Source code for nltk.stem.snowball

# -*- coding: utf-8 -*-
#
# Natural Language Toolkit: Snowball Stemmer
#
# Copyright (C) 2001-2017 NLTK Project
# Author: Peter Michael Stahl <pemistahl@gmail.com>
#         Peter Ljunglof <peter.ljunglof@heatherleaf.se> (revisions)
# Algorithms: Dr Martin Porter <martin@tartarus.org>
# URL: <http://nltk.org/>
# For license information, see LICENSE.TXT

"""
Snowball stemmers

This module provides a port of the Snowball stemmers
developed by Martin Porter.

There is also a demo function: `snowball.demo()`.

"""
from __future__ import unicode_literals, print_function

from nltk import compat
from nltk.corpus import stopwords
from nltk.stem import porter
from nltk.stem.util import suffix_replace

from nltk.stem.api import StemmerI


[docs]class SnowballStemmer(StemmerI): """ Snowball Stemmer The following languages are supported: Danish, Dutch, English, Finnish, French, German, Hungarian, Italian, Norwegian, Portuguese, Romanian, Russian, Spanish and Swedish. The algorithm for English is documented here: Porter, M. \"An algorithm for suffix stripping.\" Program 14.3 (1980): 130-137. The algorithms have been developed by Martin Porter. These stemmers are called Snowball, because Porter created a programming language with this name for creating new stemming algorithms. There is more information available at http://snowball.tartarus.org/ The stemmer is invoked as shown below: >>> from nltk.stem import SnowballStemmer >>> print(" ".join(SnowballStemmer.languages)) # See which languages are supported danish dutch english finnish french german hungarian italian norwegian porter portuguese romanian russian spanish swedish >>> stemmer = SnowballStemmer("german") # Choose a language >>> stemmer.stem("Autobahnen") # Stem a word 'autobahn' Invoking the stemmers that way is useful if you do not know the language to be stemmed at runtime. Alternatively, if you already know the language, then you can invoke the language specific stemmer directly: >>> from nltk.stem.snowball import GermanStemmer >>> stemmer = GermanStemmer() >>> stemmer.stem("Autobahnen") 'autobahn' :param language: The language whose subclass is instantiated. :type language: str or unicode :param ignore_stopwords: If set to True, stopwords are not stemmed and returned unchanged. Set to False by default. :type ignore_stopwords: bool :raise ValueError: If there is no stemmer for the specified language, a ValueError is raised. """ languages = ("danish", "dutch", "english", "finnish", "french", "german", "hungarian", "italian", "norwegian", "porter", "portuguese", "romanian", "russian", "spanish", "swedish") def __init__(self, language, ignore_stopwords=False): if language not in self.languages: raise ValueError("The language '{0}' is not supported.".format(language)) stemmerclass = globals()[language.capitalize() + "Stemmer"] self.stemmer = stemmerclass(ignore_stopwords) self.stem = self.stemmer.stem self.stopwords = self.stemmer.stopwords
@compat.python_2_unicode_compatible class _LanguageSpecificStemmer(StemmerI): """ This helper subclass offers the possibility to invoke a specific stemmer directly. This is useful if you already know the language to be stemmed at runtime. Create an instance of the Snowball stemmer. :param ignore_stopwords: If set to True, stopwords are not stemmed and returned unchanged. Set to False by default. :type ignore_stopwords: bool """ def __init__(self, ignore_stopwords=False): # The language is the name of the class, minus the final "Stemmer". language = type(self).__name__.lower() if language.endswith("stemmer"): language = language[:-7] self.stopwords = set() if ignore_stopwords: try: for word in stopwords.words(language): self.stopwords.add(word) except IOError: raise ValueError("{!r} has no list of stopwords. Please set" " 'ignore_stopwords' to 'False'.".format(self)) def __repr__(self): """ Print out the string representation of the respective class. """ return "<{0}>".format(type(self).__name__)
[docs]class PorterStemmer(_LanguageSpecificStemmer, porter.PorterStemmer): """ A word stemmer based on the original Porter stemming algorithm. Porter, M. \"An algorithm for suffix stripping.\" Program 14.3 (1980): 130-137. A few minor modifications have been made to Porter's basic algorithm. See the source code of the module nltk.stem.porter for more information. """ def __init__(self, ignore_stopwords=False): _LanguageSpecificStemmer.__init__(self, ignore_stopwords) porter.PorterStemmer.__init__(self)
class _ScandinavianStemmer(_LanguageSpecificStemmer): """ This subclass encapsulates a method for defining the string region R1. It is used by the Danish, Norwegian, and Swedish stemmer. """ def _r1_scandinavian(self, word, vowels): """ Return the region R1 that is used by the Scandinavian stemmers. R1 is the region after the first non-vowel following a vowel, or is the null region at the end of the word if there is no such non-vowel. But then R1 is adjusted so that the region before it contains at least three letters. :param word: The word whose region R1 is determined. :type word: str or unicode :param vowels: The vowels of the respective language that are used to determine the region R1. :type vowels: unicode :return: the region R1 for the respective word. :rtype: unicode :note: This helper method is invoked by the respective stem method of the subclasses DanishStemmer, NorwegianStemmer, and SwedishStemmer. It is not to be invoked directly! """ r1 = "" for i in range(1, len(word)): if word[i] not in vowels and word[i-1] in vowels: if len(word[:i+1]) < 3 and len(word[:i+1]) > 0: r1 = word[3:] elif len(word[:i+1]) >= 3: r1 = word[i+1:] else: return word break return r1 class _StandardStemmer(_LanguageSpecificStemmer): """ This subclass encapsulates two methods for defining the standard versions of the string regions R1, R2, and RV. """ def _r1r2_standard(self, word, vowels): """ Return the standard interpretations of the string regions R1 and R2. R1 is the region after the first non-vowel following a vowel, or is the null region at the end of the word if there is no such non-vowel. R2 is the region after the first non-vowel following a vowel in R1, or is the null region at the end of the word if there is no such non-vowel. :param word: The word whose regions R1 and R2 are determined. :type word: str or unicode :param vowels: The vowels of the respective language that are used to determine the regions R1 and R2. :type vowels: unicode :return: (r1,r2), the regions R1 and R2 for the respective word. :rtype: tuple :note: This helper method is invoked by the respective stem method of the subclasses DutchStemmer, FinnishStemmer, FrenchStemmer, GermanStemmer, ItalianStemmer, PortugueseStemmer, RomanianStemmer, and SpanishStemmer. It is not to be invoked directly! :note: A detailed description of how to define R1 and R2 can be found at http://snowball.tartarus.org/texts/r1r2.html """ r1 = "" r2 = "" for i in range(1, len(word)): if word[i] not in vowels and word[i-1] in vowels: r1 = word[i+1:] break for i in range(1, len(r1)): if r1[i] not in vowels and r1[i-1] in vowels: r2 = r1[i+1:] break return (r1, r2) def _rv_standard(self, word, vowels): """ Return the standard interpretation of the string region RV. If the second letter is a consonant, RV is the region after the next following vowel. If the first two letters are vowels, RV is the region after the next following consonant. Otherwise, RV is the region after the third letter. :param word: The word whose region RV is determined. :type word: str or unicode :param vowels: The vowels of the respective language that are used to determine the region RV. :type vowels: unicode :return: the region RV for the respective word. :rtype: unicode :note: This helper method is invoked by the respective stem method of the subclasses ItalianStemmer, PortugueseStemmer, RomanianStemmer, and SpanishStemmer. It is not to be invoked directly! """ rv = "" if len(word) >= 2: if word[1] not in vowels: for i in range(2, len(word)): if word[i] in vowels: rv = word[i+1:] break elif word[0] in vowels and word[1] in vowels: for i in range(2, len(word)): if word[i] not in vowels: rv = word[i+1:] break else: rv = word[3:] return rv
[docs]class DanishStemmer(_ScandinavianStemmer): """ The Danish Snowball stemmer. :cvar __vowels: The Danish vowels. :type __vowels: unicode :cvar __consonants: The Danish consonants. :type __consonants: unicode :cvar __double_consonants: The Danish double consonants. :type __double_consonants: tuple :cvar __s_ending: Letters that may directly appear before a word final 's'. :type __s_ending: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :note: A detailed description of the Danish stemming algorithm can be found under http://snowball.tartarus.org/algorithms/danish/stemmer.html """ # The language's vowels and other important characters are defined. __vowels = "aeiouy\xE6\xE5\xF8" __consonants = "bcdfghjklmnpqrstvwxz" __double_consonants = ("bb", "cc", "dd", "ff", "gg", "hh", "jj", "kk", "ll", "mm", "nn", "pp", "qq", "rr", "ss", "tt", "vv", "ww", "xx", "zz") __s_ending = "abcdfghjklmnoprtvyz\xE5" # The different suffixes, divided into the algorithm's steps # and organized by length, are listed in tuples. __step1_suffixes = ("erendes", "erende", "hedens", "ethed", "erede", "heden", "heder", "endes", "ernes", "erens", "erets", "ered", "ende", "erne", "eren", "erer", "heds", "enes", "eres", "eret", "hed", "ene", "ere", "ens", "ers", "ets", "en", "er", "es", "et", "e", "s") __step2_suffixes = ("gd", "dt", "gt", "kt") __step3_suffixes = ("elig", "l\xF8st", "lig", "els", "ig")
[docs] def stem(self, word): """ Stem a Danish word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ # Every word is put into lower case for normalization. word = word.lower() if word in self.stopwords: return word # After this, the required regions are generated # by the respective helper method. r1 = self._r1_scandinavian(word, self.__vowels) # Then the actual stemming process starts. # Every new step is explicitly indicated # according to the descriptions on the Snowball website. # STEP 1 for suffix in self.__step1_suffixes: if r1.endswith(suffix): if suffix == "s": if word[-2] in self.__s_ending: word = word[:-1] r1 = r1[:-1] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 2 for suffix in self.__step2_suffixes: if r1.endswith(suffix): word = word[:-1] r1 = r1[:-1] break # STEP 3 if r1.endswith("igst"): word = word[:-2] r1 = r1[:-2] for suffix in self.__step3_suffixes: if r1.endswith(suffix): if suffix == "l\xF8st": word = word[:-1] r1 = r1[:-1] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] if r1.endswith(self.__step2_suffixes): word = word[:-1] r1 = r1[:-1] break # STEP 4: Undouble for double_cons in self.__double_consonants: if word.endswith(double_cons) and len(word) > 3: word = word[:-1] break return word
[docs]class DutchStemmer(_StandardStemmer): """ The Dutch Snowball stemmer. :cvar __vowels: The Dutch vowels. :type __vowels: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step3b_suffixes: Suffixes to be deleted in step 3b of the algorithm. :type __step3b_suffixes: tuple :note: A detailed description of the Dutch stemming algorithm can be found under http://snowball.tartarus.org/algorithms/dutch/stemmer.html """ __vowels = "aeiouy\xE8" __step1_suffixes = ("heden", "ene", "en", "se", "s") __step3b_suffixes = ("baar", "lijk", "bar", "end", "ing", "ig")
