, |
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'fulness': None, 'ibility': None, 'icalism': None, |
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'icalist': None, 'icality': None, 'icalize': None, |
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'ication': cond_g, 'icianry': None, 'ination': None, |
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'ingness': None, 'ionally': None, 'isation': None, |
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'ishness': None, 'istical': None, 'iteness': None, |
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'iveness': None, 'ivistic': None, 'ivities': None, |
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'ization': cond_f, 'izement': None, 'oidally': None, |
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'ousness': None, 'aceous': None, 'acious': cond_b, |
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'action': cond_g, 'alness': None, 'ancial': None, |
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'ancies': None, 'ancing': cond_b, 'ariser': None, |
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'arized': None, 'arizer': None, 'atable': None, |
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'ations': cond_b, 'atives': None, 'eature': cond_z, |
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'efully': None, 'encies': None, 'encing': None, |
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'ential': None, 'enting': cond_c, 'entist': None, |
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'eously': None, 'ialist': None, 'iality': None, |
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'ialize': None, 'ically': None, 'icance': None, |
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'icians': None, 'icists': None, 'ifully': None, |
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'ionals': None, 'ionate': cond_d, 'ioning': None, |
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'ionist': None, 'iously': None, 'istics': None, |
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'izable': cond_e, 'lessly': None, 'nesses': None, |
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'oidism': None, 'acies': None, 'acity': None, |
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'aging': cond_b, 'aical': None, 'alist': None, |
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'alism': cond_b, 'ality': None, 'alize': None, |
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'allic': cond_bb, 'anced': cond_b, 'ances': cond_b, |
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'antic': cond_c, 'arial': None, 'aries': None, |
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'arily': None, 'arity': cond_b, 'arize': None, |
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'aroid': None, 'ately': None, 'ating': cond_i, |
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'ation': cond_b, 'ative': None, 'ators': None, |
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'atory': None, 'ature': cond_e, 'early': cond_y, |
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'ehood': None, 'eless': None, 'elity': None, |
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'ement': None, 'enced': None, 'ences': None, |
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'eness': cond_e, 'ening': cond_e, 'ental': None, |
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'ented': cond_c, 'ently': None, 'fully': None, |
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'ially': None, 'icant': None, 'ician': None, |
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'icide': None, 'icism': None, 'icist': None, |
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'icity': None, 'idine': cond_i, 'iedly': None, |
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'ihood': None, 'inate': None, 'iness': None, |
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'ingly': cond_b, 'inism': cond_j, 'inity': cond_cc, |
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'ional': None, 'ioned': None, 'ished': None, |
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'istic': None, 'ities': None, 'itous': None, |
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'ively': None, 'ivity': None, 'izers': cond_f, |
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'izing': cond_f, 'oidal': None, 'oides': None, |
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'otide': None, 'ously': None, 'able': None, 'ably': None, |
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'ages': cond_b, 'ally': cond_b, 'ance': cond_b, 'ancy': cond_b, |
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'ants': cond_b, 'aric': None, 'arly': cond_k, 'ated': cond_i, |
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'ates': None, 'atic': cond_b, 'ator': None, 'ealy': cond_y, |
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'edly': cond_e, 'eful': None, 'eity': None, 'ence': None, |
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'ency': None, 'ened': cond_e, 'enly': cond_e, 'eous': None, |
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'hood': None, 'ials': None, 'ians': None, 'ible': None, |
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'ibly': None, 'ical': None, 'ides': cond_l, 'iers': None, |
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'iful': None, 'ines': cond_m, 'ings': cond_n, 'ions': cond_b, |
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'ious': None, 'isms': cond_b, 'ists': None, 'itic': cond_h, |
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'ized': cond_f, 'izer': cond_f, 'less': None, 'lily': None, |
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'ness': None, 'ogen': None, 'ward': None, 'wise': None, |
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'ying': cond_b, 'yish': None, 'acy': None, 'age': cond_b, |
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'aic': None, 'als': cond_bb, 'ant': cond_b, 'ars': cond_o, |
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'ary': cond_f, 'ata': None, 'ate': None, 'eal': cond_y, |
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'ear': cond_y, 'ely': cond_e, 'ene': cond_e, 'ent': cond_c, |
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'ery': cond_e, 'ese': None, 'ful': None, 'ial': None, |
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'ian': None, 'ics': None, 'ide': cond_l, 'ied': None, |
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'ier': None, 'ies': cond_p, 'ily': None, 'ine': cond_m, |
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'ing': cond_n, 'ion': cond_q, 'ish': cond_c, 'ism': cond_b, |
|
277
|
|
|
'ist': None, 'ite': cond_aa, 'ity': None, 'ium': None, |
|
278
|
|
|
'ive': None, 'ize': cond_f, 'oid': None, 'one': cond_r, |
|
279
|
|
|
'ous': None, 'ae': None, 'al': cond_bb, 'ar': cond_x, |
|
280
|
|
|
'as': cond_b, 'ed': cond_e, 'en': cond_f, 'es': cond_e, |
|
281
|
|
|
'ia': None, 'ic': None, 'is': None, 'ly': cond_b, |
|
282
|
|
|
'on': cond_s, 'or': cond_t, 'um': cond_u, 'us': cond_v, |
|
283
|
|
|
'yl': cond_r, '\'s': None, 's\'': None, 'a': None, |
|
284
|
|
|
'e': None, 'i': None, 'o': None, 's': cond_w, 'y': cond_b} |
|
285
|
|
|
|
|
286
|
|
|
for suffix_len in range(11, 0, -1): |
|
287
|
|
|
ending = word[-suffix_len:] |
|
288
|
|
|
if (ending in suffix and |
|
289
|
|
|
len(word)-suffix_len >= 2 and |
|
290
|
|
|
(suffix[ending] is None or |
|
291
|
|
|
suffix[ending](word, suffix_len))): |
|
292
|
|
|
word = word[:-suffix_len] |
|
293
|
|
|
break |
|
294
|
|
|
|
|
295
|
|
|
def recode9(stem): |
|
296
|
|
|
"""Return Lovins' conditional recode rule 9.""" |
|
297
|
|
|
if stem[-3:-2] in {'a', 'i', 'o'}: |
|
298
|
|
|
return stem |
|
299
|
|
|
return stem[:-2]+'l' |
|
300
|
|
|
|
|
301
|
|
|
def recode24(stem): |
|
302
|
|
|
"""Return Lovins' conditional recode rule 24.""" |
|
303
|
|
|
if stem[-4:-3] == 's': |
|
304
|
|
|
return stem |
|
305
|
|
|
return stem[:-1]+'s' |
|
306
|
|
|
|
|
307
|
|
|
def recode28(stem): |
|
308
|
|
|
"""Return Lovins' conditional recode rule 28.""" |
|
309
|
|
|
if stem[-4:-3] in {'p', 't'}: |
|
310
|
|
|
return stem |
|
311
|
|
|
return stem[:-1]+'s' |
|
312
|
|
|
|
|
313
|
|
|
def recode30(stem): |
|
314
|
|
|
"""Return Lovins' conditional recode rule 30.""" |
|
315
|
|
|
if stem[-4:-3] == 'm': |
|
316
|
|
|
return stem |
|
317
|
|
|
return stem[:-1]+'s' |
|
318
|
|
|
|
|
319
|
|
|
def recode32(stem): |
|
320
|
|
|
"""Return Lovins' conditional recode rule 32.""" |
|
321
|
|
|
if stem[-3:-2] == 'n': |
|
322
|
|
|
return stem |
|
323
|
|
|
return stem[:-1]+'s' |
|
324
|
|
|
|
|
325
|
|
|
if word[-2:] in {'bb', 'dd', 'gg', 'll', 'mm', 'nn', 'pp', 'rr', 'ss', |
|
326
|
|
|
'tt'}: |
|
327
|
|
|
word = word[:-1] |
|
328
|
|
|
|
|
329
|
|
|
recode = (('iev', 'ief'), |
|
330
|
|
|
('uct', 'uc'), |
|
331
|
|
|
('umpt', 'um'), |
|
332
|
|
|
('rpt', 'rb'), |
|
333
|
|
|
('urs', 'ur'), |
|
334
|
|
|
('istr', 'ister'), |
|
335
|
|
|
('metr', 'meter'), |
|
336
|
|
|
('olv', 'olut'), |
|
337
|
|
|
('ul', recode9), |
|
338
|
|
|
('bex', 'bic'), |
|
339
|
|
|
('dex', 'dic'), |
|
340
|
|
|
('pex', 'pic'), |
|
341
|
|
|
('tex', 'tic'), |
|
342
|
|
|
('ax', 'ac'), |
|
343
|
|
|
('ex', 'ec'), |
|
344
|
|
|
('ix', 'ic'), |
|
345
|
|
|
('lux', 'luc'), |
|
346
|
|
|
('uad', 'uas'), |
|
347
|
|
|
('vad', 'vas'), |
|
348
|
|
|
('cid', 'cis'), |
|
349
|
|
|
('lid', 'lis'), |
|
350
|
|
|
('erid', 'eris'), |
|
351
|
|
|
('pand', 'pans'), |
|
352
|
|
|
('end', recode24), |
|
353
|
|
|
('ond', 'ons'), |
|
354
|
|
|
('lud', 'lus'), |
|
355
|
|
|
('rud', 'rus'), |
|
356
|
|
|
('her', recode28), |
|
357
|
|
|
('mit', 'mis'), |
|
358
|
|
|
('ent', recode30), |
|
359
|
|
|
('ert', 'ers'), |
|
360
|
|
|
('et', recode32), |
|
361
|
|
|
('yt', 'ys'), |
|
362
|
|
|
('yz', 'ys')) |
|
363
|
|
|
|
|
364
|
|
|
for ending, replacement in recode: |
|
365
|
|
|
if word.endswith(ending): |
|
366
|
|
|
if callable(replacement): |
|
367
|
|
|
word = replacement(word) |
|
368
|
|
|
else: |
|
369
|
|
|
word = word[:-len(ending)] + replacement |
|
370
|
|
|
|
|
371
|
|
|
return word |
|
372
|
|
|
|
|
373
|
|
|
|
|
374
|
|
|
def _m_degree(term, vowels): |
|
375
|
|
|
"""Return Porter helper function _m_degree value. |
|
376
|
|
|
|
|
377
|
|
|
m-degree is equal to the number of V to C transitions |
|
378
|
|
|
|
|
379
|
|
|
:param term: the word for which to calculate the m-degree |
|
380
|
|
|
:param vowels: the set of vowels in the language |
|
381
|
|
|
:returns: the m-degree as defined in the Porter stemmer definition |
|
382
|
|
|
""" |
|
383
|
|
|
mdeg = 0 |
|
384
|
|
|
last_was_vowel = False |
|
385
|
|
|
for letter in term: |
|
386
|
|
|
if letter in vowels: |
|
387
|
|
|
last_was_vowel = True |
|
388
|
|
|
else: |
|
389
|
|
|
if last_was_vowel: |
|
390
|
|
|
mdeg += 1 |
|
391
|
|
|
last_was_vowel = False |
|
392
|
|
|
return mdeg |
|
393
|
|
|
|
|
394
|
|
|
|
|
395
|
|
|
def _sb_has_vowel(term, vowels): |
|
396
|
|
|
"""Return Porter helper function _sb_has_vowel value. |
|
397
|
|
|
|
|
398
|
|
|
:param term: the word to scan for vowels |
|
399
|
|
|
:param vowels: the set of vowels in the language |
|
400
|
|
|
:returns: true iff a vowel exists in the term (as defined in the Porter |
|
401
|
|
|
stemmer definition) |
|
402
|
|
|
""" |
|
403
|
|
|
for letter in term: |
|
404
|
|
|
if letter in vowels: |
|
405
|
|
|
return True |
|
406
|
|
|
return False |
|
407
|
|
|
|
|
408
|
|
|
|
|
409
|
|
|
def _ends_in_doubled_cons(term, vowels): |
|
410
|
|
|
"""Return Porter helper function _ends_in_doubled_cons value. |
|
411
|
|
|
|
|
412
|
|
|
:param term: the word to check for a final doubled consonant |
|
413
|
|
|
:param vowels: the set of vowels in the language |
|
414
|
|
|
:returns: true iff the stem ends in a doubled consonant (as defined in the |
|
415
|
|
|
Porter stemmer definition) |
|
416
|
|
|
""" |
|
417
|
|
|
if len(term) > 1 and term[-1] not in vowels and term[-2] == term[-1]: |
|
418
|
|
|
return True |
|
419
|
|
|
return False |
|
420
|
|
|
|
|
421
|
|
|
|
|
422
|
|
|
def _ends_in_cvc(term, vowels): |
|
423
|
|
|
"""Return Porter helper function _ends_in_cvc value. |
|
424
|
|
|
|
|
425
|
|
|
:param term: the word to scan for cvc |
|
426
|
|
|
:param vowels: the set of vowels in the language |
|
427
|
|
|
:returns: true iff the stem ends in cvc (as defined in the Porter stemmer |
|
428
|
|
|
definition) |
|
429
|
|
|
""" |
|
430
|
|
|
if len(term) > 2 and (term[-1] not in vowels and |
|
431
|
|
|
term[-2] in vowels and |
|
432
|
|
|
term[-3] not in vowels and |
|
433
|
|
|
term[-1] not in tuple('wxY')): |
|
434
|
|
|
return True |
|
435
|
|
|
return False |
|
436
|
|
|
|
|
437
|
|
|
|
|
438
|
|
|
def porter(word, early_english=False): |
|
439
|
|
|
"""Return Porter stem. |
|
440
|
|
|
|
|
441
|
|
|
The Porter stemmer is defined at: |
|
442
|
|
|
http://snowball.tartarus.org/algorithms/porter/stemmer.html |
|
443
|
|
|
|
|
444
|
|
|
:param word: the word to calculate the stem of |
|
445
|
|
|
:param early_english: set to True in order to remove -eth & -est (2nd & 3rd |
|
446
|
|
|
person singular verbal agreement suffixes) |
|
447
|
|
|
:returns: word stem |
|
448
|
|
|
:rtype: str |
|
449
|
|
|
|
|
450
|
|
|
>>> porter('reading') |
|
451
|
|
|
'read' |
|
452
|
|
|
>>> porter('suspension') |
|
453
|
|
|
'suspens' |
|
454
|
|
|
>>> porter('elusiveness') |
|
455
|
|
|
'elus' |
|
456
|
|
|
|
|
457
|
|
|
>>> porter('eateth', early_english=True) |
|
458
|
|
|
'eat' |
|
459
|
|
|
""" |
|
460
|
|
|
# pylint: disable=too-many-branches |
|
461
|
|
|
|
|
462
|
|
|
# lowercase, normalize, and compose |
|
463
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
464
|
|
|
|
|
465
|
|
|
# Return word if stem is shorter than 2 |
|
466
|
|
|
if len(word) < 3: |
|
467
|
|
|
return word |
|
468
|
|
|
|
|
469
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y'} |
|
470
|
|
|
# Re-map consonantal y to Y (Y will be C, y will be V) |
|
471
|
|
|
if word[0] == 'y': |
|
472
|
|
|
word = 'Y' + word[1:] |
|
473
|
|
|
for i in range(1, len(word)): |
|
474
|
|
|
if word[i] == 'y' and word[i-1] in _vowels: |
|
475
|
|
|
word = word[:i] + 'Y' + word[i+1:] |
|
476
|
|
|
|
|
477
|
|
|
# Step 1a |
|
478
|
|
|
if word[-1] == 's': |
|
479
|
|
|
if word[-4:] == 'sses': |
|
480
|
|
|
word = word[:-2] |
|
481
|
|
|
elif word[-3:] == 'ies': |
|
482
|
|
|
word = word[:-2] |
|
483
|
|
|
elif word[-2:] == 'ss': |
|
484
|
|
|
pass |
|
485
|
|
|
else: |
|
486
|
|
|
word = word[:-1] |
|
487
|
|
|
|
|
488
|
|
|
# Step 1b |
|
489
|
|
|
step1b_flag = False |
|
490
|
|
|
if word[-3:] == 'eed': |
|
491
|
|
|
if _m_degree(word[:-3], _vowels) > 0: |
|
492
|
|
|
word = word[:-1] |
|
493
|
|
|
elif word[-2:] == 'ed': |
|
494
|
|
|
if _sb_has_vowel(word[:-2], _vowels): |
|
495
|
|
|
word = word[:-2] |
|
496
|
|
|
step1b_flag = True |
|
497
|
|
|
elif word[-3:] == 'ing': |
|
498
|
|
|
if _sb_has_vowel(word[:-3], _vowels): |
|
499
|
|
|
word = word[:-3] |
|
500
|
|
|
step1b_flag = True |
|
501
|
|
|
elif early_english: |
|
502
|
|
|
if word[-3:] == 'est': |
|
503
|
|
|
if _sb_has_vowel(word[:-3], _vowels): |
|
504
|
|
|
word = word[:-3] |
|
505
|
|
|
step1b_flag = True |
|
506
|
|
|
elif word[-3:] == 'eth': |
|
507
|
|
|
if _sb_has_vowel(word[:-3], _vowels): |
|
508
|
|
|
word = word[:-3] |
|
509
|
|
|
step1b_flag = True |
|
510
|
|
|
|
|
511
|
|
|
if step1b_flag: |
|
512
|
|
|
if word[-2:] in {'at', 'bl', 'iz'}: |
|
513
|
|
|
word += 'e' |
|
514
|
|
|
elif (_ends_in_doubled_cons(word, _vowels) and |
|
515
|
|
|
word[-1] not in {'l', 's', 'z'}): |
|
516
|
|
|
word = word[:-1] |
|
517
|
|
|
elif _m_degree(word, _vowels) == 1 and _ends_in_cvc(word, _vowels): |
|
518
|
|
|
word += 'e' |
|
519
|
|
|
|
|
520
|
|
|
# Step 1c |
|
521
|
|
|
if word[-1] in {'Y', 'y'} and _sb_has_vowel(word[:-1], _vowels): |
|
522
|
|
|
word = word[:-1] + 'i' |
|
523
|
|
|
|
|
524
|
|
|
# Step 2 |
|
525
|
|
|
if len(word) > 1: |
|
526
|
|
|
if word[-2] == 'a': |
|
527
|
|
|
if word[-7:] == 'ational': |
|
528
|
|
|
if _m_degree(word[:-7], _vowels) > 0: |
|
529
|
|
|
word = word[:-5] + 'e' |
|
530
|
|
|
elif word[-6:] == 'tional': |
|
531
|
|
|
if _m_degree(word[:-6], _vowels) > 0: |
|
532
|
|
|
word = word[:-2] |
|
533
|
|
|
elif word[-2] == 'c': |
|
534
|
|
|
if word[-4:] in {'enci', 'anci'}: |
|
535
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
536
|
|
|
word = word[:-1] + 'e' |
|
537
|
|
|
elif word[-2] == 'e': |
|
538
|
|
|
if word[-4:] == 'izer': |
|
539
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
540
|
|
|
word = word[:-1] |
|
541
|
|
|
elif word[-2] == 'g': |
|
542
|
|
|
if word[-4:] == 'logi': |
|
543
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
544
|
|
|
word = word[:-1] |
|
545
|
|
|
elif word[-2] == 'l': |
|
546
|
|
|
if word[-3:] == 'bli': |