[docs] def stem(self, word): """ Stem a Dutch word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step2_success = False # Vowel accents are removed. word = (word.replace("\xE4", "a").replace("\xE1", "a") .replace("\xEB", "e").replace("\xE9", "e") .replace("\xED", "i").replace("\xEF", "i") .replace("\xF6", "o").replace("\xF3", "o") .replace("\xFC", "u").replace("\xFA", "u")) # An initial 'y', a 'y' after a vowel, # and an 'i' between self.__vowels is put into upper case. # As from now these are treated as consonants. if word.startswith("y"): word = "".join(("Y", word[1:])) for i in range(1, len(word)): if word[i-1] in self.__vowels and word[i] == "y": word = "".join((word[:i], "Y", word[i+1:])) for i in range(1, len(word)-1): if (word[i-1] in self.__vowels and word[i] == "i" and word[i+1] in self.__vowels): word = "".join((word[:i], "I", word[i+1:])) r1, r2 = self._r1r2_standard(word, self.__vowels) # R1 is adjusted so that the region before it # contains at least 3 letters. for i in range(1, len(word)): if word[i] not in self.__vowels and word[i-1] in self.__vowels: if len(word[:i+1]) < 3 and len(word[:i+1]) > 0: r1 = word[3:] elif len(word[:i+1]) == 0: return word break # STEP 1 for suffix in self.__step1_suffixes: if r1.endswith(suffix): if suffix == "heden": word = suffix_replace(word, suffix, "heid") r1 = suffix_replace(r1, suffix, "heid") if r2.endswith("heden"): r2 = suffix_replace(r2, suffix, "heid") elif (suffix in ("ene", "en") and not word.endswith("heden") and word[-len(suffix)-1] not in self.__vowels and word[-len(suffix)-3:-len(suffix)] != "gem"): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] if word.endswith(("kk", "dd", "tt")): word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] elif (suffix in ("se", "s") and word[-len(suffix)-1] not in self.__vowels and word[-len(suffix)-1] != "j"): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 2 if r1.endswith("e") and word[-2] not in self.__vowels: step2_success = True word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] if word.endswith(("kk", "dd", "tt")): word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] # STEP 3a if r2.endswith("heid") and word[-5] != "c": word = word[:-4] r1 = r1[:-4] r2 = r2[:-4] if (r1.endswith("en") and word[-3] not in self.__vowels and word[-5:-2] != "gem"): word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] if word.endswith(("kk", "dd", "tt")): word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] # STEP 3b: Derivational suffixes for suffix in self.__step3b_suffixes: if r2.endswith(suffix): if suffix in ("end", "ing"): word = word[:-3] r2 = r2[:-3] if r2.endswith("ig") and word[-3] != "e": word = word[:-2] else: if word.endswith(("kk", "dd", "tt")): word = word[:-1] elif suffix == "ig" and word[-3] != "e": word = word[:-2] elif suffix == "lijk": word = word[:-4] r1 = r1[:-4] if r1.endswith("e") and word[-2] not in self.__vowels: word = word[:-1] if word.endswith(("kk", "dd", "tt")): word = word[:-1] elif suffix == "baar": word = word[:-4] elif suffix == "bar" and step2_success: word = word[:-3] break # STEP 4: Undouble vowel if len(word) >= 4: if word[-1] not in self.__vowels and word[-1] != "I": if word[-3:-1] in ("aa", "ee", "oo", "uu"): if word[-4] not in self.__vowels: word = "".join((word[:-3], word[-3], word[-1])) # All occurrences of 'I' and 'Y' are put back into lower case. word = word.replace("I", "i").replace("Y", "y") return word
[docs]class EnglishStemmer(_StandardStemmer): """ The English Snowball stemmer. :cvar __vowels: The English vowels. :type __vowels: unicode :cvar __double_consonants: The English double consonants. :type __double_consonants: tuple :cvar __li_ending: Letters that may directly appear before a word final 'li'. :type __li_ending: unicode :cvar __step0_suffixes: Suffixes to be deleted in step 0 of the algorithm. :type __step0_suffixes: tuple :cvar __step1a_suffixes: Suffixes to be deleted in step 1a of the algorithm. :type __step1a_suffixes: tuple :cvar __step1b_suffixes: Suffixes to be deleted in step 1b of the algorithm. :type __step1b_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :cvar __step4_suffixes: Suffixes to be deleted in step 4 of the algorithm. :type __step4_suffixes: tuple :cvar __step5_suffixes: Suffixes to be deleted in step 5 of the algorithm. :type __step5_suffixes: tuple :cvar __special_words: A dictionary containing words which have to be stemmed specially. :type __special_words: dict :note: A detailed description of the English stemming algorithm can be found under http://snowball.tartarus.org/algorithms/english/stemmer.html """ __vowels = "aeiouy" __double_consonants = ("bb", "dd", "ff", "gg", "mm", "nn", "pp", "rr", "tt") __li_ending = "cdeghkmnrt" __step0_suffixes = ("'s'", "'s", "'") __step1a_suffixes = ("sses", "ied", "ies", "us", "ss", "s") __step1b_suffixes = ("eedly", "ingly", "edly", "eed", "ing", "ed") __step2_suffixes = ('ization', 'ational', 'fulness', 'ousness', 'iveness', 'tional', 'biliti', 'lessli', 'entli', 'ation', 'alism', 'aliti', 'ousli', 'iviti', 'fulli', 'enci', 'anci', 'abli', 'izer', 'ator', 'alli', 'bli', 'ogi', 'li') __step3_suffixes = ('ational', 'tional', 'alize', 'icate', 'iciti', 'ative', 'ical', 'ness', 'ful') __step4_suffixes = ('ement', 'ance', 'ence', 'able', 'ible', 'ment', 'ant', 'ent', 'ism', 'ate', 'iti', 'ous', 'ive', 'ize', 'ion', 'al', 'er', 'ic') __step5_suffixes = ("e", "l") __special_words = {"skis" : "ski", "skies" : "sky", "dying" : "die", "lying" : "lie", "tying" : "tie", "idly" : "idl", "gently" : "gentl", "ugly" : "ugli", "early" : "earli", "only" : "onli", "singly" : "singl", "sky" : "sky", "news" : "news", "howe" : "howe", "atlas" : "atlas", "cosmos" : "cosmos", "bias" : "bias", "andes" : "andes", "inning" : "inning", "innings" : "inning", "outing" : "outing", "outings" : "outing", "canning" : "canning", "cannings" : "canning", "herring" : "herring", "herrings" : "herring", "earring" : "earring", "earrings" : "earring", "proceed" : "proceed", "proceeds" : "proceed", "proceeded" : "proceed", "proceeding" : "proceed", "exceed" : "exceed", "exceeds" : "exceed", "exceeded" : "exceed", "exceeding" : "exceed", "succeed" : "succeed", "succeeds" : "succeed", "succeeded" : "succeed", "succeeding" : "succeed"}
[docs] def stem(self, word): """ Stem an English word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords or len(word) <= 2: return word elif word in self.__special_words: return self.__special_words[word] # Map the different apostrophe characters to a single consistent one word = (word.replace("\u2019", "\x27") .replace("\u2018", "\x27") .replace("\u201B", "\x27")) if word.startswith("\x27"): word = word[1:] if word.startswith("y"): word = "".join(("Y", word[1:])) for i in range(1, len(word)): if word[i-1] in self.__vowels and word[i] == "y": word = "".join((word[:i], "Y", word[i+1:])) step1a_vowel_found = False step1b_vowel_found = False r1 = "" r2 = "" if word.startswith(("gener", "commun", "arsen")): if word.startswith(("gener", "arsen")): r1 = word[5:] else: r1 = word[6:] for i in range(1, len(r1)): if r1[i] not in self.__vowels and r1[i-1] in self.__vowels: r2 = r1[i+1:] break else: r1, r2 = self._r1r2_standard(word, self.__vowels) # STEP 0 for suffix in self.__step0_suffixes: if word.endswith(suffix): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 1a for suffix in self.__step1a_suffixes: if word.endswith(suffix): if suffix == "sses": word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix in ("ied", "ies"): if len(word[:-len(suffix)]) > 1: word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] else: word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] elif suffix == "s": for letter in word[:-2]: if letter in self.__vowels: step1a_vowel_found = True break if step1a_vowel_found: word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] break # STEP 1b for suffix in self.__step1b_suffixes: if word.endswith(suffix): if suffix in ("eed", "eedly"): if r1.endswith(suffix): word = suffix_replace(word, suffix, "ee") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ee") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ee") else: r2 = "" else: for letter in word[:-len(suffix)]: if letter in self.__vowels: step1b_vowel_found = True break if step1b_vowel_found: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] if word.endswith(("at", "bl", "iz")): word = "".join((word, "e")) r1 = "".join((r1, "e")) if len(word) > 5 or len(r1) >=3: r2 = "".join((r2, "e")) elif word.endswith(self.__double_consonants): word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] elif ((r1 == "" and len(word) >= 3 and word[-1] not in self.__vowels and word[-1] not in "wxY" and word[-2] in self.__vowels and word[-3] not in self.__vowels) or (r1 == "" and len(word) == 2 and word[0] in self.__vowels and word[1] not in self.__vowels)): word = "".join((word, "e")) if len(r1) > 0: r1 = "".join((r1, "e")) if len(r2) > 0: r2 = "".join((r2, "e")) break # STEP 1c if len(word) > 2 and word[-1] in "yY" and word[-2] not in self.__vowels: word = "".join((word[:-1], "i")) if len(r1) >= 1: r1 = "".join((r1[:-1], "i")) else: r1 = "" if len(r2) >= 1: r2 = "".join((r2[:-1], "i")) else: r2 = "" # STEP 2 for suffix in self.__step2_suffixes: if word.endswith(suffix): if r1.endswith(suffix): if suffix == "tional": word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix in ("enci", "anci", "abli"): word = "".join((word[:-1], "e")) if len(r1) >= 1: r1 = "".join((r1[:-1], "e")) else: r1 = "" if len(r2) >= 1: r2 = "".join((r2[:-1], "e")) else: r2 = "" elif suffix == "entli": word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix in ("izer", "ization"): word = suffix_replace(word, suffix, "ize") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ize") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ize") else: r2 = "" elif suffix in ("ational", "ation", "ator"): word = suffix_replace(word, suffix, "ate") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ate") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ate") else: r2 = "e" elif suffix in ("alism", "aliti", "alli"): word = suffix_replace(word, suffix, "al") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "al") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "al") else: r2 = "" elif suffix == "fulness": word = word[:-4] r1 = r1[:-4] r2 = r2[:-4] elif suffix in ("ousli", "ousness"): word = suffix_replace(word, suffix, "ous") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ous") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ous") else: r2 = "" elif suffix in ("iveness", "iviti"): word = suffix_replace(word, suffix, "ive") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ive") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ive") else: r2 = "e" elif suffix in ("biliti", "bli"): word = suffix_replace(word, suffix, "ble") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ble") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ble") else: r2 = "" elif suffix == "ogi" and word[-4] == "l": word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] elif suffix in ("fulli", "lessli"): word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix == "li" and word[-3] in self.__li_ending: word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] break # STEP 3 for suffix in self.__step3_suffixes: if word.endswith(suffix): if r1.endswith(suffix): if suffix == "tional": word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix == "ational": word = suffix_replace(word, suffix, "ate") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ate") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ate") else: r2 = "" elif suffix == "alize": word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] elif suffix in ("icate", "iciti", "ical"): word = suffix_replace(word, suffix, "ic") if len(r1) >= len(suffix): r1 = suffix_replace(r1, suffix, "ic") else: r1 = "" if len(r2) >= len(suffix): r2 = suffix_replace(r2, suffix, "ic") else: r2 = "" elif suffix in ("ful", "ness"): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] elif suffix == "ative" and r2.endswith(suffix): word = word[:-5] r1 = r1[:-5] r2 = r2[:-5] break # STEP 4 for suffix in self.__step4_suffixes: if word.endswith(suffix): if r2.endswith(suffix): if suffix == "ion": if word[-4] in "st": word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 5 if r2.endswith("l") and word[-2] == "l": word = word[:-1] elif r2.endswith("e"): word = word[:-1] elif r1.endswith("e"): if len(word) >= 4 and (word[-2] in self.__vowels or word[-2] in "wxY" or word[-3] not in self.__vowels or word[-4] in self.__vowels): word = word[:-1] word = word.replace("Y", "y") return word
[docs]class FinnishStemmer(_StandardStemmer): """ The Finnish Snowball stemmer. :cvar __vowels: The Finnish vowels. :type __vowels: unicode :cvar __restricted_vowels: A subset of the Finnish vowels. :type __restricted_vowels: unicode :cvar __long_vowels: The Finnish vowels in their long forms. :type __long_vowels: tuple :cvar __consonants: The Finnish consonants. :type __consonants: unicode :cvar __double_consonants: The Finnish double consonants. :type __double_consonants: tuple :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :cvar __step4_suffixes: Suffixes to be deleted in step 4 of the algorithm. :type __step4_suffixes: tuple :note: A detailed description of the Finnish stemming algorithm can be found under http://snowball.tartarus.org/algorithms/finnish/stemmer.html """ __vowels = "aeiouy\xE4\xF6" __restricted_vowels = "aeiou\xE4\xF6" __long_vowels = ("aa", "ee", "ii", "oo", "uu", "\xE4\xE4", "\xF6\xF6") __consonants = "bcdfghjklmnpqrstvwxz" __double_consonants = ("bb", "cc", "dd", "ff", "gg", "hh", "jj", "kk", "ll", "mm", "nn", "pp", "qq", "rr", "ss", "tt", "vv", "ww", "xx", "zz") __step1_suffixes = ('kaan', 'k\xE4\xE4n', 'sti', 'kin', 'han', 'h\xE4n', 'ko', 'k\xF6', 'pa', 'p\xE4') __step2_suffixes = ('nsa', 'ns\xE4', 'mme', 'nne', 'si', 'ni', 'an', '\xE4n', 'en') __step3_suffixes = ('siin', 'tten', 'seen', 'han', 'hen', 'hin', 'hon', 'h\xE4n', 'h\xF6n', 'den', 'tta', 'tt\xE4', 'ssa', 'ss\xE4', 'sta', 'st\xE4', 'lla', 'll\xE4', 'lta', 'lt\xE4', 'lle', 'ksi', 'ine', 'ta', 't\xE4', 'na', 'n\xE4', 'a', '\xE4', 'n') __step4_suffixes = ('impi', 'impa', 'imp\xE4', 'immi', 'imma', 'imm\xE4', 'mpi', 'mpa', 'mp\xE4', 'mmi', 'mma', 'mm\xE4', 'eja', 'ej\xE4')
[docs] def stem(self, word): """ Stem a Finnish word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step3_success = False r1, r2 = self._r1r2_standard(word, self.__vowels) # STEP 1: Particles etc. for suffix in self.__step1_suffixes: if r1.endswith(suffix): if suffix == "sti": if suffix in r2: word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] else: if word[-len(suffix)-1] in "ntaeiouy\xE4\xF6": word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 2: Possessives for suffix in self.__step2_suffixes: if r1.endswith(suffix): if suffix == "si": if word[-3] != "k": word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix == "ni": word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] if word.endswith("kse"): word = suffix_replace(word, "kse", "ksi") if r1.endswith("kse"): r1 = suffix_replace(r1, "kse", "ksi") if r2.endswith("kse"): r2 = suffix_replace(r2, "kse", "ksi") elif suffix == "an": if (word[-4:-2] in ("ta", "na") or word[-5:-2] in ("ssa", "sta", "lla", "lta")): word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix == "\xE4n": if (word[-4:-2] in ("t\xE4", "n\xE4") or word[-5:-2] in ("ss\xE4", "st\xE4", "ll\xE4", "lt\xE4")): word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] elif suffix == "en": if word[-5:-2] in ("lle", "ine"): word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] else: word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] break # STEP 3: Cases for suffix in self.__step3_suffixes: if r1.endswith(suffix): if suffix in ("han", "hen", "hin", "hon", "h\xE4n", "h\xF6n"): if ((suffix == "han" and word[-4] == "a") or (suffix == "hen" and word[-4] == "e") or (suffix == "hin" and word[-4] == "i") or (suffix == "hon" and word[-4] == "o") or (suffix == "h\xE4n" and word[-4] == "\xE4") or (suffix == "h\xF6n" and word[-4] == "\xF6")): word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] step3_success = True elif suffix in ("siin", "den", "tten"): if (word[-len(suffix)-1] == "i" and word[-len(suffix)-2] in self.__restricted_vowels): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] step3_success = True else: continue elif suffix == "seen": if word[-6:-4] in self.__long_vowels: word = word[:-4] r1 = r1[:-4] r2 = r2[:-4] step3_success = True else: continue elif suffix in ("a", "\xE4"): if word[-2] in self.__vowels and word[-3] in self.__consonants: word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] step3_success = True elif suffix in ("tta", "tt\xE4"): if word[-4] == "e": word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] step3_success = True elif suffix == "n": word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] step3_success = True if word[-2:] == "ie" or word[-2:] in self.__long_vowels: word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] step3_success = True break # STEP 4: Other endings for suffix in self.__step4_suffixes: if r2.endswith(suffix): if suffix in ("mpi", "mpa", "mp\xE4", "mmi", "mma", "mm\xE4"): if word[-5:-3] != "po": word = word[:-3] r1 = r1[:-3] r2 = r2[:-3] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 5: Plurals if step3_success and len(r1) >= 1 and r1[-1] in "ij": word = word[:-1] r1 = r1[:-1] elif (not step3_success and len(r1) >= 2 and r1[-1] == "t" and r1[-2] in self.__vowels): word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] if r2.endswith("imma"): word = word[:-4] r1 = r1[:-4] elif r2.endswith("mma") and r2[-5:-3] != "po": word = word[:-3] r1 = r1[:-3] # STEP 6: Tidying up if r1[-2:] in self.__long_vowels: word = word[:-1] r1 = r1[:-1] if (len(r1) >= 2 and r1[-2] in self.__consonants and r1[-1] in "a\xE4ei"): word = word[:-1] r1 = r1[:-1] if r1.endswith(("oj", "uj")): word = word[:-1] r1 = r1[:-1] if r1.endswith("jo"): word = word[:-1] r1 = r1[:-1] # If the word ends with a double consonant # followed by zero or more vowels, the last consonant is removed. for i in range(1, len(word)): if word[-i] in self.__vowels: continue else: if i == 1: if word[-i-1:] in self.__double_consonants: word = word[:-1] else: if word[-i-1:-i+1] in self.__double_consonants: word = "".join((word[:-i], word[-i+1:])) break return word
[docs]class FrenchStemmer(_StandardStemmer): """ The French Snowball stemmer. :cvar __vowels: The French vowels. :type __vowels: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2a_suffixes: Suffixes to be deleted in step 2a of the algorithm. :type __step2a_suffixes: tuple :cvar __step2b_suffixes: Suffixes to be deleted in step 2b of the algorithm. :type __step2b_suffixes: tuple :cvar __step4_suffixes: Suffixes to be deleted in step 4 of the algorithm. :type __step4_suffixes: tuple :note: A detailed description of the French stemming algorithm can be found under http://snowball.tartarus.org/algorithms/french/stemmer.html """ __vowels = "aeiouy\xE2\xE0\xEB\xE9\xEA\xE8\xEF\xEE\xF4\xFB\xF9" __step1_suffixes = ('issements', 'issement', 'atrices', 'atrice', 'ateurs', 'ations', 'logies', 'usions', 'utions', 'ements', 'amment', 'emment', 'ances', 'iqUes', 'ismes', 'ables', 'istes', 'ateur', 'ation', 'logie', 'usion', 'ution', 'ences', 'ement', 'euses', 'ments', 'ance', 'iqUe', 'isme', 'able', 'iste', 'ence', 'it\xE9s', 'ives', 'eaux', 'euse', 'ment', 'eux', 'it\xE9', 'ive', 'ifs', 'aux', 'if') __step2a_suffixes = ('issaIent', 'issantes', 'iraIent', 'issante', 'issants', 'issions', 'irions', 'issais', 'issait', 'issant', 'issent', 'issiez', 'issons', 'irais', 'irait', 'irent', 'iriez', 'irons', 'iront', 'isses', 'issez', '\xEEmes', '\xEEtes', 'irai', 'iras', 'irez', 'isse', 'ies', 'ira', '\xEEt', 'ie', 'ir', 'is', 'it', 'i') __step2b_suffixes = ('eraIent', 'assions', 'erions', 'assent', 'assiez', '\xE8rent', 'erais', 'erait', 'eriez', 'erons', 'eront', 'aIent', 'antes', 'asses', 'ions', 'erai', 'eras', 'erez', '\xE2mes', '\xE2tes', 'ante', 'ants', 'asse', '\xE9es', 'era', 'iez', 'ais', 'ait', 'ant', '\xE9e', '\xE9s', 'er', 'ez', '\xE2t', 'ai', 'as', '\xE9', 'a') __step4_suffixes = ('i\xE8re', 'I\xE8re', 'ion', 'ier', 'Ier', 'e', '\xEB')
[docs] def stem(self, word): """ Stem a French word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step1_success = False rv_ending_found = False step2a_success = False step2b_success = False # Every occurrence of 'u' after 'q' is put into upper case. for i in range(1, len(word)): if word[i-1] == "q" and word[i] == "u": word = "".join((word[:i], "U", word[i+1:])) # Every occurrence of 'u' and 'i' # between vowels is put into upper case. # Every occurrence of 'y' preceded or # followed by a vowel is also put into upper case. for i in range(1, len(word)-1): if word[i-1] in self.__vowels and word[i+1] in self.__vowels: if word[i] == "u": word = "".join((word[:i], "U", word[i+1:])) elif word[i] == "i": word = "".join((word[:i], "I", word[i+1:])) if word[i-1] in self.__vowels or word[i+1] in self.__vowels: if word[i] == "y": word = "".join((word[:i], "Y", word[i+1:])) r1, r2 = self._r1r2_standard(word, self.__vowels) rv = self.__rv_french(word, self.__vowels) # STEP 1: Standard suffix removal for suffix in self.__step1_suffixes: if word.endswith(suffix): if suffix == "eaux": word = word[:-1] step1_success = True elif suffix in ("euse", "euses"): if suffix in r2: word = word[:-len(suffix)] step1_success = True elif suffix in r1: word = suffix_replace(word, suffix, "eux") step1_success = True elif suffix in ("ement", "ements") and suffix in rv: word = word[:-len(suffix)] step1_success = True if word[-2:] == "iv" and "iv" in r2: word = word[:-2] if word[-2:] == "at" and "at" in r2: word = word[:-2] elif word[-3:] == "eus": if "eus" in r2: word = word[:-3] elif "eus" in r1: word = "".join((word[:-1], "x")) elif word[-3:] in ("abl", "iqU"): if "abl" in r2 or "iqU" in r2: word = word[:-3] elif word[-3:] in ("i\xE8r", "I\xE8r"): if "i\xE8r" in rv or "I\xE8r" in rv: word = "".join((word[:-3], "i")) elif suffix == "amment" and suffix in rv: word = suffix_replace(word, "amment", "ant") rv = suffix_replace(rv, "amment", "ant") rv_ending_found = True elif suffix == "emment" and suffix in rv: word = suffix_replace(word, "emment", "ent") rv_ending_found = True elif (suffix in ("ment", "ments") and suffix in rv and not rv.startswith(suffix) and rv[rv.rindex(suffix)-1] in self.