|
547
|
|
|
if _m_degree(word[:-3], _vowels) > 0: |
|
548
|
|
|
word = word[:-1] + 'e' |
|
549
|
|
|
elif word[-4:] == 'alli': |
|
550
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
551
|
|
|
word = word[:-2] |
|
552
|
|
|
elif word[-5:] == 'entli': |
|
553
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
554
|
|
|
word = word[:-2] |
|
555
|
|
|
elif word[-3:] == 'eli': |
|
556
|
|
|
if _m_degree(word[:-3], _vowels) > 0: |
|
557
|
|
|
word = word[:-2] |
|
558
|
|
|
elif word[-5:] == 'ousli': |
|
559
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
560
|
|
|
word = word[:-2] |
|
561
|
|
|
elif word[-2] == 'o': |
|
562
|
|
|
if word[-7:] == 'ization': |
|
563
|
|
|
if _m_degree(word[:-7], _vowels) > 0: |
|
564
|
|
|
word = word[:-5] + 'e' |
|
565
|
|
|
elif word[-5:] == 'ation': |
|
566
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
567
|
|
|
word = word[:-3] + 'e' |
|
568
|
|
|
elif word[-4:] == 'ator': |
|
569
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
570
|
|
|
word = word[:-2] + 'e' |
|
571
|
|
|
elif word[-2] == 's': |
|
572
|
|
|
if word[-5:] == 'alism': |
|
573
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
574
|
|
|
word = word[:-3] |
|
575
|
|
|
elif word[-7:] in {'iveness', 'fulness', 'ousness'}: |
|
576
|
|
|
if _m_degree(word[:-7], _vowels) > 0: |
|
577
|
|
|
word = word[:-4] |
|
578
|
|
|
elif word[-2] == 't': |
|
579
|
|
|
if word[-5:] == 'aliti': |
|
580
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
581
|
|
|
word = word[:-3] |
|
582
|
|
|
elif word[-5:] == 'iviti': |
|
583
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
584
|
|
|
word = word[:-3] + 'e' |
|
585
|
|
|
elif word[-6:] == 'biliti': |
|
586
|
|
|
if _m_degree(word[:-6], _vowels) > 0: |
|
587
|
|
|
word = word[:-5] + 'le' |
|
588
|
|
|
|
|
589
|
|
|
# Step 3 |
|
590
|
|
|
if word[-5:] == 'icate': |
|
591
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
592
|
|
|
word = word[:-3] |
|
593
|
|
|
elif word[-5:] == 'ative': |
|
594
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
595
|
|
|
word = word[:-5] |
|
596
|
|
|
elif word[-5:] in {'alize', 'iciti'}: |
|
597
|
|
|
if _m_degree(word[:-5], _vowels) > 0: |
|
598
|
|
|
word = word[:-3] |
|
599
|
|
|
elif word[-4:] == 'ical': |
|
600
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
601
|
|
|
word = word[:-2] |
|
602
|
|
|
elif word[-3:] == 'ful': |
|
603
|
|
|
if _m_degree(word[:-3], _vowels) > 0: |
|
604
|
|
|
word = word[:-3] |
|
605
|
|
|
elif word[-4:] == 'ness': |
|
606
|
|
|
if _m_degree(word[:-4], _vowels) > 0: |
|
607
|
|
|
word = word[:-4] |
|
608
|
|
|
|
|
609
|
|
|
# Step 4 |
|
610
|
|
|
if word[-2:] == 'al': |
|
611
|
|
|
if _m_degree(word[:-2], _vowels) > 1: |
|
612
|
|
|
word = word[:-2] |
|
613
|
|
|
elif word[-4:] == 'ance': |
|
614
|
|
|
if _m_degree(word[:-4], _vowels) > 1: |
|
615
|
|
|
word = word[:-4] |
|
616
|
|
|
elif word[-4:] == 'ence': |
|
617
|
|
|
if _m_degree(word[:-4], _vowels) > 1: |
|
618
|
|
|
word = word[:-4] |
|
619
|
|
|
elif word[-2:] == 'er': |
|
620
|
|
|
if _m_degree(word[:-2], _vowels) > 1: |
|
621
|
|
|
word = word[:-2] |
|
622
|
|
|
elif word[-2:] == 'ic': |
|
623
|
|
|
if _m_degree(word[:-2], _vowels) > 1: |
|
624
|
|
|
word = word[:-2] |
|
625
|
|
|
elif word[-4:] == 'able': |
|
626
|
|
|
if _m_degree(word[:-4], _vowels) > 1: |
|
627
|
|
|
word = word[:-4] |
|
628
|
|
|
elif word[-4:] == 'ible': |
|
629
|
|
|
if _m_degree(word[:-4], _vowels) > 1: |
|
630
|
|
|
word = word[:-4] |
|
631
|
|
|
elif word[-3:] == 'ant': |
|
632
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
633
|
|
|
word = word[:-3] |
|
634
|
|
|
elif word[-5:] == 'ement': |
|
635
|
|
|
if _m_degree(word[:-5], _vowels) > 1: |
|
636
|
|
|
word = word[:-5] |
|
637
|
|
|
elif word[-4:] == 'ment': |
|
638
|
|
|
if _m_degree(word[:-4], _vowels) > 1: |
|
639
|
|
|
word = word[:-4] |
|
640
|
|
|
elif word[-3:] == 'ent': |
|
641
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
642
|
|
|
word = word[:-3] |
|
643
|
|
|
elif word[-4:] in {'sion', 'tion'}: |
|
644
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
645
|
|
|
word = word[:-3] |
|
646
|
|
|
elif word[-2:] == 'ou': |
|
647
|
|
|
if _m_degree(word[:-2], _vowels) > 1: |
|
648
|
|
|
word = word[:-2] |
|
649
|
|
|
elif word[-3:] == 'ism': |
|
650
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
651
|
|
|
word = word[:-3] |
|
652
|
|
|
elif word[-3:] == 'ate': |
|
653
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
654
|
|
|
word = word[:-3] |
|
655
|
|
|
elif word[-3:] == 'iti': |
|
656
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
657
|
|
|
word = word[:-3] |
|
658
|
|
|
elif word[-3:] == 'ous': |
|
659
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
660
|
|
|
word = word[:-3] |
|
661
|
|
|
elif word[-3:] == 'ive': |
|
662
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
663
|
|
|
word = word[:-3] |
|
664
|
|
|
elif word[-3:] == 'ize': |
|
665
|
|
|
if _m_degree(word[:-3], _vowels) > 1: |
|
666
|
|
|
word = word[:-3] |
|
667
|
|
|
|
|
668
|
|
|
# Step 5a |
|
669
|
|
|
if word[-1] == 'e': |
|
670
|
|
|
if _m_degree(word[:-1], _vowels) > 1: |
|
671
|
|
|
word = word[:-1] |
|
672
|
|
|
elif (_m_degree(word[:-1], _vowels) == 1 and |
|
673
|
|
|
not _ends_in_cvc(word[:-1], _vowels)): |
|
674
|
|
|
word = word[:-1] |
|
675
|
|
|
|
|
676
|
|
|
# Step 5b |
|
677
|
|
|
if word[-2:] == 'll' and _m_degree(word, _vowels) > 1: |
|
678
|
|
|
word = word[:-1] |
|
679
|
|
|
|
|
680
|
|
|
# Change 'Y' back to 'y' if it survived stemming |
|
681
|
|
|
for i in range(len(word)): |
|
682
|
|
|
if word[i] == 'Y': |
|
683
|
|
|
word = word[:i] + 'y' + word[i+1:] |
|
684
|
|
|
|
|
685
|
|
|
return word |
|
686
|
|
|
|
|
687
|
|
|
|
|
688
|
|
|
def _sb_r1(term, vowels, r1_prefixes=None): |
|
689
|
|
|
"""Return the R1 region, as defined in the Porter2 specification.""" |
|
690
|
|
|
vowel_found = False |
|
691
|
|
|
if hasattr(r1_prefixes, '__iter__'): |
|
692
|
|
|
for prefix in r1_prefixes: |
|
693
|
|
|
if term[:len(prefix)] == prefix: |
|
694
|
|
|
return len(prefix) |
|
695
|
|
|
|
|
696
|
|
|
for i in range(len(term)): |
|
697
|
|
|
if not vowel_found and term[i] in vowels: |
|
698
|
|
|
vowel_found = True |
|
699
|
|
|
elif vowel_found and term[i] not in vowels: |
|
700
|
|
|
return i + 1 |
|
701
|
|
|
return len(term) |
|
702
|
|
|
|
|
703
|
|
|
|
|
704
|
|
|
def _sb_r2(term, vowels, r1_prefixes=None): |
|
705
|
|
|
"""Return the R2 region, as defined in the Porter2 specification.""" |
|
706
|
|
|
r1_start = _sb_r1(term, vowels, r1_prefixes) |
|
707
|
|
|
return r1_start + _sb_r1(term[r1_start:], vowels) |
|
708
|
|
|
|
|
709
|
|
|
|
|
710
|
|
|
def _sb_ends_in_short_syllable(term, vowels, codanonvowels): |
|
711
|
|
|
"""Return True iff term ends in a short syllable. |
|
712
|
|
|
|
|
713
|
|
|
(...according to the Porter2 specification.) |
|
714
|
|
|
|
|
715
|
|
|
NB: This is akin to the CVC test from the Porter stemmer. The description |
|
716
|
|
|
is unfortunately poor/ambiguous. |
|
717
|
|
|
""" |
|
718
|
|
|
if not term: |
|
719
|
|
|
return False |
|
720
|
|
|
if len(term) == 2: |
|
721
|
|
|
if term[-2] in vowels and term[-1] not in vowels: |
|
722
|
|
|
return True |
|
723
|
|
|
elif len(term) >= 3: |
|
724
|
|
|
if ((term[-3] not in vowels and term[-2] in vowels and |
|
725
|
|
|
term[-1] in codanonvowels)): |
|
726
|
|
|
return True |
|
727
|
|
|
return False |
|
728
|
|
|
|
|
729
|
|
|
|
|
730
|
|
|
def _sb_short_word(term, vowels, codanonvowels, r1_prefixes=None): |
|
731
|
|
|
"""Return True iff term is a short word. |
|
732
|
|
|
|
|
733
|
|
|
(...according to the Porter2 specification.) |
|
734
|
|
|
""" |
|
735
|
|
|
if ((_sb_r1(term, vowels, r1_prefixes) == len(term) and |
|
736
|
|
|
_sb_ends_in_short_syllable(term, vowels, codanonvowels))): |
|
737
|
|
|
return True |
|
738
|
|
|
return False |
|
739
|
|
|
|
|
740
|
|
|
|
|
741
|
|
|
def porter2(word, early_english=False): |
|
742
|
|
|
"""Return the Porter2 (Snowball English) stem. |
|
743
|
|
|
|
|
744
|
|
|
The Porter2 (Snowball English) stemmer is defined at: |
|
745
|
|
|
http://snowball.tartarus.org/algorithms/english/stemmer.html |
|
746
|
|
|
|
|
747
|
|
|
:param word: the word to calculate the stem of |
|
748
|
|
|
:param early_english: set to True in order to remove -eth & -est (2nd & 3rd |
|
749
|
|
|
person singular verbal agreement suffixes) |