__vowels): word = word[:-len(suffix)] rv = rv[:-len(suffix)] rv_ending_found = True elif suffix == "aux" and suffix in r1: word = "".join((word[:-2], "l")) step1_success = True elif (suffix in ("issement", "issements") and suffix in r1 and word[-len(suffix)-1] not in self.__vowels): word = word[:-len(suffix)] step1_success = True elif suffix in ("ance", "iqUe", "isme", "able", "iste", "eux", "ances", "iqUes", "ismes", "ables", "istes") and suffix in r2: word = word[:-len(suffix)] step1_success = True elif suffix in ("atrice", "ateur", "ation", "atrices", "ateurs", "ations") and suffix in r2: word = word[:-len(suffix)] step1_success = True if word[-2:] == "ic": if "ic" in r2: word = word[:-2] else: word = "".join((word[:-2], "iqU")) elif suffix in ("logie", "logies") and suffix in r2: word = suffix_replace(word, suffix, "log") step1_success = True elif (suffix in ("usion", "ution", "usions", "utions") and suffix in r2): word = suffix_replace(word, suffix, "u") step1_success = True elif suffix in ("ence", "ences") and suffix in r2: word = suffix_replace(word, suffix, "ent") step1_success = True elif suffix in ("it\xE9", "it\xE9s") and suffix in r2: word = word[:-len(suffix)] step1_success = True if word[-4:] == "abil": if "abil" in r2: word = word[:-4] else: word = "".join((word[:-2], "l")) elif word[-2:] == "ic": if "ic" in r2: word = word[:-2] else: word = "".join((word[:-2], "iqU")) elif word[-2:] == "iv": if "iv" in r2: word = word[:-2] elif (suffix in ("if", "ive", "ifs", "ives") and suffix in r2): word = word[:-len(suffix)] step1_success = True if word[-2:] == "at" and "at" in r2: word = word[:-2] if word[-2:] == "ic": if "ic" in r2: word = word[:-2] else: word = "".join((word[:-2], "iqU")) break # STEP 2a: Verb suffixes beginning 'i' if not step1_success or rv_ending_found: for suffix in self.__step2a_suffixes: if word.endswith(suffix): if (suffix in rv and len(rv) > len(suffix) and rv[rv.rindex(suffix)-1] not in self.__vowels): word = word[:-len(suffix)] step2a_success = True break # STEP 2b: Other verb suffixes if not step2a_success: for suffix in self.__step2b_suffixes: if rv.endswith(suffix): if suffix == "ions" and "ions" in r2: word = word[:-4] step2b_success = True elif suffix in ('eraIent', 'erions', '\xE8rent', 'erais', 'erait', 'eriez', 'erons', 'eront', 'erai', 'eras', 'erez', '\xE9es', 'era', 'iez', '\xE9e', '\xE9s', 'er', 'ez', '\xE9'): word = word[:-len(suffix)] step2b_success = True elif suffix in ('assions', 'assent', 'assiez', 'aIent', 'antes', 'asses', '\xE2mes', '\xE2tes', 'ante', 'ants', 'asse', 'ais', 'ait', 'ant', '\xE2t', 'ai', 'as', 'a'): word = word[:-len(suffix)] rv = rv[:-len(suffix)] step2b_success = True if rv.endswith("e"): word = word[:-1] break # STEP 3 if step1_success or step2a_success or step2b_success: if word[-1] == "Y": word = "".join((word[:-1], "i")) elif word[-1] == "\xE7": word = "".join((word[:-1], "c")) # STEP 4: Residual suffixes else: if (len(word) >= 2 and word[-1] == "s" and word[-2] not in "aiou\xE8s"): word = word[:-1] for suffix in self.__step4_suffixes: if word.endswith(suffix): if suffix in rv: if (suffix == "ion" and suffix in r2 and rv[-4] in "st"): word = word[:-3] elif suffix in ("ier", "i\xE8re", "Ier", "I\xE8re"): word = suffix_replace(word, suffix, "i") elif suffix == "e": word = word[:-1] elif suffix == "\xEB" and word[-3:-1] == "gu": word = word[:-1] break # STEP 5: Undouble if word.endswith(("enn", "onn", "ett", "ell", "eill")): word = word[:-1] # STEP 6: Un-accent for i in range(1, len(word)): if word[-i] not in self.__vowels: i += 1 else: if i != 1 and word[-i] in ("\xE9", "\xE8"): word = "".join((word[:-i], "e", word[-i+1:])) break word = (word.replace("I", "i") .replace("U", "u") .replace("Y", "y")) return word
def __rv_french(self, word, vowels): """ Return the region RV that is used by the French stemmer. If the word begins with two vowels, RV is the region after the third letter. Otherwise, it is the region after the first vowel not at the beginning of the word, or the end of the word if these positions cannot be found. (Exceptionally, u'par', u'col' or u'tap' at the beginning of a word is also taken to define RV as the region to their right.) :param word: The French word whose region RV is determined. :type word: str or unicode :param vowels: The French vowels that are used to determine the region RV. :type vowels: unicode :return: the region RV for the respective French word. :rtype: unicode :note: This helper method is invoked by the stem method of the subclass FrenchStemmer. It is not to be invoked directly! """ rv = "" if len(word) >= 2: if (word.startswith(("par", "col", "tap")) or (word[0] in vowels and word[1] in vowels)): rv = word[3:] else: for i in range(1, len(word)): if word[i] in vowels: rv = word[i+1:] break return rv
[docs]class GermanStemmer(_StandardStemmer): """ The German Snowball stemmer. :cvar __vowels: The German vowels. :type __vowels: unicode :cvar __s_ending: Letters that may directly appear before a word final 's'. :type __s_ending: unicode :cvar __st_ending: Letter that may directly appear before a word final 'st'. :type __st_ending: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :note: A detailed description of the German stemming algorithm can be found under http://snowball.tartarus.org/algorithms/german/stemmer.html """ __vowels = "aeiouy\xE4\xF6\xFC" __s_ending = "bdfghklmnrt" __st_ending = "bdfghklmnt" __step1_suffixes = ("ern", "em", "er", "en", "es", "e", "s") __step2_suffixes = ("est", "en", "er", "st") __step3_suffixes = ("isch", "lich", "heit", "keit", "end", "ung", "ig", "ik")
[docs] def stem(self, word): """ Stem a German word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word word = word.replace("\xDF", "ss") # Every occurrence of 'u' and 'y' # between vowels is put into upper case. for i in range(1, len(word)-1): if word[i-1] in self.__vowels and word[i+1] in self.__vowels: if word[i] == "u": word = "".join((word[:i], "U", word[i+1:])) elif word[i] == "y": word = "".join((word[:i], "Y", word[i+1:])) r1, r2 = self._r1r2_standard(word, self.__vowels) # R1 is adjusted so that the region before it # contains at least 3 letters. for i in range(1, len(word)): if word[i] not in self.__vowels and word[i-1] in self.__vowels: if len(word[:i+1]) < 3 and len(word[:i+1]) > 0: r1 = word[3:] elif len(word[:i+1]) == 0: return word break # STEP 1 for suffix in self.__step1_suffixes: if r1.endswith(suffix): if (suffix in ("en", "es", "e") and word[-len(suffix)-4:-len(suffix)] == "niss"): word = word[:-len(suffix)-1] r1 = r1[:-len(suffix)-1] r2 = r2[:-len(suffix)-1] elif suffix == "s": if word[-2] in self.__s_ending: word = word[:-1] r1 = r1[:-1] r2 = r2[:-1] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 2 for suffix in self.__step2_suffixes: if r1.endswith(suffix): if suffix == "st": if word[-3] in self.__st_ending and len(word[:-3]) >= 3: word = word[:-2] r1 = r1[:-2] r2 = r2[:-2] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] break # STEP 3: Derivational suffixes for suffix in self.__step3_suffixes: if r2.endswith(suffix): if suffix in ("end", "ung"): if ("ig" in r2[-len(suffix)-2:-len(suffix)] and "e" not in r2[-len(suffix)-3:-len(suffix)-2]): word = word[:-len(suffix)-2] else: word = word[:-len(suffix)] elif (suffix in ("ig", "ik", "isch") and "e" not in r2[-len(suffix)-1:-len(suffix)]): word = word[:-len(suffix)] elif suffix in ("lich", "heit"): if ("er" in r1[-len(suffix)-2:-len(suffix)] or "en" in r1[-len(suffix)-2:-len(suffix)]): word = word[:-len(suffix)-2] else: word = word[:-len(suffix)] elif suffix == "keit": if "lich" in r2[-len(suffix)-4:-len(suffix)]: word = word[:-len(suffix)-4] elif "ig" in r2[-len(suffix)-2:-len(suffix)]: word = word[:-len(suffix)-2] else: word = word[:-len(suffix)] break # Umlaut accents are removed and # 'u' and 'y' are put back into lower case. word = (word.replace("\xE4", "a").replace("\xF6", "o") .replace("\xFC", "u").replace("U", "u") .replace("Y", "y")) return word
[docs]class HungarianStemmer(_LanguageSpecificStemmer): """ The Hungarian Snowball stemmer. :cvar __vowels: The Hungarian vowels. :type __vowels: unicode :cvar __digraphs: The Hungarian digraphs. :type __digraphs: tuple :cvar __double_consonants: The Hungarian double consonants. :type __double_consonants: tuple :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :cvar __step4_suffixes: Suffixes to be deleted in step 4 of the algorithm. :type __step4_suffixes: tuple :cvar __step5_suffixes: Suffixes to be deleted in step 5 of the algorithm. :type __step5_suffixes: tuple :cvar __step6_suffixes: Suffixes to be deleted in step 6 of the algorithm. :type __step6_suffixes: tuple :cvar __step7_suffixes: Suffixes to be deleted in step 7 of the algorithm. :type __step7_suffixes: tuple :cvar __step8_suffixes: Suffixes to be deleted in step 8 of the algorithm. :type __step8_suffixes: tuple :cvar __step9_suffixes: Suffixes to be deleted in step 9 of the algorithm. :type __step9_suffixes: tuple :note: A detailed description of the Hungarian stemming algorithm can be found under http://snowball.tartarus.org/algorithms/hungarian/stemmer.html """ __vowels = "aeiou\xF6\xFC\xE1\xE9\xED\xF3\xF5\xFA\xFB" __digraphs = ("cs", "dz", "dzs", "gy", "ly", "ny", "ty", "zs") __double_consonants = ("bb", "cc", "ccs", "dd", "ff", "gg", "ggy", "jj", "kk", "ll", "lly", "mm", "nn", "nny", "pp", "rr", "ss", "ssz", "tt", "tty", "vv", "zz", "zzs") __step1_suffixes = ("al", "el") __step2_suffixes = ('k\xE9ppen', 'onk\xE9nt', 'enk\xE9nt', 'ank\xE9nt', 'k\xE9pp', 'k\xE9nt', 'ban', 'ben', 'nak', 'nek', 'val', 'vel', 't\xF3l', 't\xF5l', 'r\xF3l', 'r\xF5l', 'b\xF3l', 'b\xF5l', 'hoz', 'hez', 'h\xF6z', 'n\xE1l', 'n\xE9l', '\xE9rt', 'kor', 'ba', 'be', 'ra', 're', 'ig', 'at', 'et', 'ot', '\xF6t', 'ul', '\xFCl', 'v\xE1', 'v\xE9', 'en', 'on', 'an', '\xF6n', 'n', 't') __step3_suffixes = ("\xE1nk\xE9nt", "\xE1n", "\xE9n") __step4_suffixes = ('astul', 'est\xFCl', '\xE1stul', '\xE9st\xFCl', 'stul', 'st\xFCl') __step5_suffixes = ("\xE1", "\xE9") __step6_suffixes = ('ok\xE9', '\xF6k\xE9', 'ak\xE9', 'ek\xE9', '\xE1k\xE9', '\xE1\xE9i', '\xE9k\xE9', '\xE9\xE9i', 'k\xE9', '\xE9i', '\xE9\xE9', '\xE9') __step7_suffixes = ('\xE1juk', '\xE9j\xFCk', '\xFCnk', 'unk', 'juk', 'j\xFCk', '\xE1nk', '\xE9nk', 'nk', 'uk', '\xFCk', 'em', 'om', 'am', 'od', 'ed', 'ad', '\xF6d', 'ja', 'je', '\xE1m', '\xE1d', '\xE9m', '\xE9d', 'm', 'd', 'a', 'e', 'o', '\xE1', '\xE9') __step8_suffixes = ('jaitok', 'jeitek', 'jaink', 'jeink', 'aitok', 'eitek', '\xE1itok', '\xE9itek', 'jaim', 'jeim', 'jaid', 'jeid', 'eink', 'aink', 'itek', 'jeik', 'jaik', '\xE1ink', '\xE9ink', 'aim', 'eim', 'aid', 'eid', 'jai', 'jei', 'ink', 'aik', 'eik', '\xE1im', '\xE1id', '\xE1ik', '\xE9im', '\xE9id', '\xE9ik', 'im', 'id', 'ai', 'ei', 'ik', '\xE1i', '\xE9i', 'i') __step9_suffixes = ("\xE1k", "\xE9k", "\xF6k", "ok", "ek", "ak", "k")
[docs] def stem(self, word): """ Stem an Hungarian word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word r1 = self.__r1_hungarian(word, self.__vowels, self.__digraphs) # STEP 1: Remove instrumental case if r1.endswith(self.__step1_suffixes): for double_cons in self.__double_consonants: if word[-2-len(double_cons):-2] == double_cons: word = "".join((word[:-4], word[-3])) if r1[-2-len(double_cons):-2] == double_cons: r1 = "".join((r1[:-4], r1[-3])) break # STEP 2: Remove frequent cases for suffix in self.__step2_suffixes: if word.endswith(suffix): if r1.endswith(suffix): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] if r1.endswith("\xE1"): word = "".join((word[:-1], "a")) r1 = suffix_replace(r1, "\xE1", "a") elif r1.endswith("\xE9"): word = "".join((word[:-1], "e")) r1 = suffix_replace(r1, "\xE9", "e") break # STEP 3: Remove special cases for suffix in self.__step3_suffixes: if r1.endswith(suffix): if suffix == "\xE9n": word = suffix_replace(word, suffix, "e") r1 = suffix_replace(r1, suffix, "e") else: word = suffix_replace(word, suffix, "a") r1 = suffix_replace(r1, suffix, "a") break # STEP 4: Remove other cases for suffix in self.__step4_suffixes: if r1.endswith(suffix): if suffix == "\xE1stul": word = suffix_replace(word, suffix, "a") r1 = suffix_replace(r1, suffix, "a") elif suffix == "\xE9st\xFCl": word = suffix_replace(word, suffix, "e") r1 = suffix_replace(r1, suffix, "e") else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 5: Remove factive case for suffix in self.__step5_suffixes: if r1.endswith(suffix): for double_cons in self.__double_consonants: if word[-1-len(double_cons):-1] == double_cons: word = "".join((word[:-3], word[-2])) if r1[-1-len(double_cons):-1] == double_cons: r1 = "".join((r1[:-3], r1[-2])) break # STEP 6: Remove owned for suffix in self.__step6_suffixes: if r1.endswith(suffix): if suffix in ("\xE1k\xE9", "\xE1\xE9i"): word = suffix_replace(word, suffix, "a") r1 = suffix_replace(r1, suffix, "a") elif suffix in ("\xE9k\xE9", "\xE9\xE9i", "\xE9\xE9"): word = suffix_replace(word, suffix, "e") r1 = suffix_replace(r1, suffix, "e") else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 7: Remove singular owner suffixes for suffix in self.__step7_suffixes: if word.endswith(suffix): if r1.endswith(suffix): if suffix in ("\xE1nk", "\xE1juk", "\xE1m", "\xE1d", "\xE1"): word = suffix_replace(word, suffix, "a") r1 = suffix_replace(r1, suffix, "a") elif suffix in ("\xE9nk", "\xE9j\xFCk", "\xE9m", "\xE9d", "\xE9"): word = suffix_replace(word, suffix, "e") r1 = suffix_replace(r1, suffix, "e") else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 8: Remove plural owner suffixes for suffix in self.__step8_suffixes: if word.endswith(suffix): if r1.endswith(suffix): if suffix in ("\xE1im", "\xE1id", "\xE1i", "\xE1ink", "\xE1itok", "\xE1ik"): word = suffix_replace(word, suffix, "a") r1 = suffix_replace(r1, suffix, "a") elif suffix in ("\xE9im", "\xE9id", "\xE9i", "\xE9ink", "\xE9itek", "\xE9ik"): word = suffix_replace(word, suffix, "e") r1 = suffix_replace(r1, suffix, "e") else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 9: Remove plural suffixes for suffix in self.__step9_suffixes: if word.endswith(suffix): if r1.endswith(suffix): if suffix == "\xE1k": word = suffix_replace(word, suffix, "a") elif suffix == "\xE9k": word = suffix_replace(word, suffix, "e") else: word = word[:-len(suffix)] break return word
def __r1_hungarian(self, word, vowels, digraphs): """ Return the region R1 that is used by the Hungarian stemmer. If the word begins with a vowel, R1 is defined as the region after the first consonant or digraph (= two letters stand for one phoneme) in the word. If the word begins with a consonant, it is defined as the region after the first vowel in the word. If the word does not contain both a vowel and consonant, R1 is the null region at the end of the word. :param word: The Hungarian word whose region R1 is determined. :type word: str or unicode :param vowels: The Hungarian vowels that are used to determine the region R1. :type vowels: unicode :param digraphs: The digraphs that are used to determine the region R1. :type digraphs: tuple :return: the region R1 for the respective word. :rtype: unicode :note: This helper method is invoked by the stem method of the subclass HungarianStemmer. It is not to be invoked directly! """ r1 = "" if word[0] in vowels: for digraph in digraphs: if digraph in word[1:]: r1 = word[word.index(digraph[-1])+1:] return r1 for i in range(1, len(word)): if word[i] not in vowels: r1 = word[i+1:] break else: for i in range(1, len(word)): if word[i] in vowels: r1 = word[i+1:] break return r1
[docs]class ItalianStemmer(_StandardStemmer): """ The Italian Snowball stemmer. :cvar __vowels: The Italian vowels. :type __vowels: unicode :cvar __step0_suffixes: Suffixes to be deleted in step 0 of the algorithm. :type __step0_suffixes: tuple :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :note: A detailed description of the Italian stemming algorithm can be found under http://snowball.tartarus.org/algorithms/italian/stemmer.html """ __vowels = "aeiou\xE0\xE8\xEC\xF2\xF9" __step0_suffixes = ('gliela', 'gliele', 'glieli', 'glielo', 'gliene', 'sene', 'mela', 'mele', 'meli', 'melo', 'mene', 'tela', 'tele', 'teli', 'telo', 'tene', 'cela', 'cele', 'celi', 'celo', 'cene', 'vela', 'vele', 'veli', 'velo', 'vene', 'gli', 'ci', 'la', 'le', 'li', 'lo', 'mi', 'ne', 'si', 'ti', 'vi') __step1_suffixes = ('atrice', 'atrici', 'azione', 'azioni', 'uzione', 'uzioni', 'usione', 'usioni', 'amento', 'amenti', 'imento', 'imenti', 'amente', 'abile', 'abili', 'ibile', 'ibili', 'mente', 'atore', 'atori', 'logia', 'logie', 'anza', 'anze', 'iche', 'ichi', 'ismo', 'ismi', 'ista', 'iste', 'isti', 'ist\xE0', 'ist\xE8', 'ist\xEC', 'ante', 'anti', 'enza', 'enze', 'ico', 'ici', 'ica', 'ice', 'oso', 'osi', 'osa', 'ose', 'it\xE0', 'ivo', 'ivi', 'iva', 'ive') __step2_suffixes = ('erebbero', 'irebbero', 'assero', 'assimo', 'eranno', 'erebbe', 'eremmo', 'ereste', 'eresti', 'essero', 'iranno', 'irebbe', 'iremmo', 'ireste', 'iresti', 'iscano', 'iscono', 'issero', 'arono', 'avamo', 'avano', 'avate', 'eremo', 'erete', 'erono', 'evamo', 'evano', 'evate', 'iremo', 'irete', 'irono', 'ivamo', 'ivano', 'ivate', 'ammo', 'ando', 'asse', 'assi', 'emmo', 'enda', 'ende', 'endi', 'endo', 'erai', 'erei', 'Yamo', 'iamo', 'immo', 'irai', 'irei', 'isca', 'isce', 'isci', 'isco', 'ano', 'are', 'ata', 'ate', 'ati', 'ato', 'ava', 'avi', 'avo', 'er\xE0', 'ere', 'er\xF2', 'ete', 'eva', 'evi', 'evo', 'ir\xE0', 'ire', 'ir\xF2', 'ita', 'ite', 'iti', 'ito', 'iva', 'ivi', 'ivo', 'ono', 'uta', 'ute', 'uti', 'uto', 'ar', 'ir')
[docs] def stem(self, word): """ Stem an Italian word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step1_success = False # All acute accents are replaced by grave accents. word = (word.replace("\xE1", "\xE0") .replace("\xE9", "\xE8") .replace("\xED", "\xEC") .replace("\xF3", "\xF2") .replace("\xFA", "\xF9")) # Every occurrence of 'u' after 'q' # is put into upper case. for i in range(1, len(word)): if word[i-1] == "q" and word[i] == "u": word = "".join((word[:i], "U", word[i+1:])) # Every occurrence of 'u' and 'i' # between vowels is put into upper case. for i in range(1, len(word)-1): if word[i-1] in self.__vowels and word[i+1] in self.__vowels: if word[i] == "u": word = "".join((word[:i], "U", word[i+1:])) elif word [i] == "i": word = "".join((word[:i], "I", word[i+1:])) r1, r2 = self._r1r2_standard(word, self.__vowels) rv = self._rv_standard(word, self.__vowels) # STEP 0: Attached pronoun for suffix in self.__step0_suffixes: if rv.endswith(suffix): if rv[-len(suffix)-4:-len(suffix)] in ("ando", "endo"): word = word[:-len(suffix)] r1 = r1[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] elif (rv[-len(suffix)-2:-len(suffix)] in ("ar", "er", "ir")): word = suffix_replace(word, suffix, "e") r1 = suffix_replace(r1, suffix, "e") r2 = suffix_replace(r2, suffix, "e") rv = suffix_replace(rv, suffix, "e") break # STEP 1: Standard suffix removal for suffix in self.__step1_suffixes: if word.endswith(suffix): if suffix == "amente" and r1.endswith(suffix): step1_success = True word = word[:-6] r2 = r2[:-6] rv = rv[:-6] if r2.endswith("iv"): word = word[:-2] r2 = r2[:-2] rv = rv[:-2] if r2.endswith("at"): word = word[:-2] rv = rv[:-2] elif r2.endswith(("os", "ic")): word = word[:-2] rv = rv[:-2] elif r2 .endswith("abil"): word = word[:-4] rv = rv[:-4] elif (suffix in ("amento", "amenti", "imento", "imenti") and rv.endswith(suffix)): step1_success = True word = word[:-6] rv = rv[:-6] elif r2.endswith(suffix): step1_success = True if suffix in ("azione", "azioni", "atore", "atori"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] if r2.endswith("ic"): word = word[:-2] rv = rv[:-2] elif suffix in ("logia", "logie"): word = word[:-2] rv = word[:-2] elif suffix in ("uzione", "uzioni", "usione", "usioni"): word = word[:-5] rv = rv[:-5] elif suffix in ("enza", "enze"): word = suffix_replace(word, suffix, "te") rv = suffix_replace(rv, suffix, "te") elif suffix == "it\xE0": word = word[:-3] r2 = r2[:-3] rv = rv[:-3] if r2.endswith(("ic", "iv")): word = word[:-2] rv = rv[:-2] elif r2.endswith("abil"): word = word[:-4] rv = rv[:-4] elif suffix in ("ivo", "ivi", "iva", "ive"): word = word[:-3] r2 = r2[:-3] rv = rv[:-3] if r2.endswith("at"): word = word[:-2] r2 = r2[:-2] rv = rv[:-2] if r2.endswith("ic"): word = word[:-2] rv = rv[:-2] else: word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 2: Verb suffixes if not step1_success: for suffix in self.__step2_suffixes: if rv.endswith(suffix): word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 3a if rv.endswith(("a", "e", "i", "o", "\xE0", "\xE8", "\xEC", "\xF2")): word = word[:-1] rv = rv[:-1] if rv.endswith("i"): word = word[:-1] rv = rv[:-1] # STEP 3b if rv.endswith(("ch", "gh")): word = word[:-1] word = word.replace("I", "i").replace("U", "u") return word
[docs]class NorwegianStemmer(_ScandinavianStemmer): """ The Norwegian Snowball stemmer. :cvar __vowels: The Norwegian vowels. :type __vowels: unicode :cvar __s_ending: Letters that may directly appear before a word final 's'. :type __s_ending: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :note: A detailed description of the Norwegian stemming algorithm can be found under http://snowball.tartarus.org/algorithms/norwegian/stemmer.html """ __vowels = "aeiouy\xE6\xE5\xF8" __s_ending = "bcdfghjlmnoprtvyz" __step1_suffixes = ("hetenes", "hetene", "hetens", "heter", "heten", "endes", "ande", "ende", "edes", "enes", "erte", "ede", "ane", "ene", "ens", "ers", "ets", "het", "ast", "ert", "en", "ar", "er", "as", "es", "et", "a", "e", "s") __step2_suffixes = ("dt", "vt") __step3_suffixes = ("hetslov", "eleg", "elig", "elov", "slov", "leg", "eig", "lig", "els", "lov", "ig")
[docs] def stem(self, word): """ Stem a Norwegian word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word r1 = self._r1_scandinavian(word, self.__vowels) # STEP 1 for suffix in self.__step1_suffixes: if r1.endswith(suffix): if suffix in ("erte", "ert"): word = suffix_replace(word, suffix, "er") r1 = suffix_replace(r1, suffix, "er") elif suffix == "s": if (word[-2] in self.__s_ending or (word[-2] == "k" and word[-3] not in self.__vowels)): word = word[:-1] r1 = r1[:-1] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 2 for suffix in self.__step2_suffixes: if r1.endswith(suffix): word = word[:-1] r1 = r1[:-1] break # STEP 3 for suffix in self.__step3_suffixes: if r1.endswith(suffix): word = word[:-len(suffix)] break return word