|
750
|
|
|
:returns: word stem |
|
751
|
|
|
:rtype: str |
|
752
|
|
|
|
|
753
|
|
|
>>> porter2('reading') |
|
754
|
|
|
'read' |
|
755
|
|
|
>>> porter2('suspension') |
|
756
|
|
|
'suspens' |
|
757
|
|
|
>>> porter2('elusiveness') |
|
758
|
|
|
'elus' |
|
759
|
|
|
|
|
760
|
|
|
>>> porter2('eateth', early_english=True) |
|
761
|
|
|
'eat' |
|
762
|
|
|
""" |
|
763
|
|
|
# pylint: disable=too-many-branches |
|
764
|
|
|
# pylint: disable=too-many-return-statements |
|
765
|
|
|
|
|
766
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y'} |
|
767
|
|
|
_codanonvowels = {"'", 'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', |
|
768
|
|
|
'n', 'p', 'q', 'r', 's', 't', 'v', 'z'} |
|
769
|
|
|
_doubles = {'bb', 'dd', 'ff', 'gg', 'mm', 'nn', 'pp', 'rr', 'tt'} |
|
770
|
|
|
_li = {'c', 'd', 'e', 'g', 'h', 'k', 'm', 'n', 'r', 't'} |
|
771
|
|
|
|
|
772
|
|
|
# R1 prefixes should be in order from longest to shortest to prevent |
|
773
|
|
|
# masking |
|
774
|
|
|
_r1_prefixes = ('commun', 'gener', 'arsen') |
|
775
|
|
|
_exception1dict = { # special changes: |
|
776
|
|
|
'skis': 'ski', 'skies': 'sky', 'dying': 'die', |
|
777
|
|
|
'lying': 'lie', 'tying': 'tie', |
|
778
|
|
|
# special -LY cases: |
|
779
|
|
|
'idly': 'idl', 'gently': 'gentl', 'ugly': 'ugli', |
|
780
|
|
|
'early': 'earli', 'only': 'onli', 'singly': 'singl'} |
|
781
|
|
|
_exception1set = {'sky', 'news', 'howe', 'atlas', 'cosmos', 'bias', |
|
782
|
|
|
'andes'} |
|
783
|
|
|
_exception2set = {'inning', 'outing', 'canning', 'herring', 'earring', |
|
784
|
|
|
'proceed', 'exceed', 'succeed'} |
|
785
|
|
|
|
|
786
|
|
|
# lowercase, normalize, and compose |
|
787
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
788
|
|
|
# replace apostrophe-like characters with U+0027, per |
|
789
|
|
|
# http://snowball.tartarus.org/texts/apostrophe.html |
|
790
|
|
|
word = word.replace('’', '\'') |
|
791
|
|
|
word = word.replace('’', '\'') |
|
792
|
|
|
|
|
793
|
|
|
# Exceptions 1 |
|
794
|
|
|
if word in _exception1dict: |
|
795
|
|
|
return _exception1dict[word] |
|
796
|
|
|
elif word in _exception1set: |
|
797
|
|
|
return word |
|
798
|
|
|
|
|
799
|
|
|
# Return word if stem is shorter than 3 |
|
800
|
|
|
if len(word) < 3: |
|
801
|
|
|
return word |
|
802
|
|
|
|
|
803
|
|
|
# Remove initial ', if present. |
|
804
|
|
|
while word and word[0] == '\'': |
|
805
|
|
|
word = word[1:] |
|
806
|
|
|
# Return word if stem is shorter than 2 |
|
807
|
|
|
if len(word) < 2: |
|
808
|
|
|
return word |
|
809
|
|
|
|
|
810
|
|
|
# Re-map vocalic Y to y (Y will be C, y will be V) |
|
811
|
|
|
if word[0] == 'y': |
|
812
|
|
|
word = 'Y' + word[1:] |
|
813
|
|
|
for i in range(1, len(word)): |
|
814
|
|
|
if word[i] == 'y' and word[i-1] in _vowels: |
|
815
|
|
|
word = word[:i] + 'Y' + word[i+1:] |
|
816
|
|
|
|
|
817
|
|
|
r1_start = _sb_r1(word, _vowels, _r1_prefixes) |
|
818
|
|
|
r2_start = _sb_r2(word, _vowels, _r1_prefixes) |
|
819
|
|
|
|
|
820
|
|
|
# Step 0 |
|
821
|
|
|
if word[-3:] == '\'s\'': |
|
822
|
|
|
word = word[:-3] |
|
823
|
|
|
elif word[-2:] == '\'s': |
|
824
|
|
|
word = word[:-2] |
|
825
|
|
|
elif word[-1:] == '\'': |
|
826
|
|
|
word = word[:-1] |
|
827
|
|
|
# Return word if stem is shorter than 2 |
|
828
|
|
|
if len(word) < 3: |
|
829
|
|
|
return word |
|
830
|
|
|
|
|
831
|
|
|
# Step 1a |
|
832
|
|
|
if word[-4:] == 'sses': |
|
833
|
|
|
word = word[:-2] |
|
834
|
|
|
elif word[-3:] in {'ied', 'ies'}: |
|
835
|
|
|
if len(word) > 4: |
|
836
|
|
|
word = word[:-2] |
|
837
|
|
|
else: |
|
838
|
|
|
word = word[:-1] |
|
839
|
|
|
elif word[-2:] in {'us', 'ss'}: |
|
840
|
|
|
pass |
|
841
|
|
|
elif word[-1] == 's': |
|
842
|
|
|
if _sb_has_vowel(word[:-2], _vowels): |
|
843
|
|
|
word = word[:-1] |
|
844
|
|
|
|
|
845
|
|
|
# Exceptions 2 |
|
846
|
|
|
if word in _exception2set: |
|
847
|
|
|
return word |
|
848
|
|
|
|
|
849
|
|
|
# Step 1b |
|
850
|
|
|
step1b_flag = False |
|
851
|
|
|
if word[-5:] == 'eedly': |
|
852
|
|
|
if len(word[r1_start:]) >= 5: |
|
853
|
|
|
word = word[:-3] |
|
854
|
|
|
elif word[-5:] == 'ingly': |
|
855
|
|
|
if _sb_has_vowel(word[:-5], _vowels): |
|
856
|
|
|
word = word[:-5] |
|
857
|
|
|
step1b_flag = True |
|
858
|
|
|
elif word[-4:] == 'edly': |
|
859
|
|
|
if _sb_has_vowel(word[:-4], _vowels): |
|
860
|
|
|
word = word[:-4] |
|
861
|
|
|
step1b_flag = True |
|
862
|
|
|
elif word[-3:] == 'eed': |
|
863
|
|
|
if len(word[r1_start:]) >= 3: |
|
864
|
|
|
word = word[:-1] |
|
865
|
|
|
elif word[-3:] == 'ing': |
|
866
|
|
|
if _sb_has_vowel(word[:-3], _vowels): |
|
867
|
|
|
word = word[:-3] |
|
868
|
|
|
step1b_flag = True |
|
869
|
|
|
elif word[-2:] == 'ed': |
|
870
|
|
|
if _sb_has_vowel(word[:-2], _vowels): |
|
871
|
|
|
word = word[:-2] |
|
872
|
|
|
step1b_flag = True |
|
873
|
|
|
elif early_english: |
|
874
|
|
|
if word[-3:] == 'est': |
|
875
|
|
|
if _sb_has_vowel(word[:-3], _vowels): |
|
876
|
|
|
word = word[:-3] |
|
877
|
|
|
step1b_flag = True |
|
878
|
|
|
elif word[-3:] == 'eth': |
|
879
|
|
|
if _sb_has_vowel(word[:-3], _vowels): |
|
880
|
|
|
word = word[:-3] |
|
881
|
|
|
step1b_flag = True |
|
882
|
|
|
|
|
883
|
|
|
if step1b_flag: |
|
884
|
|
|
if word[-2:] in {'at', 'bl', 'iz'}: |
|
885
|
|
|
word += 'e' |
|
886
|
|
|
elif word[-2:] in _doubles: |
|
887
|
|
|
word = word[:-1] |
|
888
|
|
|
elif _sb_short_word(word, _vowels, _codanonvowels, _r1_prefixes): |
|
889
|
|
|
word += 'e' |
|
890
|
|
|
|
|
891
|
|
|
# Step 1c |
|
892
|
|
|
if ((len(word) > 2 and word[-1] in {'Y', 'y'} and |
|
893
|
|
|
word[-2] not in _vowels)): |
|
894
|
|
|
word = word[:-1] + 'i' |
|
895
|
|
|
|
|
896
|
|
|
# Step 2 |
|
897
|
|
|
if word[-2] == 'a': |
|
898
|
|
|
if word[-7:] == 'ational': |
|
899
|
|
|
if len(word[r1_start:]) >= 7: |
|
900
|
|
|
word = word[:-5] + 'e' |
|
901
|
|
|
elif word[-6:] == 'tional': |
|
902
|
|
|
if len(word[r1_start:]) >= 6: |
|
903
|
|
|
word = word[:-2] |
|
904
|
|
|
elif word[-2] == 'c': |
|
905
|
|
|
if word[-4:] in {'enci', 'anci'}: |
|
906
|
|
|
if len(word[r1_start:]) >= 4: |
|
907
|
|
|
word = word[:-1] + 'e' |
|
908
|
|
|
elif word[-2] == 'e': |
|
909
|
|
|
if word[-4:] == 'izer': |
|
910
|
|
|
if len(word[r1_start:]) >= 4: |
|
911
|
|
|
word = word[:-1] |
|
912
|
|
|
elif word[-2] == 'g': |
|
913
|
|
|
if word[-3:] == 'ogi': |
|
914
|
|
|
if ((r1_start >= 1 and len(word[r1_start:]) >= 3 and |
|
915
|
|
|
word[-4] == 'l')): |
|
916
|
|
|
word = word[:-1] |
|
917
|
|
|
elif word[-2] == 'l': |
|
918
|
|
|
if word[-6:] == 'lessli': |
|
919
|
|
|
if len(word[r1_start:]) >= 6: |
|
920
|
|
|
word = word[:-2] |
|
921
|
|
|
elif word[-5:] in {'entli', 'fulli', 'ousli'}: |
|
922
|
|
|
if len(word[r1_start:]) >= 5: |
|
923
|
|
|
word = word[:-2] |
|
924
|
|
|
elif word[-4:] == 'abli': |
|
925
|
|
|
if len(word[r1_start:]) >= 4: |
|
926
|
|
|
word = word[:-1] + 'e' |
|
927
|
|
|
elif word[-4:] == 'alli': |
|
928
|
|
|
if len(word[r1_start:]) >= 4: |
|
929
|
|
|
word = word[:-2] |
|
930
|
|
|
elif word[-3:] == 'bli': |
|
931
|
|
|
if len(word[r1_start:]) >= 3: |
|
932
|
|
|
word = word[:-1] + 'e' |
|
933
|
|
|
elif word[-2:] == 'li': |
|
934
|
|
|
if ((r1_start >= 1 and len(word[r1_start:]) >= 2 and |
|
935
|
|
|
word[-3] in _li)): |
|
936
|
|
|
word = word[:-2] |
|
937
|
|
|
elif word[-2] == 'o': |
|
938
|
|
|
if word[-7:] == 'ization': |
|
939
|
|
|
if len(word[r1_start:]) >= 7: |
|
940
|
|
|
word = word[:-5] + 'e' |
|
941
|
|
|
elif word[-5:] == 'ation': |
|
942
|
|
|
if len(word[r1_start:]) >= 5: |
|
943
|
|
|
word = word[:-3] + 'e' |
|
944
|
|
|
elif word[-4:] == 'ator': |
|
945
|
|
|
if len(word[r1_start:]) >= 4: |
|
946
|
|
|
word = word[:-2] + 'e' |
|
947
|
|
|
elif word[-2] == 's': |
|
948
|
|
|
if word[-7:] in {'fulness', 'ousness', 'iveness'}: |
|
949
|
|
|
if len(word[r1_start:]) >= 7: |
|
950
|
|
|
word = word[:-4] |
|
951
|
|
|
elif word[-5:] == 'alism': |
|
952
|
|
|
if len(word[r1_start:]) >= 5: |
|
953
|
|
|
word = word[:-3] |
|
954
|
|
|
elif word[-2] == 't': |
|
955
|
|
|
if word[-6:] == 'biliti': |
|
956
|
|
|
if len(word[r1_start:]) >= 6: |
|
957
|
|
|
word = word[:-5] + 'le' |
|
958
|
|
|
elif word[-5:] == 'aliti': |
|
959
|
|
|
if len(word[r1_start:]) >= 5: |
|
960
|
|
|
word = word[:-3] |
|
961
|
|
|
elif word[-5:] == 'iviti': |
|
962
|
|
|
if len(word[r1_start:]) >= 5: |
|
963
|
|
|
word = word[:-3] + 'e' |
|
964
|
|
|
|