[docs]class PortugueseStemmer(_StandardStemmer): """ The Portuguese Snowball stemmer. :cvar __vowels: The Portuguese vowels. :type __vowels: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step4_suffixes: Suffixes to be deleted in step 4 of the algorithm. :type __step4_suffixes: tuple :note: A detailed description of the Portuguese stemming algorithm can be found under http://snowball.tartarus.org/algorithms/portuguese/stemmer.html """ __vowels = "aeiou\xE1\xE9\xED\xF3\xFA\xE2\xEA\xF4" __step1_suffixes = ('amentos', 'imentos', 'uço~es', 'amento', 'imento', 'adoras', 'adores', 'a\xE7o~es', 'logias', '\xEAncias', 'amente', 'idades', 'an\xE7as', 'ismos', 'istas', 'adora', 'a\xE7a~o', 'antes', '\xE2ncia', 'logia', 'uça~o', '\xEAncia', 'mente', 'idade', 'an\xE7a', 'ezas', 'icos', 'icas', 'ismo', '\xE1vel', '\xEDvel', 'ista', 'osos', 'osas', 'ador', 'ante', 'ivas', 'ivos', 'iras', 'eza', 'ico', 'ica', 'oso', 'osa', 'iva', 'ivo', 'ira') __step2_suffixes = ('ar\xEDamos', 'er\xEDamos', 'ir\xEDamos', '\xE1ssemos', '\xEAssemos', '\xEDssemos', 'ar\xEDeis', 'er\xEDeis', 'ir\xEDeis', '\xE1sseis', '\xE9sseis', '\xEDsseis', '\xE1ramos', '\xE9ramos', '\xEDramos', '\xE1vamos', 'aremos', 'eremos', 'iremos', 'ariam', 'eriam', 'iriam', 'assem', 'essem', 'issem', 'ara~o', 'era~o', 'ira~o', 'arias', 'erias', 'irias', 'ardes', 'erdes', 'irdes', 'asses', 'esses', 'isses', 'astes', 'estes', 'istes', '\xE1reis', 'areis', '\xE9reis', 'ereis', '\xEDreis', 'ireis', '\xE1veis', '\xEDamos', 'armos', 'ermos', 'irmos', 'aria', 'eria', 'iria', 'asse', 'esse', 'isse', 'aste', 'este', 'iste', 'arei', 'erei', 'irei', 'aram', 'eram', 'iram', 'avam', 'arem', 'erem', 'irem', 'ando', 'endo', 'indo', 'adas', 'idas', 'ar\xE1s', 'aras', 'er\xE1s', 'eras', 'ir\xE1s', 'avas', 'ares', 'eres', 'ires', '\xEDeis', 'ados', 'idos', '\xE1mos', 'amos', 'emos', 'imos', 'iras', 'ada', 'ida', 'ar\xE1', 'ara', 'er\xE1', 'era', 'ir\xE1', 'ava', 'iam', 'ado', 'ido', 'ias', 'ais', 'eis', 'ira', 'ia', 'ei', 'am', 'em', 'ar', 'er', 'ir', 'as', 'es', 'is', 'eu', 'iu', 'ou') __step4_suffixes = ("os", "a", "i", "o", "\xE1", "\xED", "\xF3")
[docs] def stem(self, word): """ Stem a Portuguese word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step1_success = False step2_success = False word = (word.replace("\xE3", "a~") .replace("\xF5", "o~") .replace("q\xFC", "qu") .replace("g\xFC", "gu")) r1, r2 = self._r1r2_standard(word, self.__vowels) rv = self._rv_standard(word, self.__vowels) # STEP 1: Standard suffix removal for suffix in self.__step1_suffixes: if word.endswith(suffix): if suffix == "amente" and r1.endswith(suffix): step1_success = True word = word[:-6] r2 = r2[:-6] rv = rv[:-6] if r2.endswith("iv"): word = word[:-2] r2 = r2[:-2] rv = rv[:-2] if r2.endswith("at"): word = word[:-2] rv = rv[:-2] elif r2.endswith(("os", "ic", "ad")): word = word[:-2] rv = rv[:-2] elif (suffix in ("ira", "iras") and rv.endswith(suffix) and word[-len(suffix)-1:-len(suffix)] == "e"): step1_success = True word = suffix_replace(word, suffix, "ir") rv = suffix_replace(rv, suffix, "ir") elif r2.endswith(suffix): step1_success = True if suffix in ("logia", "logias"): word = suffix_replace(word, suffix, "log") rv = suffix_replace(rv, suffix, "log") elif suffix in ("uça~o", "uço~es"): word = suffix_replace(word, suffix, "u") rv = suffix_replace(rv, suffix, "u") elif suffix in ("\xEAncia", "\xEAncias"): word = suffix_replace(word, suffix, "ente") rv = suffix_replace(rv, suffix, "ente") elif suffix == "mente": word = word[:-5] r2 = r2[:-5] rv = rv[:-5] if r2.endswith(("ante", "avel", "ivel")): word = word[:-4] rv = rv[:-4] elif suffix in ("idade", "idades"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] if r2.endswith(("ic", "iv")): word = word[:-2] rv = rv[:-2] elif r2.endswith("abil"): word = word[:-4] rv = rv[:-4] elif suffix in ("iva", "ivo", "ivas", "ivos"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] if r2.endswith("at"): word = word[:-2] rv = rv[:-2] else: word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 2: Verb suffixes if not step1_success: for suffix in self.__step2_suffixes: if rv.endswith(suffix): step2_success = True word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 3 if step1_success or step2_success: if rv.endswith("i") and word[-2] == "c": word = word[:-1] rv = rv[:-1] ### STEP 4: Residual suffix if not step1_success and not step2_success: for suffix in self.__step4_suffixes: if rv.endswith(suffix): word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 5 if rv.endswith(("e", "\xE9", "\xEA")): word = word[:-1] rv = rv[:-1] if ((word.endswith("gu") and rv.endswith("u")) or (word.endswith("ci") and rv.endswith("i"))): word = word[:-1] elif word.endswith("\xE7"): word = suffix_replace(word, "\xE7", "c") word = word.replace("a~", "\xE3").replace("o~", "\xF5") return word
[docs]class RomanianStemmer(_StandardStemmer): """ The Romanian Snowball stemmer. :cvar __vowels: The Romanian vowels. :type __vowels: unicode :cvar __step0_suffixes: Suffixes to be deleted in step 0 of the algorithm. :type __step0_suffixes: tuple :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :note: A detailed description of the Romanian stemming algorithm can be found under http://snowball.tartarus.org/algorithms/romanian/stemmer.html """ __vowels = "aeiou\u0103\xE2\xEE" __step0_suffixes = ('iilor', 'ului', 'elor', 'iile', 'ilor', 'atei', 'a\u0163ie', 'a\u0163ia', 'aua', 'ele', 'iua', 'iei', 'ile', 'ul', 'ea', 'ii') __step1_suffixes = ('abilitate', 'abilitati', 'abilit\u0103\u0163i', 'ibilitate', 'abilit\u0103i', 'ivitate', 'ivitati', 'ivit\u0103\u0163i', 'icitate', 'icitati', 'icit\u0103\u0163i', 'icatori', 'ivit\u0103i', 'icit\u0103i', 'icator', 'a\u0163iune', 'atoare', '\u0103toare', 'i\u0163iune', 'itoare', 'iciva', 'icive', 'icivi', 'iciv\u0103', 'icala', 'icale', 'icali', 'ical\u0103', 'ativa', 'ative', 'ativi', 'ativ\u0103', 'atori', '\u0103tori', 'itiva', 'itive', 'itivi', 'itiv\u0103', 'itori', 'iciv', 'ical', 'ativ', 'ator', '\u0103tor', 'itiv', 'itor') __step2_suffixes = ('abila', 'abile', 'abili', 'abil\u0103', 'ibila', 'ibile', 'ibili', 'ibil\u0103', 'atori', 'itate', 'itati', 'it\u0103\u0163i', 'abil', 'ibil', 'oasa', 'oas\u0103', 'oase', 'anta', 'ante', 'anti', 'ant\u0103', 'ator', 'it\u0103i', 'iune', 'iuni', 'isme', 'ista', 'iste', 'isti', 'ist\u0103', 'i\u015Fti', 'ata', 'at\u0103', 'ati', 'ate', 'uta', 'ut\u0103', 'uti', 'ute', 'ita', 'it\u0103', 'iti', 'ite', 'ica', 'ice', 'ici', 'ic\u0103', 'osi', 'o\u015Fi', 'ant', 'iva', 'ive', 'ivi', 'iv\u0103', 'ism', 'ist', 'at', 'ut', 'it', 'ic', 'os', 'iv') __step3_suffixes = ('seser\u0103\u0163i', 'aser\u0103\u0163i', 'iser\u0103\u0163i', '\xE2ser\u0103\u0163i', 'user\u0103\u0163i', 'seser\u0103m', 'aser\u0103m', 'iser\u0103m', '\xE2ser\u0103m', 'user\u0103m', 'ser\u0103\u0163i', 'sese\u015Fi', 'seser\u0103', 'easc\u0103', 'ar\u0103\u0163i', 'ur\u0103\u0163i', 'ir\u0103\u0163i', '\xE2r\u0103\u0163i', 'ase\u015Fi', 'aser\u0103', 'ise\u015Fi', 'iser\u0103', '\xe2se\u015Fi', '\xE2ser\u0103', 'use\u015Fi', 'user\u0103', 'ser\u0103m', 'sesem', 'indu', '\xE2ndu', 'eaz\u0103', 'e\u015Fti', 'e\u015Fte', '\u0103\u015Fti', '\u0103\u015Fte', 'ea\u0163i', 'ia\u0163i', 'ar\u0103m', 'ur\u0103m', 'ir\u0103m', '\xE2r\u0103m', 'asem', 'isem', '\xE2sem', 'usem', 'se\u015Fi', 'ser\u0103', 'sese', 'are', 'ere', 'ire', '\xE2re', 'ind', '\xE2nd', 'eze', 'ezi', 'esc', '\u0103sc', 'eam', 'eai', 'eau', 'iam', 'iai', 'iau', 'a\u015Fi', 'ar\u0103', 'u\u015Fi', 'ur\u0103', 'i\u015Fi', 'ir\u0103', '\xE2\u015Fi', '\xe2r\u0103', 'ase', 'ise', '\xE2se', 'use', 'a\u0163i', 'e\u0163i', 'i\u0163i', '\xe2\u0163i', 'sei', 'ez', 'am', 'ai', 'au', 'ea', 'ia', 'ui', '\xE2i', '\u0103m', 'em', 'im', '\xE2m', 'se')
[docs] def stem(self, word): """ Stem a Romanian word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step1_success = False step2_success = False for i in range(1, len(word)-1): if word[i-1] in self.__vowels and word[i+1] in self.__vowels: if word[i] == "u": word = "".join((word[:i], "U", word[i+1:])) elif word[i] == "i": word = "".join((word[:i], "I", word[i+1:])) r1, r2 = self._r1r2_standard(word, self.__vowels) rv = self._rv_standard(word, self.__vowels) # STEP 0: Removal of plurals and other simplifications for suffix in self.__step0_suffixes: if word.endswith(suffix): if suffix in r1: if suffix in ("ul", "ului"): word = word[:-len(suffix)] if suffix in rv: rv = rv[:-len(suffix)] else: rv = "" elif (suffix == "aua" or suffix == "atei" or (suffix == "ile" and word[-5:-3] != "ab")): word = word[:-2] elif suffix in ("ea", "ele", "elor"): word = suffix_replace(word, suffix, "e") if suffix in rv: rv = suffix_replace(rv, suffix, "e") else: rv = "" elif suffix in ("ii", "iua", "iei", "iile", "iilor", "ilor"): word = suffix_replace(word, suffix, "i") if suffix in rv: rv = suffix_replace(rv, suffix, "i") else: rv = "" elif suffix in ("a\u0163ie", "a\u0163ia"): word = word[:-1] break # STEP 1: Reduction of combining suffixes while True: replacement_done = False for suffix in self.__step1_suffixes: if word.endswith(suffix): if suffix in r1: step1_success = True replacement_done = True if suffix in ("abilitate", "abilitati", "abilit\u0103i", "abilit\u0103\u0163i"): word = suffix_replace(word, suffix, "abil") elif suffix == "ibilitate": word = word[:-5] elif suffix in ("ivitate", "ivitati", "ivit\u0103i", "ivit\u0103\u0163i"): word = suffix_replace(word, suffix, "iv") elif suffix in ("icitate", "icitati", "icit\u0103i", "icit\u0103\u0163i", "icator", "icatori", "iciv", "iciva", "icive", "icivi", "iciv\u0103", "ical", "icala", "icale", "icali", "ical\u0103"): word = suffix_replace(word, suffix, "ic") elif suffix in ("ativ", "ativa", "ative", "ativi", "ativ\u0103", "a\u0163iune", "atoare", "ator", "atori", "\u0103toare", "\u0103tor", "\u0103tori"): word = suffix_replace(word, suffix, "at") if suffix in r2: r2 = suffix_replace(r2, suffix, "at") elif suffix in ("itiv", "itiva", "itive", "itivi", "itiv\u0103", "i\u0163iune", "itoare", "itor", "itori"): word = suffix_replace(word, suffix, "it") if suffix in r2: r2 = suffix_replace(r2, suffix, "it") else: step1_success = False break if not replacement_done: break # STEP 2: Removal of standard suffixes for suffix in self.__step2_suffixes: if word.endswith(suffix): if suffix in r2: step2_success = True if suffix in ("iune", "iuni"): if word[-5] == "\u0163": word = "".join((word[:-5], "t")) elif suffix in ("ism", "isme", "ist", "ista", "iste", "isti", "ist\u0103", "i\u015Fti"): word = suffix_replace(word, suffix, "ist") else: word = word[:-len(suffix)] break # STEP 3: Removal of verb suffixes if not step1_success and not step2_success: for suffix in self.__step3_suffixes: if word.endswith(suffix): if suffix in rv: if suffix in ('seser\u0103\u0163i', 'seser\u0103m', 'ser\u0103\u0163i', 'sese\u015Fi', 'seser\u0103', 'ser\u0103m', 'sesem', 'se\u015Fi', 'ser\u0103', 'sese', 'a\u0163i', 'e\u0163i', 'i\u0163i', '\xE2\u0163i', 'sei', '\u0103m', 'em', 'im', '\xE2m', 'se'): word = word[:-len(suffix)] rv = rv[:-len(suffix)] else: if (not rv.startswith(suffix) and rv[rv.index(suffix)-1] not in "aeio\u0103\xE2\xEE"): word = word[:-len(suffix)] break # STEP 4: Removal of final vowel for suffix in ("ie", "a", "e", "i", "\u0103"): if word.endswith(suffix): if suffix in rv: word = word[:-len(suffix)] break word = word.replace("I", "i").replace("U", "u") return word