|
965
|
|
|
# Step 3 |
|
966
|
|
|
if word[-7:] == 'ational': |
|
967
|
|
|
if len(word[r1_start:]) >= 7: |
|
968
|
|
|
word = word[:-5] + 'e' |
|
969
|
|
|
elif word[-6:] == 'tional': |
|
970
|
|
|
if len(word[r1_start:]) >= 6: |
|
971
|
|
|
word = word[:-2] |
|
972
|
|
|
elif word[-5:] in {'alize', 'icate', 'iciti'}: |
|
973
|
|
|
if len(word[r1_start:]) >= 5: |
|
974
|
|
|
word = word[:-3] |
|
975
|
|
|
elif word[-5:] == 'ative': |
|
976
|
|
|
if len(word[r2_start:]) >= 5: |
|
977
|
|
|
word = word[:-5] |
|
978
|
|
|
elif word[-4:] == 'ical': |
|
979
|
|
|
if len(word[r1_start:]) >= 4: |
|
980
|
|
|
word = word[:-2] |
|
981
|
|
|
elif word[-4:] == 'ness': |
|
982
|
|
|
if len(word[r1_start:]) >= 4: |
|
983
|
|
|
word = word[:-4] |
|
984
|
|
|
elif word[-3:] == 'ful': |
|
985
|
|
|
if len(word[r1_start:]) >= 3: |
|
986
|
|
|
word = word[:-3] |
|
987
|
|
|
|
|
988
|
|
|
# Step 4 |
|
989
|
|
|
for suffix in ('ement', 'ance', 'ence', 'able', 'ible', 'ment', 'ant', |
|
990
|
|
|
'ent', 'ism', 'ate', 'iti', 'ous', 'ive', 'ize', 'al', 'er', |
|
991
|
|
|
'ic'): |
|
992
|
|
|
if word[-len(suffix):] == suffix: |
|
993
|
|
|
if len(word[r2_start:]) >= len(suffix): |
|
994
|
|
|
word = word[:-len(suffix)] |
|
995
|
|
|
break |
|
996
|
|
|
else: |
|
997
|
|
|
if word[-3:] == 'ion': |
|
998
|
|
|
if ((len(word[r2_start:]) >= 3 and len(word) >= 4 and |
|
999
|
|
|
word[-4] in tuple('st'))): |
|
1000
|
|
|
word = word[:-3] |
|
1001
|
|
|
|
|
1002
|
|
|
# Step 5 |
|
1003
|
|
|
if word[-1] == 'e': |
|
1004
|
|
|
if (len(word[r2_start:]) >= 1 or |
|
1005
|
|
|
(len(word[r1_start:]) >= 1 and |
|
1006
|
|
|
not _sb_ends_in_short_syllable(word[:-1], _vowels, |
|
1007
|
|
|
_codanonvowels))): |
|
1008
|
|
|
word = word[:-1] |
|
1009
|
|
|
elif word[-1] == 'l': |
|
1010
|
|
|
if len(word[r2_start:]) >= 1 and word[-2] == 'l': |
|
1011
|
|
|
word = word[:-1] |
|
1012
|
|
|
|
|
1013
|
|
|
# Change 'Y' back to 'y' if it survived stemming |
|
1014
|
|
|
for i in range(0, len(word)): |
|
1015
|
|
|
if word[i] == 'Y': |
|
1016
|
|
|
word = word[:i] + 'y' + word[i+1:] |
|
1017
|
|
|
|
|
1018
|
|
|
return word |
|
1019
|
|
|
|
|
1020
|
|
|
|
|
1021
|
|
|
def sb_german(word, alternate_vowels=False): |
|
1022
|
|
|
"""Return Snowball German stem. |
|
1023
|
|
|
|
|
1024
|
|
|
The Snowball German stemmer is defined at: |
|
1025
|
|
|
http://snowball.tartarus.org/algorithms/german/stemmer.html |
|
1026
|
|
|
|
|
1027
|
|
|
:param word: the word to calculate the stem of |
|
1028
|
|
|
:param alternate_vowels: composes ae as ä, oe as ö, and ue as ü before |
|
1029
|
|
|
running the algorithm |
|
1030
|
|
|
:returns: word stem |
|
1031
|
|
|
:rtype: str |
|
1032
|
|
|
|
|
1033
|
|
|
>>> sb_german('lesen') |
|
1034
|
|
|
'les' |
|
1035
|
|
|
>>> sb_german('graues') |
|
1036
|
|
|
'grau' |
|
1037
|
|
|
>>> sb_german('buchstabieren') |
|
1038
|
|
|
'buchstabi' |
|
1039
|
|
|
""" |
|
1040
|
|
|
# pylint: disable=too-many-branches |
|
1041
|
|
|
|
|
1042
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y', 'ä', 'ö', 'ü'} |
|
1043
|
|
|
_s_endings = {'b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 'r', 't'} |
|
1044
|
|
|
_st_endings = {'b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 't'} |
|
1045
|
|
|
|
|
1046
|
|
|
# lowercase, normalize, and compose |
|
1047
|
|
|
word = unicodedata.normalize('NFC', word.lower()) |
|
1048
|
|
|
word = word.replace('ß', 'ss') |
|
1049
|
|
|
|
|
1050
|
|
|
if len(word) > 2: |
|
1051
|
|
|
for i in range(2, len(word)): |
|
1052
|
|
|
if word[i] in _vowels and word[i-2] in _vowels: |
|
1053
|
|
|
if word[i-1] == 'u': |
|
1054
|
|
|
word = word[:i-1] + 'U' + word[i:] |
|
1055
|
|
|
elif word[i-1] == 'y': |
|
1056
|
|
|
word = word[:i-1] + 'Y' + word[i:] |
|
1057
|
|
|
|
|
1058
|
|
|
if alternate_vowels: |
|
1059
|
|
|
word = word.replace('ae', 'ä') |
|
1060
|
|
|
word = word.replace('oe', 'ö') |
|
1061
|
|
|
word = word.replace('que', 'Q') |
|
1062
|
|
|
word = word.replace('ue', 'ü') |
|
1063
|
|
|
word = word.replace('Q', 'que') |
|
1064
|
|
|
|
|
1065
|
|
|
r1_start = max(3, _sb_r1(word, _vowels)) |
|
1066
|
|
|
r2_start = _sb_r2(word, _vowels) |
|
1067
|
|
|
|
|
1068
|
|
|
# Step 1 |
|
1069
|
|
|
niss_flag = False |
|
1070
|
|
|
if word[-3:] == 'ern': |
|
1071
|
|
|
if len(word[r1_start:]) >= 3: |
|
1072
|
|
|
word = word[:-3] |
|
1073
|
|
|
elif word[-2:] == 'em': |
|
1074
|
|
|
if len(word[r1_start:]) >= 2: |
|
1075
|
|
|
word = word[:-2] |
|
1076
|
|
|
elif word[-2:] == 'er': |
|
1077
|
|
|
if len(word[r1_start:]) >= 2: |
|
1078
|
|
|
word = word[:-2] |
|
1079
|
|
|
elif word[-2:] == 'en': |
|
1080
|
|
|
if len(word[r1_start:]) >= 2: |
|
1081
|
|
|
word = word[:-2] |
|
1082
|
|
|
niss_flag = True |
|
1083
|
|
|
elif word[-2:] == 'es': |
|
1084
|
|
|
if len(word[r1_start:]) >= 2: |
|
1085
|
|
|
word = word[:-2] |
|
1086
|
|
|
niss_flag = True |
|
1087
|
|
|
elif word[-1:] == 'e': |
|
1088
|
|
|
if len(word[r1_start:]) >= 1: |
|
1089
|
|
|
word = word[:-1] |
|
1090
|
|
|
niss_flag = True |
|
1091
|
|
|
elif word[-1:] == 's': |
|
1092
|
|
|
if ((len(word[r1_start:]) >= 1 and len(word) >= 2 and |
|
1093
|
|
|
word[-2] in _s_endings)): |
|
1094
|
|
|
word = word[:-1] |
|
1095
|
|
|
|
|
1096
|
|
|
if niss_flag and word[-4:] == 'niss': |
|
1097
|
|
|
word = word[:-1] |
|
1098
|
|
|
|
|
1099
|
|
|
# Step 2 |
|
1100
|
|
|
if word[-3:] == 'est': |
|
1101
|
|
|
if len(word[r1_start:]) >= 3: |
|
1102
|
|
|
word = word[:-3] |
|
1103
|
|
|
elif word[-2:] == 'en': |
|
1104
|
|
|
if len(word[r1_start:]) >= 2: |
|
1105
|
|
|
word = word[:-2] |
|
1106
|
|
|
elif word[-2:] == 'er': |
|
1107
|
|
|
if len(word[r1_start:]) >= 2: |
|
1108
|
|
|
word = word[:-2] |
|
1109
|
|
|
elif word[-2:] == 'st': |
|
1110
|
|
|
if ((len(word[r1_start:]) >= 2 and len(word) >= 6 and |
|
1111
|
|
|
word[-3] in _st_endings)): |
|
1112
|
|
|
word = word[:-2] |
|
1113
|
|
|
|
|
1114
|
|
|
# Step 3 |
|
1115
|
|
|
if word[-4:] == 'isch': |
|
1116
|
|
|
if len(word[r2_start:]) >= 4 and word[-5] != 'e': |
|
1117
|
|
|
word = word[:-4] |
|
1118
|
|
|
elif word[-4:] in {'lich', 'heit'}: |
|
1119
|
|
|
if len(word[r2_start:]) >= 4: |
|
1120
|
|
|
word = word[:-4] |
|
1121
|
|
|
if ((word[-2:] in {'er', 'en'} and |
|
1122
|
|
|
len(word[r1_start:]) >= 2)): |
|
1123
|
|
|
word = word[:-2] |
|
1124
|
|
|
elif word[-4:] == 'keit': |
|
1125
|
|
|
if len(word[r2_start:]) >= 4: |
|
1126
|
|
|
word = word[:-4] |
|
1127
|
|
|
if word[-4:] == 'lich' and len(word[r2_start:]) >= 4: |
|
1128
|
|
|
word = word[:-4] |
|
1129
|
|
|
elif word[-2:] == 'ig' and len(word[r2_start:]) >= 2: |
|
1130
|
|
|
word = word[:-2] |
|
1131
|
|
|
elif word[-3:] in {'end', 'ung'}: |
|
1132
|
|
|
if len(word[r2_start:]) >= 3: |
|
1133
|
|
|
word = word[:-3] |
|
1134
|
|
|
if ((word[-2:] == 'ig' and len(word[r2_start:]) >= 2 and |
|
1135
|
|
|
word[-3] != 'e')): |
|
1136
|
|
|
word = word[:-2] |
|
1137
|
|
|
elif word[-2:] in {'ig', 'ik'}: |
|
1138
|
|
|
if len(word[r2_start:]) >= 2 and word[-3] != 'e': |
|
1139
|
|
|
word = word[:-2] |
|
1140
|
|
|
|
|
1141
|
|
|
# Change 'Y' and 'U' back to lowercase if survived stemming |
|
1142
|
|
|
for i in range(0, len(word)): |
|
1143
|
|
|
if word[i] == 'Y': |
|
1144
|
|
|
word = word[:i] + 'y' + word[i+1:] |
|
1145
|
|
|
elif word[i] == 'U': |
|
1146
|
|
|
word = word[:i] + 'u' + word[i+1:] |
|
1147
|
|
|
|
|
1148
|
|
|
# Remove umlauts |
|
1149
|
|
|
_umlauts = dict(zip((ord(_) for _ in 'äöü'), 'aou')) |
|
1150
|
|
|
word = word.translate(_umlauts) |
|
1151
|
|
|
|
|
1152
|
|
|
return word |
|
1153
|
|
|
|
|
1154
|
|
|
|
|
1155
|
|
|
def sb_dutch(word): |
|
1156
|
|
|
"""Return Snowball Dutch stem. |
|
1157
|
|
|
|
|
1158
|
|
|
The Snowball Dutch stemmer is defined at: |
|
1159
|
|
|
http://snowball.tartarus.org/algorithms/dutch/stemmer.html |
|
1160
|
|
|
|
|
1161
|
|
|
:param word: the word to calculate the stem of |
|
1162
|
|
|
:returns: word stem |
|
1163
|
|
|
:rtype: str |
|
1164
|
|
|
|
|
1165
|
|
|
>>> sb_dutch('lezen') |
|
1166
|
|
|
'lez' |
|
1167
|
|
|
>>> sb_dutch('opschorting') |
|
1168
|
|
|
'opschort' |
|
1169
|
|
|
>>> sb_dutch('ongrijpbaarheid') |
|
1170
|
|
|
'ongrijp' |
|
1171
|
|
|
""" |
|
1172
|
|
|
# pylint: disable=too-many-branches |
|
1173
|
|
|
|
|
1174
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y', 'è'} |
|
1175
|
|
|
_not_s_endings = {'a', 'e', 'i', 'j', 'o', 'u', 'y', 'è'} |
|
1176
|
|
|
|
|
1177
|
|
|
def _undouble(word): |
|
1178
|
|
|
"""Undouble endings -kk, -dd, and -tt.""" |
|
1179
|
|
|
if ((len(word) > 1 and word[-1] == word[-2] and |
|
1180
|
|
|
word[-1] in {'d', 'k', 't'})): |
|
1181
|
|
|
return word[:-1] |
|
1182
|
|
|
return word |
|
1183
|
|
|
|
|
1184
|
|
|
# lowercase, normalize, decompose, filter umlauts & acutes out, and compose |
|
1185
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1186
|
|
|
_accented = dict(zip((ord(_) for _ in 'äëïöüáéíóú'), 'aeiouaeiou')) |
|
1187
|
|
|
word = word.translate(_accented) |
|
1188
|
|
|
|
|
1189
|
|
|
for i in range(len(word)): |
|
1190
|
|
|
if i == 0 and word[0] == 'y': |
|
1191
|
|
|
word = 'Y' + word[1:] |
|
1192
|
|
|
elif word[i] == 'y' and word[i-1] in _vowels: |
|
1193
|
|
|
word = word[:i] + 'Y' + word[i+1:] |
|
1194
|
|
|
elif (word[i] == 'i' and word[i-1] in _vowels and i+1 < len(word) and |
|
1195
|
|
|
word[i+1] in _vowels): |
|
1196
|
|
|
word = word[:i] + 'I' + word[i+1:] |
|
1197
|
|
|
|
|
1198
|
|
|
r1_start = max(3, _sb_r1(word, _vowels)) |
|
1199
|
|
|
r2_start = _sb_r2(word, _vowels) |
|
1200
|
|
|
|
|
1201
|
|
|
# Step 1 |
|
1202
|
|
|
if word[-5:] == 'heden': |
|
1203
|
|
|
if len(word[r1_start:]) >= 5: |
|
1204
|
|
|
word = word[:-3] + 'id' |
|
1205
|
|
|
elif word[-3:] == 'ene': |
|
1206
|
|
|
if ((len(word[r1_start:]) >= 3 and |
|
1207
|
|
|
(word[-4] not in _vowels and word[-6:-3] != 'gem'))): |
|
1208
|
|
|
word = _undouble(word[:-3]) |
|
1209
|
|
|
elif word[-2:] == 'en': |
|
1210
|
|
|
if ((len(word[r1_start:]) >= 2 and |
|
1211
|
|
|
(word[-3] not in _vowels and word[-5:-2] != 'gem'))): |
|
1212
|
|
|
word = _undouble(word[:-2]) |
|
1213
|
|
|
elif word[-2:] == 'se': |
|
1214
|
|
|
if len(word[r1_start:]) >= 2 and word[-3] not in _not_s_endings: |
|
1215
|
|
|
word = word[:-2] |
|
1216
|
|
|
elif word[-1:] == 's': |
|
1217
|
|
|
if len(word[r1_start:]) >= 1 and word[-2] not in _not_s_endings: |
|
1218
|
|
|
word = word[:-1] |
|
1219
|
|
|
|
|
1220
|
|
|
# Step 2 |
|
1221
|
|
|
e_removed = False |
|
1222
|
|
|
if word[-1:] == 'e': |
|
1223
|
|
|
if len(word[r1_start:]) >= 1 and word[-2] not in _vowels: |
|
1224
|
|
|
word = _undouble(word[:-1]) |
|
1225
|
|
|
e_removed = True |
|
1226
|
|
|
|
|
1227
|
|
|
# Step 3a |
|
1228
|
|
|
if word[-4:] == 'heid': |
|
1229
|
|
|
if len(word[r2_start:]) >= 4 and word[-5] != 'c': |
|
1230
|
|
|
word = word[:-4] |
|
1231
|
|
|
if word[-2:] == 'en': |
|
1232
|
|
|
if ((len(word[r1_start:]) >= 2 and |
|
1233
|
|
|
(word[-3] not in _vowels and word[-5:-2] != 'gem'))): |
|
1234
|
|
|
word = _undouble(word[:-2]) |
|
1235
|
|
|
|
|
1236
|
|
|
# Step 3b |
|
1237
|
|
|
if word[-4:] == 'lijk': |
|
1238
|
|
|
if len(word[r2_start:]) >= 4: |
|
1239
|
|
|
word = word[:-4] |
|
1240
|
|
|
# Repeat step 2 |
|
1241
|
|
|
if word[-1:] == 'e': |
|
1242
|
|
|
if len(word[r1_start:]) >= 1 and word[-2] not in _vowels: |
|
1243
|
|
|
word = _undouble(word[:-1]) |
|
1244
|
|
|
elif word[-4:] == 'baar': |
|
1245
|
|
|
if len(word[r2_start:]) >= 4: |
|
1246
|
|
|
word = word[:-4] |
|
1247
|
|
|
elif word[-3:] in ('end', 'ing'): |
|
1248
|
|
|
if len(word[r2_start:]) >= 3: |
|
1249
|
|
|
word = word[:-3] |
|
1250
|
|
|
if ((word[-2:] == 'ig' and len(word[r2_start:]) >= 2 and |
|
1251
|
|
|
word[-3] != 'e')): |
|
1252
|
|
|
word = word[:-2] |
|
1253
|
|
|
else: |
|
1254
|
|
|
word = _undouble(word) |
|
1255
|
|
|
elif word[-3:] == 'bar': |
|
1256
|
|
|
if len(word[r2_start:]) >= 3 and e_removed: |
|
1257
|
|
|
word = word[:-3] |
|
1258
|
|
|
elif word[-2:] == 'ig': |
|
1259
|
|
|
if len(word[r2_start:]) >= 2 and word[-3] != 'e': |
|
1260
|
|
|
word = word[:-2] |
|
1261
|
|
|
|
|
1262
|
|
|
# Step 4 |
|
1263
|
|
|
if ((len(word) >= 4 and |
|
1264
|
|
|
word[-3] == word[-2] and word[-2] in {'a', 'e', 'o', 'u'} and |
|
1265
|
|
|
word[-4] not in _vowels and |
|
1266
|
|
|
word[-1] not in _vowels and word[-1] != 'I')): |
|
1267
|
|
|
word = word[:-2] + word[-1] |
|
1268
|
|
|
|
|
1269
|
|
|
# Change 'Y' and 'U' back to lowercase if survived stemming |
|
1270
|
|
|
for i in range(0, len(word)): |
|
1271
|
|
|
if word[i] == 'Y': |
|
1272
|
|
|
word = word[:i] + 'y' + word[i+1:] |
|
1273
|
|
|
elif word[i] == 'I': |
|
1274
|
|
|
word = word[:i] + 'i' + word[i+1:] |
|
1275
|
|
|
|
|
1276
|
|
|
return word |
|
1277
|
|
|
|
|
1278
|
|
|
|
|
1279
|
|
|
def sb_norwegian(word): |
|
1280
|
|
|
"""Return Snowball Norwegian stem. |
|
1281
|
|
|
|
|
1282
|
|
|
The Snowball Norwegian stemmer is defined at: |
|
1283
|
|
|
http://snowball.tartarus.org/algorithms/norwegian/stemmer.html |
|
1284
|
|
|
|
|
1285
|
|
|
:param word: the word to calculate the stem of |
|
1286
|
|
|
:returns: word stem |
|
1287
|
|
|
:rtype: str |
|
1288
|
|
|
|
|
1289
|
|
|
>>> sb_norwegian('lese') |
|
1290
|
|
|
'les' |
|
1291
|
|
|
>>> sb_norwegian('suspensjon') |
|
1292
|
|
|
'suspensjon' |
|
1293
|
|
|
>>> sb_norwegian('sikkerhet') |
|
1294
|
|
|
'sikker' |
|
1295
|
|
|
""" |
|
1296
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y', 'å', 'æ', 'ø'} |
|
1297
|
|
|
_s_endings = {'b', 'c', 'd', 'f', 'g', 'h', 'j', 'l', 'm', 'n', 'o', 'p', |
|
1298
|
|
|
'r', 't', 'v', 'y', 'z'} |
|
1299
|
|
|
# lowercase, normalize, and compose |
|
1300
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1301
|
|
|
|
|
1302
|
|
|
r1_start = min(max(3, _sb_r1(word, _vowels)), len(word)) |
|
1303
|
|
|
|
|
1304
|
|
|
# Step 1 |
|
1305
|
|
|
_r1 = word[r1_start:] |
|
1306
|
|
|
if _r1[-7:] == 'hetenes': |
|
1307
|
|
|
word = word[:-7] |
|
1308
|
|
|
elif _r1[-6:] in {'hetene', 'hetens'}: |
|
1309
|
|
|
word = word[:-6] |
|
1310
|
|
|
elif _r1[-5:] in {'heten', 'heter', 'endes'}: |
|
1311
|
|
|
word = word[:-5] |
|
1312
|
|
|
elif _r1[-4:] in {'ande', 'ende', 'edes', 'enes', 'erte'}: |
|
1313
|
|
|
if word[-4:] == 'erte': |
|
1314
|
|
|
word = word[:-2] |
|
1315
|
|
|
else: |
|
1316
|
|
|
word = word[:-4] |
|
1317
|
|
|
elif _r1[-3:] in {'ede', 'ane', 'ene', 'ens', 'ers', 'ets', 'het', 'ast', |
|
1318
|
|
|
'ert'}: |
|
1319
|
|
|
if word[-3:] == 'ert': |
|
1320
|
|
|
word = word[:-1] |
|
1321
|
|
|
else: |
|
1322
|
|
|
word = word[:-3] |
|
1323
|
|
|
elif _r1[-2:] in {'en', 'ar', 'er', 'as', 'es', 'et'}: |
|
1324
|
|
|
word = word[:-2] |
|
1325
|
|
|
elif _r1[-1:] in {'a', 'e'}: |
|
1326
|
|
|
word = word[:-1] |
|
1327
|
|
|
elif _r1[-1:] == 's': |
|
1328
|
|
|
if (((len(word) > 1 and word[-2] in _s_endings) or |
|
1329
|
|
|
(len(word) > 2 and word[-2] == 'k' and word[-3] not in _vowels))): |
|
1330
|
|
|
word = word[:-1] |
|
1331
|
|
|
|
|
1332
|
|
|
# Step 2 |
|
1333
|
|
|
if word[r1_start:][-2:] in {'dt', 'vt'}: |
|
1334
|
|
|
word = word[:-1] |
|
1335
|
|
|
|
|
1336
|
|
|
# Step 3 |
|
1337
|
|
|
_r1 = word[r1_start:] |
|
1338
|
|
|
if _r1[-7:] == 'hetslov': |
|
1339
|
|
|
word = word[:-7] |
|
1340
|
|
|
elif _r1[-4:] in {'eleg', 'elig', 'elov', 'slov'}: |
|
1341
|
|
|
word = word[:-4] |
|
1342
|
|
|
elif _r1[-3:] in {'leg', 'eig', 'lig', 'els', 'lov'}: |
|
1343
|
|
|
word = word[:-3] |
|
1344
|
|
|
elif _r1[-2:] == 'ig': |
|
1345
|
|
|
word = word[:-2] |
|
1346
|
|
|
|
|
1347
|
|
|
return word |
|
1348
|
|
|
|
|
1349
|
|
|
|
|
1350
|
|
|
def sb_swedish(word): |
|
1351
|
|
|
"""Return Snowball Swedish stem. |
|
1352
|
|
|
|
|
1353
|
|
|
The Snowball Swedish stemmer is defined at: |
|
1354
|
|
|
http://snowball.tartarus.org/algorithms/swedish/stemmer.html |
|
1355
|
|
|
|
|
1356
|
|
|
:param word: the word to calculate the stem of |
|
1357
|
|
|
:returns: word stem |
|
1358
|
|
|
:rtype: str |
|
1359
|
|
|
|
|
1360
|
|
|
>>> sb_swedish('undervisa') |
|
1361
|
|
|
'undervis' |
|
1362
|
|
|
>>> sb_swedish('suspension') |
|
1363
|
|
|
'suspension' |
|
1364
|
|
|
>>> sb_swedish('visshet') |
|
1365
|
|
|
'viss' |
|
1366
|
|
|
""" |
|
1367
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y', 'ä', 'å', 'ö'} |
|
1368
|
|
|
_s_endings = {'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', |
|
1369
|
|
|
'o', 'p', 'r', 't', 'v', 'y'} |
|
1370
|
|
|
|
|
1371
|
|
|
# lowercase, normalize, and compose |
|
1372
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1373
|
|
|
|
|
1374
|
|
|
r1_start = min(max(3, _sb_r1(word, _vowels)), len(word)) |
|
1375
|
|
|
|
|
1376
|
|
|
# Step 1 |
|
1377
|
|
|
_r1 = word[r1_start:] |
|
1378
|
|
|
if _r1[-7:] == 'heterna': |
|
1379
|
|
|
word = word[:-7] |
|
1380
|
|
|
elif _r1[-6:] == 'hetens': |
|
1381
|
|