[docs]class RussianStemmer(_LanguageSpecificStemmer): """ The Russian Snowball stemmer. :cvar __perfective_gerund_suffixes: Suffixes to be deleted. :type __perfective_gerund_suffixes: tuple :cvar __adjectival_suffixes: Suffixes to be deleted. :type __adjectival_suffixes: tuple :cvar __reflexive_suffixes: Suffixes to be deleted. :type __reflexive_suffixes: tuple :cvar __verb_suffixes: Suffixes to be deleted. :type __verb_suffixes: tuple :cvar __noun_suffixes: Suffixes to be deleted. :type __noun_suffixes: tuple :cvar __superlative_suffixes: Suffixes to be deleted. :type __superlative_suffixes: tuple :cvar __derivational_suffixes: Suffixes to be deleted. :type __derivational_suffixes: tuple :note: A detailed description of the Russian stemming algorithm can be found under http://snowball.tartarus.org/algorithms/russian/stemmer.html """ __perfective_gerund_suffixes = ("ivshis'", "yvshis'", "vshis'", "ivshi", "yvshi", "vshi", "iv", "yv", "v") __adjectival_suffixes = ('ui^ushchi^ui^u', 'ui^ushchi^ai^a', 'ui^ushchimi', 'ui^ushchymi', 'ui^ushchego', 'ui^ushchogo', 'ui^ushchemu', 'ui^ushchomu', 'ui^ushchikh', 'ui^ushchykh', 'ui^ushchui^u', 'ui^ushchaia', 'ui^ushchoi^u', 'ui^ushchei^u', 'i^ushchi^ui^u', 'i^ushchi^ai^a', 'ui^ushchee', 'ui^ushchie', 'ui^ushchye', 'ui^ushchoe', 'ui^ushchei`', 'ui^ushchii`', 'ui^ushchyi`', 'ui^ushchoi`', 'ui^ushchem', 'ui^ushchim', 'ui^ushchym', 'ui^ushchom', 'i^ushchimi', 'i^ushchymi', 'i^ushchego', 'i^ushchogo', 'i^ushchemu', 'i^ushchomu', 'i^ushchikh', 'i^ushchykh', 'i^ushchui^u', 'i^ushchai^a', 'i^ushchoi^u', 'i^ushchei^u', 'i^ushchee', 'i^ushchie', 'i^ushchye', 'i^ushchoe', 'i^ushchei`', 'i^ushchii`', 'i^ushchyi`', 'i^ushchoi`', 'i^ushchem', 'i^ushchim', 'i^ushchym', 'i^ushchom', 'shchi^ui^u', 'shchi^ai^a', 'ivshi^ui^u', 'ivshi^ai^a', 'yvshi^ui^u', 'yvshi^ai^a', 'shchimi', 'shchymi', 'shchego', 'shchogo', 'shchemu', 'shchomu', 'shchikh', 'shchykh', 'shchui^u', 'shchai^a', 'shchoi^u', 'shchei^u', 'ivshimi', 'ivshymi', 'ivshego', 'ivshogo', 'ivshemu', 'ivshomu', 'ivshikh', 'ivshykh', 'ivshui^u', 'ivshai^a', 'ivshoi^u', 'ivshei^u', 'yvshimi', 'yvshymi', 'yvshego', 'yvshogo', 'yvshemu', 'yvshomu', 'yvshikh', 'yvshykh', 'yvshui^u', 'yvshai^a', 'yvshoi^u', 'yvshei^u', 'vshi^ui^u', 'vshi^ai^a', 'shchee', 'shchie', 'shchye', 'shchoe', 'shchei`', 'shchii`', 'shchyi`', 'shchoi`', 'shchem', 'shchim', 'shchym', 'shchom', 'ivshee', 'ivshie', 'ivshye', 'ivshoe', 'ivshei`', 'ivshii`', 'ivshyi`', 'ivshoi`', 'ivshem', 'ivshim', 'ivshym', 'ivshom', 'yvshee', 'yvshie', 'yvshye', 'yvshoe', 'yvshei`', 'yvshii`', 'yvshyi`', 'yvshoi`', 'yvshem', 'yvshim', 'yvshym', 'yvshom', 'vshimi', 'vshymi', 'vshego', 'vshogo', 'vshemu', 'vshomu', 'vshikh', 'vshykh', 'vshui^u', 'vshai^a', 'vshoi^u', 'vshei^u', 'emi^ui^u', 'emi^ai^a', 'nni^ui^u', 'nni^ai^a', 'vshee', 'vshie', 'vshye', 'vshoe', 'vshei`', 'vshii`', 'vshyi`', 'vshoi`', 'vshem', 'vshim', 'vshym', 'vshom', 'emimi', 'emymi', 'emego', 'emogo', 'ememu', 'emomu', 'emikh', 'emykh', 'emui^u', 'emai^a', 'emoi^u', 'emei^u', 'nnimi', 'nnymi', 'nnego', 'nnogo', 'nnemu', 'nnomu', 'nnikh', 'nnykh', 'nnui^u', 'nnai^a', 'nnoi^u', 'nnei^u', 'emee', 'emie', 'emye', 'emoe', 'emei`', 'emii`', 'emyi`', 'emoi`', 'emem', 'emim', 'emym', 'emom', 'nnee', 'nnie', 'nnye', 'nnoe', 'nnei`', 'nnii`', 'nnyi`', 'nnoi`', 'nnem', 'nnim', 'nnym', 'nnom', 'i^ui^u', 'i^ai^a', 'imi', 'ymi', 'ego', 'ogo', 'emu', 'omu', 'ikh', 'ykh', 'ui^u', 'ai^a', 'oi^u', 'ei^u', 'ee', 'ie', 'ye', 'oe', 'ei`', 'ii`', 'yi`', 'oi`', 'em', 'im', 'ym', 'om') __reflexive_suffixes = ("si^a", "s'") __verb_suffixes = ("esh'", 'ei`te', 'ui`te', 'ui^ut', "ish'", 'ete', 'i`te', 'i^ut', 'nno', 'ila', 'yla', 'ena', 'ite', 'ili', 'yli', 'ilo', 'ylo', 'eno', 'i^at', 'uet', 'eny', "it'", "yt'", 'ui^u', 'la', 'na', 'li', 'em', 'lo', 'no', 'et', 'ny', "t'", 'ei`', 'ui`', 'il', 'yl', 'im', 'ym', 'en', 'it', 'yt', 'i^u', 'i`', 'l', 'n') __noun_suffixes = ('ii^ami', 'ii^akh', 'i^ami', 'ii^am', 'i^akh', 'ami', 'iei`', 'i^am', 'iem', 'akh', 'ii^u', "'i^u", 'ii^a', "'i^a", 'ev', 'ov', 'ie', "'e", 'ei', 'ii', 'ei`', 'oi`', 'ii`', 'em', 'am', 'om', 'i^u', 'i^a', 'a', 'e', 'i', 'i`', 'o', 'u', 'y', "'") __superlative_suffixes = ("ei`she", "ei`sh") __derivational_suffixes = ("ost'", "ost")
[docs] def stem(self, word): """ Stem a Russian word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ if word in self.stopwords: return word chr_exceeded = False for i in range(len(word)): if ord(word[i]) > 255: chr_exceeded = True break if chr_exceeded: word = self.__cyrillic_to_roman(word) step1_success = False adjectival_removed = False verb_removed = False undouble_success = False superlative_removed = False rv, r2 = self.__regions_russian(word) # Step 1 for suffix in self.__perfective_gerund_suffixes: if rv.endswith(suffix): if suffix in ("v", "vshi", "vshis'"): if (rv[-len(suffix)-3:-len(suffix)] == "i^a" or rv[-len(suffix)-1:-len(suffix)] == "a"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] step1_success = True break else: word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] step1_success = True break if not step1_success: for suffix in self.__reflexive_suffixes: if rv.endswith(suffix): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] break for suffix in self.__adjectival_suffixes: if rv.endswith(suffix): if suffix in ('i^ushchi^ui^u', 'i^ushchi^ai^a', 'i^ushchui^u', 'i^ushchai^a', 'i^ushchoi^u', 'i^ushchei^u', 'i^ushchimi', 'i^ushchymi', 'i^ushchego', 'i^ushchogo', 'i^ushchemu', 'i^ushchomu', 'i^ushchikh', 'i^ushchykh', 'shchi^ui^u', 'shchi^ai^a', 'i^ushchee', 'i^ushchie', 'i^ushchye', 'i^ushchoe', 'i^ushchei`', 'i^ushchii`', 'i^ushchyi`', 'i^ushchoi`', 'i^ushchem', 'i^ushchim', 'i^ushchym', 'i^ushchom', 'vshi^ui^u', 'vshi^ai^a', 'shchui^u', 'shchai^a', 'shchoi^u', 'shchei^u', 'emi^ui^u', 'emi^ai^a', 'nni^ui^u', 'nni^ai^a', 'shchimi', 'shchymi', 'shchego', 'shchogo', 'shchemu', 'shchomu', 'shchikh', 'shchykh', 'vshui^u', 'vshai^a', 'vshoi^u', 'vshei^u', 'shchee', 'shchie', 'shchye', 'shchoe', 'shchei`', 'shchii`', 'shchyi`', 'shchoi`', 'shchem', 'shchim', 'shchym', 'shchom', 'vshimi', 'vshymi', 'vshego', 'vshogo', 'vshemu', 'vshomu', 'vshikh', 'vshykh', 'emui^u', 'emai^a', 'emoi^u', 'emei^u', 'nnui^u', 'nnai^a', 'nnoi^u', 'nnei^u', 'vshee', 'vshie', 'vshye', 'vshoe', 'vshei`', 'vshii`', 'vshyi`', 'vshoi`', 'vshem', 'vshim', 'vshym', 'vshom', 'emimi', 'emymi', 'emego', 'emogo', 'ememu', 'emomu', 'emikh', 'emykh', 'nnimi', 'nnymi', 'nnego', 'nnogo', 'nnemu', 'nnomu', 'nnikh', 'nnykh', 'emee', 'emie', 'emye', 'emoe', 'emei`', 'emii`', 'emyi`', 'emoi`', 'emem', 'emim', 'emym', 'emom', 'nnee', 'nnie', 'nnye', 'nnoe', 'nnei`', 'nnii`', 'nnyi`', 'nnoi`', 'nnem', 'nnim', 'nnym', 'nnom'): if (rv[-len(suffix)-3:-len(suffix)] == "i^a" or rv[-len(suffix)-1:-len(suffix)] == "a"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] adjectival_removed = True break else: word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] adjectival_removed = True break if not adjectival_removed: for suffix in self.__verb_suffixes: if rv.endswith(suffix): if suffix in ("la", "na", "ete", "i`te", "li", "i`", "l", "em", "n", "lo", "no", "et", "i^ut", "ny", "t'", "esh'", "nno"): if (rv[-len(suffix)-3:-len(suffix)] == "i^a" or rv[-len(suffix)-1:-len(suffix)] == "a"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] verb_removed = True break else: word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] verb_removed = True break if not adjectival_removed and not verb_removed: for suffix in self.__noun_suffixes: if rv.endswith(suffix): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] break # Step 2 if rv.endswith("i"): word = word[:-1] r2 = r2[:-1] # Step 3 for suffix in self.__derivational_suffixes: if r2.endswith(suffix): word = word[:-len(suffix)] break # Step 4 if word.endswith("nn"): word = word[:-1] undouble_success = True if not undouble_success: for suffix in self.__superlative_suffixes: if word.endswith(suffix): word = word[:-len(suffix)] superlative_removed = True break if word.endswith("nn"): word = word[:-1] if not undouble_success and not superlative_removed: if word.endswith("'"): word = word[:-1] if chr_exceeded: word = self.__roman_to_cyrillic(word) return word
def __regions_russian(self, word): """ Return the regions RV and R2 which are used by the Russian stemmer. In any word, RV is the region after the first vowel, or the end of the word if it contains no vowel. R2 is the region after the first non-vowel following a vowel in R1, or the end of the word if there is no such non-vowel. R1 is the region after the first non-vowel following a vowel, or the end of the word if there is no such non-vowel. :param word: The Russian word whose regions RV and R2 are determined. :type word: str or unicode :return: the regions RV and R2 for the respective Russian word. :rtype: tuple :note: This helper method is invoked by the stem method of the subclass RussianStemmer. It is not to be invoked directly! """ r1 = "" r2 = "" rv = "" vowels = ("A", "U", "E", "a", "e", "i", "o", "u", "y") word = (word.replace("i^a", "A") .replace("i^u", "U") .replace("e`", "E")) for i in range(1, len(word)): if word[i] not in vowels and word[i-1] in vowels: r1 = word[i+1:] break for i in range(1, len(r1)): if r1[i] not in vowels and r1[i-1] in vowels: r2 = r1[i+1:] break for i in range(len(word)): if word[i] in vowels: rv = word[i+1:] break r2 = (r2.replace("A", "i^a") .replace("U", "i^u") .replace("E", "e`")) rv = (rv.replace("A", "i^a") .replace("U", "i^u") .replace("E", "e`")) return (rv, r2) def __cyrillic_to_roman(self, word): """ Transliterate a Russian word into the Roman alphabet. A Russian word whose letters consist of the Cyrillic alphabet are transliterated into the Roman alphabet in order to ease the forthcoming stemming process. :param word: The word that is transliterated. :type word: unicode :return: the transliterated word. :rtype: unicode :note: This helper method is invoked by the stem method of the subclass RussianStemmer. It is not to be invoked directly! """ word = (word.replace("\u0410", "a").replace("\u0430", "a") .replace("\u0411", "b").replace("\u0431", "b") .replace("\u0412", "v").replace("\u0432", "v") .replace("\u0413", "g").replace("\u0433", "g") .replace("\u0414", "d").replace("\u0434", "d") .replace("\u0415", "e").replace("\u0435", "e") .replace("\u0401", "e").replace("\u0451", "e") .replace("\u0416", "zh").replace("\u0436", "zh") .replace("\u0417", "z").replace("\u0437", "z") .replace("\u0418", "i").replace("\u0438", "i") .replace("\u0419", "i`").replace("\u0439", "i`") .replace("\u041A", "k").replace("\u043A", "k") .replace("\u041B", "l").replace("\u043B", "l") .replace("\u041C", "m").replace("\u043C", "m") .replace("\u041D", "n").replace("\u043D", "n") .replace("\u041E", "o").replace("\u043E", "o") .replace("\u041F", "p").replace("\u043F", "p") .replace("\u0420", "r").replace("\u0440", "r") .replace("\u0421", "s").replace("\u0441", "s") .replace("\u0422", "t").replace("\u0442", "t") .replace("\u0423", "u").replace("\u0443", "u") .replace("\u0424", "f").replace("\u0444", "f") .replace("\u0425", "kh").replace("\u0445", "kh") .replace("\u0426", "t^s").replace("\u0446", "t^s") .replace("\u0427", "ch").replace("\u0447", "ch") .replace("\u0428", "sh").replace("\u0448", "sh") .replace("\u0429", "shch").replace("\u0449", "shch") .replace("\u042A", "''").replace("\u044A", "''") .replace("\u042B", "y").replace("\u044B", "y") .replace("\u042C", "'").replace("\u044C", "'") .replace("\u042D", "e`").replace("\u044D", "e`") .replace("\u042E", "i^u").replace("\u044E", "i^u") .replace("\u042F", "i^a").replace("\u044F", "i^a")) return word def __roman_to_cyrillic(self, word): """ Transliterate a Russian word back into the Cyrillic alphabet. A Russian word formerly transliterated into the Roman alphabet in order to ease the stemming process, is transliterated back into the Cyrillic alphabet, its original form. :param word: The word that is transliterated. :type word: str or unicode :return: word, the transliterated word. :rtype: unicode :note: This helper method is invoked by the stem method of the subclass RussianStemmer. It is not to be invoked directly! """ word = (word.replace("i^u", "\u044E").replace("i^a", "\u044F") .replace("shch", "\u0449").replace("kh", "\u0445") .replace("t^s", "\u0446").replace("ch", "\u0447") .replace("e`", "\u044D").replace("i`", "\u0439") .replace("sh", "\u0448").replace("k", "\u043A") .replace("e", "\u0435").replace("zh", "\u0436") .replace("a", "\u0430").replace("b", "\u0431") .replace("v", "\u0432").replace("g", "\u0433") .replace("d", "\u0434").replace("e", "\u0435") .replace("z", "\u0437").replace("i", "\u0438") .replace("l", "\u043B").replace("m", "\u043C") .replace("n", "\u043D").replace("o", "\u043E") .replace("p", "\u043F").replace("r", "\u0440") .replace("s", "\u0441").replace("t", "\u0442") .replace("u", "\u0443").replace("f", "\u0444") .replace("''", "\u044A").replace("y", "\u044B") .replace("'", "\u044C")) return word