|
word = word[:-6] |
|
1382
|
|
|
elif _r1[-5:] in {'anden', 'heten', 'heter', 'arnas', 'ernas', 'ornas', |
|
1383
|
|
|
'andes', 'arens', 'andet'}: |
|
1384
|
|
|
word = word[:-5] |
|
1385
|
|
|
elif _r1[-4:] in {'arna', 'erna', 'orna', 'ande', 'arne', 'aste', 'aren', |
|
1386
|
|
|
'ades', 'erns']): |
|
1387
|
|
|
word = word[:-4] |
|
1388
|
|
|
elif _r1[-3:] in {'ade', 'are', 'ern', 'ens', 'het', 'ast'}: |
|
1389
|
|
|
word = word[:-3] |
|
1390
|
|
|
elif _r1[-2:] in {'ad', 'en', 'ar', 'er', 'or', 'as', 'es', 'at'}: |
|
1391
|
|
|
word = word[:-2] |
|
1392
|
|
|
elif _r1[-1:] in {'a', 'e'}: |
|
1393
|
|
|
word = word[:-1] |
|
1394
|
|
|
elif _r1[-1:] == 's': |
|
1395
|
|
|
if len(word) > 1 and word[-2] in _s_endings: |
|
1396
|
|
|
word = word[:-1] |
|
1397
|
|
|
|
|
1398
|
|
|
# Step 2 |
|
1399
|
|
|
if word[r1_start:][-2:] in {'dd', 'gd', 'nn', 'dt', 'gt', 'kt', 'tt'}: |
|
1400
|
|
|
word = word[:-1] |
|
1401
|
|
|
|
|
1402
|
|
|
# Step 3 |
|
1403
|
|
|
_r1 = word[r1_start:] |
|
1404
|
|
|
if _r1[-5:] == 'fullt': |
|
1405
|
|
|
word = word[:-1] |
|
1406
|
|
|
elif _r1[-4:] == 'löst': |
|
1407
|
|
|
word = word[:-1] |
|
1408
|
|
|
elif _r1[-3:] in {'lig', 'els'}: |
|
1409
|
|
|
word = word[:-3] |
|
1410
|
|
|
elif _r1[-2:] == 'ig': |
|
1411
|
|
|
word = word[:-2] |
|
1412
|
|
|
|
|
1413
|
|
|
return word |
|
1414
|
|
|
|
|
1415
|
|
|
|
|
1416
|
|
|
def sb_danish(word): |
|
1417
|
|
|
"""Return Snowball Danish stem. |
|
1418
|
|
|
|
|
1419
|
|
|
The Snowball Danish stemmer is defined at: |
|
1420
|
|
|
http://snowball.tartarus.org/algorithms/danish/stemmer.html |
|
1421
|
|
|
|
|
1422
|
|
|
:param word: the word to calculate the stem of |
|
1423
|
|
|
:returns: word stem |
|
1424
|
|
|
:rtype: str |
|
1425
|
|
|
|
|
1426
|
|
|
>>> sb_danish('underviser') |
|
1427
|
|
|
'undervis' |
|
1428
|
|
|
>>> sb_danish('suspension') |
|
1429
|
|
|
'suspension' |
|
1430
|
|
|
>>> sb_danish('sikkerhed') |
|
1431
|
|
|
'sikker' |
|
1432
|
|
|
""" |
|
1433
|
|
|
_vowels = {'a', 'e', 'i', 'o', 'u', 'y', 'å', 'æ', 'ø'} |
|
1434
|
|
|
_s_endings = {'a', 'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', |
|
1435
|
|
|
'o', 'p', 'r', 't', 'v', 'y', 'z', 'å'} |
|
1436
|
|
|
|
|
1437
|
|
|
# lowercase, normalize, and compose |
|
1438
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1439
|
|
|
|
|
1440
|
|
|
r1_start = min(max(3, _sb_r1(word, _vowels)), len(word)) |
|
1441
|
|
|
|
|
1442
|
|
|
# Step 1 |
|
1443
|
|
|
_r1 = word[r1_start:] |
|
1444
|
|
|
if _r1[-7:] == 'erendes': |
|
1445
|
|
|
word = word[:-7] |
|
1446
|
|
|
elif _r1[-6:] in {'erende', 'hedens'}: |
|
1447
|
|
|
word = word[:-6] |
|
1448
|
|
|
elif _r1[-5:] in {'ethed', 'erede', 'heden', 'heder', 'endes', 'ernes', |
|
1449
|
|
|
'erens', 'erets'}: |
|
1450
|
|
|
word = word[:-5] |
|
1451
|
|
|
elif _r1[-4:] in {'ered', 'ende', 'erne', 'eren', 'erer', 'heds', 'enes', |
|
1452
|
|
|
'eres', 'eret'}: |
|
1453
|
|
|
word = word[:-4] |
|
1454
|
|
|
elif _r1[-3:] in {'hed', 'ene', 'ere', 'ens', 'ers', 'ets'}: |
|
1455
|
|
|
word = word[:-3] |
|
1456
|
|
|
elif _r1[-2:] in {'en', 'er', 'es', 'et'}: |
|
1457
|
|
|
word = word[:-2] |
|
1458
|
|
|
elif _r1[-1:] == 'e': |
|
1459
|
|
|
word = word[:-1] |
|
1460
|
|
|
elif _r1[-1:] == 's': |
|
1461
|
|
|
if len(word) > 1 and word[-2] in _s_endings: |
|
1462
|
|
|
word = word[:-1] |
|
1463
|
|
|
|
|
1464
|
|
|
# Step 2 |
|
1465
|
|
|
if word[r1_start:][-2:] in {'gd', 'dt', 'gt', 'kt'}: |
|
1466
|
|
|
word = word[:-1] |
|
1467
|
|
|
|
|
1468
|
|
|
# Step 3 |
|
1469
|
|
|
if word[-4:] == 'igst': |
|
1470
|
|
|
word = word[:-2] |
|
1471
|
|
|
|
|
1472
|
|
|
_r1 = word[r1_start:] |
|
1473
|
|
|
repeat_step2 = False |
|
1474
|
|
|
if _r1[-4:] == 'elig': |
|
1475
|
|
|
word = word[:-4] |
|
1476
|
|
|
repeat_step2 = True |
|
1477
|
|
|
elif _r1[-4:] == 'løst': |
|
1478
|
|
|
word = word[:-1] |
|
1479
|
|
|
elif _r1[-3:] in {'lig', 'els'}: |
|
1480
|
|
|
word = word[:-3] |
|
1481
|
|
|
repeat_step2 = True |
|
1482
|
|
|
elif _r1[-2:] == 'ig': |
|
1483
|
|
|
word = word[:-2] |
|
1484
|
|
|
repeat_step2 = True |
|
1485
|
|
|
|
|
1486
|
|
|
if repeat_step2: |
|
1487
|
|
|
if word[r1_start:][-2:] in {'gd', 'dt', 'gt', 'kt'}: |
|
1488
|
|
|
word = word[:-1] |
|
1489
|
|
|
|
|
1490
|
|
|
# Step 4 |
|
1491
|
|
|
if ((len(word[r1_start:]) >= 1 and len(word) >= 2 and |
|
1492
|
|
|
word[-1] == word[-2] and word[-1] not in _vowels)): |
|
1493
|
|
|
word = word[:-1] |
|
1494
|
|
|
|
|
1495
|
|
|
return word |
|
1496
|
|
|
|
|
1497
|
|
|
|
|
1498
|
|
|
def clef_german(word): |
|
1499
|
|
|
"""Return CLEF German stem. |
|
1500
|
|
|
|
|
1501
|
|
|
The CLEF German stemmer is defined at: |
|
1502
|
|
|
http://members.unine.ch/jacques.savoy/clef/germanStemmer.txt |
|
1503
|
|
|
|
|
1504
|
|
|
:param word: the word to calculate the stem of |
|
1505
|
|
|
:returns: word stem |
|
1506
|
|
|
:rtype: str |
|
1507
|
|
|
|
|
1508
|
|
|
>>> clef_german('lesen') |
|
1509
|
|
|
'lese' |
|
1510
|
|
|
>>> clef_german('graues') |
|
1511
|
|
|
'grau' |
|
1512
|
|
|
>>> clef_german('buchstabieren') |
|
1513
|
|
|
'buchstabier' |
|
1514
|
|
|
""" |
|
1515
|
|
|
# lowercase, normalize, and compose |
|
1516
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1517
|
|
|
|
|
1518
|
|
|
# remove umlauts |
|
1519
|
|
|
_umlauts = dict(zip((ord(_) for _ in 'äöü'), 'aou')) |
|
1520
|
|
|
word = word.translate(_umlauts) |
|
1521
|
|
|
|
|
1522
|
|
|
# remove plurals |
|
1523
|
|
|
wlen = len(word)-1 |
|
1524
|
|
|
|
|
1525
|
|
|
if wlen > 3: |
|
1526
|
|
|
if wlen > 5: |
|
1527
|
|
|
if word[-3:] == 'nen': |
|
1528
|
|
|
return word[:-3] |
|
1529
|
|
|
if wlen > 4: |
|
1530
|
|
|
if word[-2:] in {'en', 'se', 'es', 'er'}: |
|
1531
|
|
|
return word[:-2] |
|
1532
|
|
|
if word[-1] in {'e', 'n', 'r', 's'}: |
|
1533
|
|
|
return word[:-1] |
|
1534
|
|
|
return word |
|
1535
|
|
|
|
|
1536
|
|
|
|
|
1537
|
|
|
def clef_german_plus(word): |
|
1538
|
|
|
"""Return 'CLEF German stemmer plus' stem. |
|
1539
|
|
|
|
|
1540
|
|
|
The CLEF German stemmer plus is defined at: |
|
1541
|
|
|
http://members.unine.ch/jacques.savoy/clef/germanStemmerPlus.txt |
|
1542
|
|
|
|
|
1543
|
|
|
:param word: the word to calculate the stem of |
|
1544
|
|
|
:returns: word stem |
|
1545
|
|
|
:rtype: str |
|
1546
|
|
|
|
|
1547
|
|
|
>>> clef_german_plus('lesen') |
|
1548
|
|
|
'les' |
|
1549
|
|
|
>>> clef_german_plus('graues') |
|
1550
|
|
|
'grau' |
|
1551
|
|
|
>>> clef_german_plus('buchstabieren') |
|
1552
|
|
|
'buchstabi' |
|
1553
|
|
|
""" |
|
1554
|
|
|
_st_ending = {'b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 't'} |
|
1555
|
|
|
|
|
1556
|
|
|
# lowercase, normalize, and compose |
|
1557
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1558
|
|
|
|
|
1559
|
|
|
# remove umlauts |
|
1560
|
|
|
_accents = dict(zip((ord(_) for _ in 'äàáâöòóôïìíîüùúû'), |
|
1561
|
|
|
'aaaaooooiiiiuuuu')) |
|
1562
|
|
|
word = word.translate(_accents) |
|
1563
|
|
|
|
|
1564
|
|
|
# Step 1 |
|
1565
|
|
|
wlen = len(word)-1 |
|
1566
|
|
|
if wlen > 4 and word[-3:] == 'ern': |
|
1567
|
|
|
word = word[:-3] |
|
1568
|
|
|
elif wlen > 3 and word[-2:] in {'em', 'en', 'er', 'es'}: |
|
1569
|
|
|
word = word[:-2] |
|
1570
|
|
|
elif wlen > 2 and (word[-1] == 'e' or |
|
1571
|
|
|
(word[-1] == 's' and word[-2] in _st_ending)): |
|
1572
|
|
|
word = word[:-1] |
|
1573
|
|
|
|
|
1574
|
|
|
# Step 2 |
|
1575
|
|
|
wlen = len(word)-1 |
|
1576
|
|
|
if wlen > 4 and word[-3:] == 'est': |
|
1577
|
|
|
word = word[:-3] |
|
1578
|
|
|
elif wlen > 3 and (word[-2:] in {'er', 'en'} or |
|
1579
|
|
|
(word[-2:] == 'st' and word[-3] in _st_ending)): |
|
1580
|
|
|
word = word[:-2] |
|
1581
|
|
|
|
|
1582
|
|
|
return word |
|
1583
|
|
|
|
|
1584
|
|
|
|
|
1585
|
|
|
def clef_swedish(word): |
|
1586
|
|
|
"""Return CLEF Swedish stem. |
|
1587
|
|
|
|
|
1588
|
|
|
The CLEF Swedish stemmer is defined at: |
|
1589
|
|
|
http://members.unine.ch/jacques.savoy/clef/swedishStemmer.txt |
|
1590
|
|
|
|
|
1591
|
|
|
:param word: the word to calculate the stem of |
|
1592
|
|
|
:returns: word stem |
|
1593
|
|
|
:rtype: str |
|
1594
|
|
|
|
|
1595
|
|
|
>>> clef_swedish('undervisa') |
|
1596
|
|
|
'undervis' |
|
1597
|
|
|
>>> clef_swedish('suspension') |
|
1598
|
|
|
'suspensio' |
|
1599
|
|
|
>>> clef_swedish('visshet') |
|
1600
|
|
|
'viss' |
|
1601
|
|
|
""" |
|
1602
|
|
|
wlen = len(word)-1 |
|
1603
|
|
|
|
|