[docs]class SpanishStemmer(_StandardStemmer): """ The Spanish Snowball stemmer. :cvar __vowels: The Spanish vowels. :type __vowels: unicode :cvar __step0_suffixes: Suffixes to be deleted in step 0 of the algorithm. :type __step0_suffixes: tuple :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2a_suffixes: Suffixes to be deleted in step 2a of the algorithm. :type __step2a_suffixes: tuple :cvar __step2b_suffixes: Suffixes to be deleted in step 2b of the algorithm. :type __step2b_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :note: A detailed description of the Spanish stemming algorithm can be found under http://snowball.tartarus.org/algorithms/spanish/stemmer.html """ __vowels = "aeiou\xE1\xE9\xED\xF3\xFA\xFC" __step0_suffixes = ("selas", "selos", "sela", "selo", "las", "les", "los", "nos", "me", "se", "la", "le", "lo") __step1_suffixes = ('amientos', 'imientos', 'amiento', 'imiento', 'aciones', 'uciones', 'adoras', 'adores', 'ancias', 'log\xEDas', 'encias', 'amente', 'idades', 'anzas', 'ismos', 'ables', 'ibles', 'istas', 'adora', 'aci\xF3n', 'antes', 'ancia', 'log\xEDa', 'uci\xf3n', 'encia', 'mente', 'anza', 'icos', 'icas', 'ismo', 'able', 'ible', 'ista', 'osos', 'osas', 'ador', 'ante', 'idad', 'ivas', 'ivos', 'ico', 'ica', 'oso', 'osa', 'iva', 'ivo') __step2a_suffixes = ('yeron', 'yendo', 'yamos', 'yais', 'yan', 'yen', 'yas', 'yes', 'ya', 'ye', 'yo', 'y\xF3') __step2b_suffixes = ('ar\xEDamos', 'er\xEDamos', 'ir\xEDamos', 'i\xE9ramos', 'i\xE9semos', 'ar\xEDais', 'aremos', 'er\xEDais', 'eremos', 'ir\xEDais', 'iremos', 'ierais', 'ieseis', 'asteis', 'isteis', '\xE1bamos', '\xE1ramos', '\xE1semos', 'ar\xEDan', 'ar\xEDas', 'ar\xE9is', 'er\xEDan', 'er\xEDas', 'er\xE9is', 'ir\xEDan', 'ir\xEDas', 'ir\xE9is', 'ieran', 'iesen', 'ieron', 'iendo', 'ieras', 'ieses', 'abais', 'arais', 'aseis', '\xE9amos', 'ar\xE1n', 'ar\xE1s', 'ar\xEDa', 'er\xE1n', 'er\xE1s', 'er\xEDa', 'ir\xE1n', 'ir\xE1s', 'ir\xEDa', 'iera', 'iese', 'aste', 'iste', 'aban', 'aran', 'asen', 'aron', 'ando', 'abas', 'adas', 'idas', 'aras', 'ases', '\xEDais', 'ados', 'idos', 'amos', 'imos', 'emos', 'ar\xE1', 'ar\xE9', 'er\xE1', 'er\xE9', 'ir\xE1', 'ir\xE9', 'aba', 'ada', 'ida', 'ara', 'ase', '\xEDan', 'ado', 'ido', '\xEDas', '\xE1is', '\xE9is', '\xEDa', 'ad', 'ed', 'id', 'an', 'i\xF3', 'ar', 'er', 'ir', 'as', '\xEDs', 'en', 'es') __step3_suffixes = ("os", "a", "e", "o", "\xE1", "\xE9", "\xED", "\xF3")
[docs] def stem(self, word): """ Stem a Spanish word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word step1_success = False r1, r2 = self._r1r2_standard(word, self.__vowels) rv = self._rv_standard(word, self.__vowels) # STEP 0: Attached pronoun for suffix in self.__step0_suffixes: if not (word.endswith(suffix) and rv.endswith(suffix)): continue if ((rv[:-len(suffix)].endswith(("ando", "\xE1ndo", "ar", "\xE1r", "er", "\xE9r", "iendo", "i\xE9ndo", "ir", "\xEDr"))) or (rv[:-len(suffix)].endswith("yendo") and word[:-len(suffix)].endswith("uyendo"))): word = self.__replace_accented(word[:-len(suffix)]) r1 = self.__replace_accented(r1[:-len(suffix)]) r2 = self.__replace_accented(r2[:-len(suffix)]) rv = self.__replace_accented(rv[:-len(suffix)]) break # STEP 1: Standard suffix removal for suffix in self.__step1_suffixes: if not word.endswith(suffix): continue if suffix == "amente" and r1.endswith(suffix): step1_success = True word = word[:-6] r2 = r2[:-6] rv = rv[:-6] if r2.endswith("iv"): word = word[:-2] r2 = r2[:-2] rv = rv[:-2] if r2.endswith("at"): word = word[:-2] rv = rv[:-2] elif r2.endswith(("os", "ic", "ad")): word = word[:-2] rv = rv[:-2] elif r2.endswith(suffix): step1_success = True if suffix in ("adora", "ador", "aci\xF3n", "adoras", "adores", "aciones", "ante", "antes", "ancia", "ancias"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] if r2.endswith("ic"): word = word[:-2] rv = rv[:-2] elif suffix in ("log\xEDa", "log\xEDas"): word = suffix_replace(word, suffix, "log") rv = suffix_replace(rv, suffix, "log") elif suffix in ("uci\xF3n", "uciones"): word = suffix_replace(word, suffix, "u") rv = suffix_replace(rv, suffix, "u") elif suffix in ("encia", "encias"): word = suffix_replace(word, suffix, "ente") rv = suffix_replace(rv, suffix, "ente") elif suffix == "mente": word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] if r2.endswith(("ante", "able", "ible")): word = word[:-4] rv = rv[:-4] elif suffix in ("idad", "idades"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] for pre_suff in ("abil", "ic", "iv"): if r2.endswith(pre_suff): word = word[:-len(pre_suff)] rv = rv[:-len(pre_suff)] elif suffix in ("ivo", "iva", "ivos", "ivas"): word = word[:-len(suffix)] r2 = r2[:-len(suffix)] rv = rv[:-len(suffix)] if r2.endswith("at"): word = word[:-2] rv = rv[:-2] else: word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 2a: Verb suffixes beginning 'y' if not step1_success: for suffix in self.__step2a_suffixes: if (rv.endswith(suffix) and word[-len(suffix)-1:-len(suffix)] == "u"): word = word[:-len(suffix)] rv = rv[:-len(suffix)] break # STEP 2b: Other verb suffixes for suffix in self.__step2b_suffixes: if rv.endswith(suffix): word = word[:-len(suffix)] rv = rv[:-len(suffix)] if suffix in ("en", "es", "\xE9is", "emos"): if word.endswith("gu"): word = word[:-1] if rv.endswith("gu"): rv = rv[:-1] break # STEP 3: Residual suffix for suffix in self.__step3_suffixes: if rv.endswith(suffix): word = word[:-len(suffix)] if suffix in ("e", "\xE9"): rv = rv[:-len(suffix)] if word[-2:] == "gu" and rv.endswith("u"): word = word[:-1] break word = self.__replace_accented(word) return word
def __replace_accented(self, word): """ Replaces all accented letters on a word with their non-accented counterparts. :param word: A spanish word, with or without accents :type word: str or unicode :return: a word with the accented letters (á, é, í, ó, ú) replaced with their non-accented counterparts (a, e, i, o, u) :rtype: str or unicode """ return (word.replace("\xE1", "a") .replace("\xE9", "e") .replace("\xED", "i") .replace("\xF3", "o") .replace("\xFA", "u"))
[docs]class SwedishStemmer(_ScandinavianStemmer): """ The Swedish Snowball stemmer. :cvar __vowels: The Swedish vowels. :type __vowels: unicode :cvar __s_ending: Letters that may directly appear before a word final 's'. :type __s_ending: unicode :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm. :type __step1_suffixes: tuple :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm. :type __step2_suffixes: tuple :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm. :type __step3_suffixes: tuple :note: A detailed description of the Swedish stemming algorithm can be found under http://snowball.tartarus.org/algorithms/swedish/stemmer.html """ __vowels = "aeiouy\xE4\xE5\xF6" __s_ending = "bcdfghjklmnoprtvy" __step1_suffixes = ("heterna", "hetens", "heter", "heten", "anden", "arnas", "ernas", "ornas", "andes", "andet", "arens", "arna", "erna", "orna", "ande", "arne", "aste", "aren", "ades", "erns", "ade", "are", "ern", "ens", "het", "ast", "ad", "en", "ar", "er", "or", "as", "es", "at", "a", "e", "s") __step2_suffixes = ("dd", "gd", "nn", "dt", "gt", "kt", "tt") __step3_suffixes = ("fullt", "l\xF6st", "els", "lig", "ig")
[docs] def stem(self, word): """ Stem a Swedish word and return the stemmed form. :param word: The word that is stemmed. :type word: str or unicode :return: The stemmed form. :rtype: unicode """ word = word.lower() if word in self.stopwords: return word r1 = self._r1_scandinavian(word, self.__vowels) # STEP 1 for suffix in self.__step1_suffixes: if r1.endswith(suffix): if suffix == "s": if word[-2] in self.__s_ending: word = word[:-1] r1 = r1[:-1] else: word = word[:-len(suffix)] r1 = r1[:-len(suffix)] break # STEP 2 for suffix in self.__step2_suffixes: if r1.endswith(suffix): word = word[:-1] r1 = r1[:-1] break # STEP 3 for suffix in self.__step3_suffixes: if r1.endswith(suffix): if suffix in ("els", "lig", "ig"): word = word[:-len(suffix)] elif suffix in ("fullt", "l\xF6st"): word = word[:-1] break return word
[docs]def demo(): """ This function provides a demonstration of the Snowball stemmers. After invoking this function and specifying a language, it stems an excerpt of the Universal Declaration of Human Rights (which is a part of the NLTK corpus collection) and then prints out the original and the stemmed text. """ import re from nltk.corpus import udhr udhr_corpus = {"danish": "Danish_Dansk-Latin1", "dutch": "Dutch_Nederlands-Latin1", "english": "English-Latin1", "finnish": "Finnish_Suomi-Latin1", "french": "French_Francais-Latin1", "german": "German_Deutsch-Latin1", "hungarian": "Hungarian_Magyar-UTF8", "italian": "Italian_Italiano-Latin1", "norwegian": "Norwegian-Latin1", "porter": "English-Latin1", "portuguese": "Portuguese_Portugues-Latin1", "romanian": "Romanian_Romana-Latin2", "russian": "Russian-UTF8", "spanish": "Spanish-Latin1", "swedish": "Swedish_Svenska-Latin1", } print("\n") print("******************************") print("Demo for the Snowball stemmers") print("******************************") while True: language = compat.raw_input("Please enter the name of the language " + "to be demonstrated\n" + "/".join(SnowballStemmer.languages) + "\n" + "(enter 'exit' in order to leave): ") if language == "exit": break if language not in SnowballStemmer.languages: print(("\nOops, there is no stemmer for this language. " + "Please try again.\n")) continue stemmer = SnowballStemmer(language) excerpt = udhr.words(udhr_corpus[language]) [:300] stemmed = " ".join(stemmer.stem(word) for word in excerpt) stemmed = re.sub(r"(.{,70})\s", r'\1\n', stemmed+' ').rstrip() excerpt = " ".join(excerpt) excerpt = re.sub(r"(.{,70})\s", r'\1\n', excerpt+' ').rstrip() print("\n") print('-' * 70) print('ORIGINAL'.center(70)) print(excerpt) print("\n\n") print('STEMMED RESULTS'.center(70)) print(stemmed) print('-' * 70) print("\n")