1604
|
|
|
if wlen > 3 and word[-1] == 's': |
|
1605
|
|
|
word = word[:-1] |
|
1606
|
|
|
wlen -= 1 |
|
1607
|
|
|
|
|
1608
|
|
|
if wlen > 6: |
|
1609
|
|
|
if word[-5:] in {'elser', 'heten'}: |
|
1610
|
|
|
return word[:-5] |
|
1611
|
|
|
if wlen > 5: |
|
1612
|
|
|
if word[-4:] in {'arne', 'erna', 'ande', 'else', 'aste', 'orna', |
|
1613
|
|
|
'aren'}: |
|
1614
|
|
|
return word[:-4] |
|
1615
|
|
|
if wlen > 4: |
|
1616
|
|
|
if word[-3:] in {'are', 'ast', 'het'}: |
|
1617
|
|
|
return word[:-3] |
|
1618
|
|
|
if wlen > 3: |
|
1619
|
|
|
if word[-2:] in {'ar', 'er', 'or', 'en', 'at', 'te', 'et'}: |
|
1620
|
|
|
return word[:-2] |
|
1621
|
|
|
if wlen > 2: |
|
1622
|
|
|
if word[-1] in {'a', 'e', 'n', 't'}: |
|
1623
|
|
|
return word[:-1] |
|
1624
|
|
|
return word |
|
1625
|
|
|
|
|
1626
|
|
|
|
|
1627
|
|
|
def caumanns(word): |
|
1628
|
|
|
"""Return Caumanns German stem. |
|
1629
|
|
|
|
|
1630
|
|
|
Jörg Caumanns' stemmer is described in his article at: |
|
1631
|
|
|
http://edocs.fu-berlin.de/docs/servlets/MCRFileNodeServlet/FUDOCS_derivate_000000000350/tr-b-99-16.pdf |
|
1632
|
|
|
|
|
1633
|
|
|
This implementation is based on the GermanStemFilter described at: |
|
1634
|
|
|
http://www.evelix.ch/unternehmen/Blog/evelix/2013/11/11/inner-workings-of-the-german-analyzer-in-lucene |
|
1635
|
|
|
|
|
1636
|
|
|
:param word: the word to calculate the stem of |
|
1637
|
|
|
:returns: word stem |
|
1638
|
|
|
:rtype: str |
|
1639
|
|
|
|
|
1640
|
|
|
>>> caumanns('lesen') |
|
1641
|
|
|
'les' |
|
1642
|
|
|
>>> caumanns('graues') |
|
1643
|
|
|
'grau' |
|
1644
|
|
|
>>> caumanns('buchstabieren') |
|
1645
|
|
|
'buchstabier' |
|
1646
|
|
|
""" |
|
1647
|
|
|
if not word: |
|
1648
|
|
|
return '' |
|
1649
|
|
|
|
|
1650
|
|
|
upper_initial = word[0].isupper() |
|
1651
|
|
|
word = unicodedata.normalize('NFC', text_type(word.lower())) |
|
1652
|
|
|
|
|
1653
|
|
|
# # Part 2: Substitution |
|
1654
|
|
|
# 1. Change umlauts to corresponding vowels & ß to ss |
|
1655
|
|
|
_umlauts = dict(zip((ord(_) for _ in 'äöü'), 'aou')) |
|
1656
|
|
|
word = word.translate(_umlauts) |
|
1657
|
|
|
word = word.replace('ß', 'ss') |
|
1658
|
|
|
|
|
1659
|
|
|
# 2. Change second of doubled characters to * |
|
1660
|
|
|
newword = word[0] |
|
1661
|
|
|
for i in range(1, len(word)): |
|
1662
|
|
|
if newword[i-1] == word[i]: |
|
1663
|
|
|
newword += '*' |
|
1664
|
|
|
else: |
|
1665
|
|
|
newword += word[i] |
|
1666
|
|
|
word = newword |
|
1667
|
|
|
|
|
1668
|
|
|
# 3. Replace sch, ch, ei, ie with $, §, %, & |
|
1669
|
|
|
word = word.replace('sch', '$') |
|
1670
|
|
|
word = word.replace('ch', '§') |
|
1671
|
|
|
word = word.replace('ei', '%') |
|
1672
|
|
|
word = word.replace('ie', '&') |
|
1673
|
|
|
word = word.replace('ig', '#') |
|
1674
|
|
|
word = word.replace('st', '!') |
|
1675
|
|
|
|
|
1676
|
|
|
# # Part 1: Recursive Context-Free Stripping |
|
1677
|
|
|
# 1. Remove the following 7 suffixes recursively |
|
1678
|
|
|
while len(word) > 3: |
|
1679
|
|
|
if (((len(word) > 4 and word[-2:] in {'em', 'er'}) or |
|
1680
|
|
|
(len(word) > 5 and word[-2:] == 'nd'))): |
|
1681
|
|
|
word = word[:-2] |
|
1682
|
|
|
elif ((word[-1] in {'e', 's', 'n'}) or |
|
1683
|
|
|
(not upper_initial and word[-1] in {'t', '!'})): |
|
1684
|
|
|
word = word[:-1] |
|
1685
|
|
|
else: |
|
1686
|
|
|
break |
|
1687
|
|
|
|
|
1688
|
|
|
# Additional optimizations: |
|
1689
|
|
|
if len(word) > 5 and word[-5:] == 'erin*': |
|
1690
|
|
|
word = word[:-1] |
|
1691
|
|
|
if word[-1] == 'z': |
|
1692
|
|
|
word = word[:-1] + 'x' |
|
1693
|
|
|
|
|
1694
|
|
|
# Reverse substitutions: |
|
1695
|
|
|
word = word.replace('$', 'sch') |
|
1696
|
|
|
word = word.replace('§', 'ch') |
|
1697
|
|
|
word = word.replace('%', 'ei') |
|
1698
|
|
|
word = word.replace('&', 'ie') |
|
1699
|
|
|
word = word.replace('#', 'ig') |
|
1700
|
|
|
word = word.replace('!', 'st') |
|
1701
|
|
|
|
|
1702
|
|
|
# Expand doubled |
|
1703
|
|
|
word = ''.join([word[0]] + [word[i-1] if word[i] == '*' else word[i] for |
|
1704
|
|
|
i in range(1, len(word))]) |
|
1705
|
|
|
|
|
1706
|
|
|
# Finally, convert gege to ge |
|
1707
|
|
|
if len(word) > 4: |
|
1708
|
|
|
word = word.replace('gege', 'ge', 1) |
|
1709
|
|
|
|
|
1710
|
|
|
return word |
|
1711
|
|
|
|
|
1712
|
|
|
|
|
1713
|
|
|
# def uealite(word): |
|
1714
|
|
|
# """Return UEA-Lite stem. |
|
1715
|
|
|
# |
|
1716
|
|
|
# The UEA-Lite stemmer is defined in Marie-Claire Jenkins and Dan Smith's |
|
1717
|
|
|
# article at: |
|
1718
|
|
|
# http://wayback.archive.org/web/20121012154211/http://www.uea.ac.uk/polopoly_fs/1.85493!stemmer25feb.pdf |
|
1719
|
|
|
# |
|
1720
|
|
|
# :param word: the word to calculate the stem of |
|
1721
|
|
|
# :returns: word stem |
|
1722
|
|
|
# :rtype: str |
|
1723
|
|
|
# """ |
|
1724
|
|
|
# return word |
|
1725
|
|
|
|
|
1726
|
|
|
|
|
1727
|
|
|
def lancaster(word): |
|
1728
|
|
|
"""Return Lancaster stem. |
|
1729
|
|
|
|
|
1730
|
|
|
Implementation of the Lancaster Stemming Algorithm, developed by |
|
1731
|
|
|
Chris Paice, with the assistance of Gareth Husk |
|
1732
|
|
|
|
|
1733
|
|
|
Arguments: |
|
1734
|
|
|
word -- the word to calculate the stem of |
|
1735
|
|
|
|
|
1736
|
|
|
Description: |
|
1737
|
|
|
The Lancaster Stemming Algorithm, described at: |
|
1738
|
|
|
http://wayback.archive.org/web/20140826000545/http://www.comp.lancs.ac.uk/computing/research/stemming/Links/paice.htm |
|
1739
|
|
|
|
|
1740
|
|
|
Based on the Paice & Husk's original Pascal reference implementation: |
|
1741
|
|
|
http://wayback.archive.org/web/20150104225538/http://www.comp.lancs.ac.uk/computing/research/stemming/Files/Pascal.zip |
|
1742
|
|
|
""" |
|
1743
|
|
|
_lancaster_rules = ('ai*2.', 'a*1.', 'bb1.', 'city3s.', 'ci2>', 'cn1t>', |
|
1744
|
|
|
'dd1.', 'dei3y>', 'deec2ss.', 'dee1.', 'de2>', |
|
1745
|
|
|
'dooh4>', 'e1>', 'feil1v.', 'fi2>', 'gni3>', 'gai3y.', |
|
1746
|
|
|
'ga2>', 'gg1.', 'ht*2.', 'hsiug5ct.', 'hsi3>', 'i*1.', |
|
1747
|
|
|
'i1y>', 'ji1d.', 'juf1s.', 'ju1d.', 'jo1d.', 'jeh1r.', |
|
1748
|
|
|
'jrev1t.', 'jsim2t.', 'jn1d.', 'j1s.', 'lbaifi6.', |
|
1749
|
|
|
'lbai4y.', 'lba3>', 'lbi3.', 'lib2l>', 'lc1.', |
|
1750
|
|
|
'lufi4y.', 'luf3>', 'lu2.', 'lai3>', 'lau3>', 'la2>', |
|
1751
|
|
|
'll1.', 'mui3.', 'mu*2.', 'msi3>', 'mm1.', 'nois4j>', |
|
1752
|
|
|
'noix4ct.', 'noi3>', 'nai3>', 'na2>', 'nee0.', 'ne2>', |
|
1753
|
|
|
'nn1.', 'pihs4>', 'pp1.', 're2>', 'rae0.', 'ra2.', |
|
1754
|
|
|
'ro2>', 'ru2>', 'rr1.', 'rt1>', 'rei3y>', 'sei3y>', |
|
1755
|
|
|
'sis2.', 'si2>', 'ssen4>', 'ss0.', 'suo3>', 'su*2.', |
|
1756
|
|
|
's*1>', 's0.', 'tacilp4y.', 'ta2>', 'tnem4>', 'tne3>', |
|
1757
|
|
|
'tna3>', 'tpir2b.', 'tpro2b.', 'tcud1.', 'tpmus2.', |
|
1758
|
|
|
'tpec2iv.', 'tulo2v.', 'tsis0.', 'tsi3>', 'tt1.', |
|
1759
|
|
|
'uqi3.', 'ugo1.', 'vis3j>', 'vie0.', 'vi2>', 'ylb1>', |
|
1760
|
|
|
'yli3y>', 'ylp0.', 'yl2>', 'ygo1.', 'yhp1.', 'ymo1.', |
|
1761
|
|
|
'ypo1.', 'yti3>', 'yte3>', 'ytl2.', 'yrtsi5.', |
|
1762
|
|
|
'yra3>', 'yro3>', 'yfi3.', 'ycn2t>', 'yca3>', 'zi2>', |
|
1763
|
|
|
'zy1s.') |
|
1764
|
|
|
|
|
1765
|
|
|
_rule_table = [] |
|
1766
|
|
|
_rule_index = {'a': -1, 'b': -1, 'c': -1, 'd': -1, 'e': -1, 'f': -1, |
|
1767
|
|
|
'g': -1, 'h': -1, 'i': -1, 'j': -1, 'k': -1, 'l': -1, |
|
1768
|
|
|
'm': -1, 'n': -1, 'o': -1, 'p': -1, 'q': -1, 'r': -1, |
|
1769
|
|
|
's': -1, 't': -1, 'u': -1, 'v': -1, 'w': -1, 'x': -1, |
|
1770
|
|
|
'y': -1, 'z': -1} |
|
1771
|
|
|
|
|
1772
|
|
|
def read_rules(stem_rules=_lancaster_rules): |
|
1773
|
|
|
"""Read the rules table. |
|
1774
|
|
|
|
|
1775
|
|
|
read_rules reads in stemming rules from a text file and enter them |
|
1776
|
|
|
into _rule_table. _rule_index is set up to provide faster access to |
|
1777
|
|
|
relevant rules. |
|
1778
|
|
|
""" |
|
1779
|
|
|
for rule in stem_rules: |
|
1780
|
|
|
_rule_table.append(rule) |
|
1781
|
|
|
if _rule_index[rule[0]] == -1: |
|
1782
|
|
|
_rule_index[rule[0]] = len(_rule_table)-1 |
|
1783
|
|
|
|
|
1784
|
|
|
def stemmers(word): |
|
1785
|
|
|
"""Reduce a word. |
|
1786
|
|
|
|
|
1787
|
|
|
stemmers takes the specified word and reduces it to a set by |
|
1788
|
|
|
referring to _rule_table |
|
1789
|
|
|
""" |
|
1790
|
|
|
# TODO: This looks very incomplete. |
|
1791
|
|
|
return word |
|
1792
|
|
|
|
chrislit /
abydos
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