Source code for nltk.test.unit.test_stem

import unittest
from contextlib import closing

from nltk import data
from nltk.stem.porter import PorterStemmer
from nltk.stem.snowball import SnowballStemmer

[docs]class SnowballTest(unittest.TestCase):
[docs] def test_arabic(self): """ this unit testing for test the snowball arabic light stemmer this stemmer deals with prefixes and suffixes """ # Test where the ignore_stopwords=True. ar_stemmer = SnowballStemmer("arabic", True) assert ar_stemmer.stem("الْعَرَبِــــــيَّة") == "عرب" assert ar_stemmer.stem("العربية") == "عرب" assert ar_stemmer.stem("فقالوا") == "قال" assert ar_stemmer.stem("الطالبات") == "طالب" assert ar_stemmer.stem("فالطالبات") == "طالب" assert ar_stemmer.stem("والطالبات") == "طالب" assert ar_stemmer.stem("الطالبون") == "طالب" assert ar_stemmer.stem("اللذان") == "اللذان" assert ar_stemmer.stem("من") == "من" # Test where the ignore_stopwords=False. ar_stemmer = SnowballStemmer("arabic", False) assert ar_stemmer.stem("اللذان") == "اللذ" # this is a stop word assert ar_stemmer.stem("الطالبات") == "طالب" assert ar_stemmer.stem("الكلمات") == "كلم" # test where create the arabic stemmer without given init value to ignore_stopwords ar_stemmer = SnowballStemmer("arabic") assert ar_stemmer.stem("الْعَرَبِــــــيَّة") == "عرب" assert ar_stemmer.stem("العربية") == "عرب" assert ar_stemmer.stem("فقالوا") == "قال" assert ar_stemmer.stem("الطالبات") == "طالب" assert ar_stemmer.stem("الكلمات") == "كلم"
[docs] def test_russian(self): stemmer_russian = SnowballStemmer("russian") assert stemmer_russian.stem("авантненькая") == "авантненьк"
[docs] def test_german(self): stemmer_german = SnowballStemmer("german") stemmer_german2 = SnowballStemmer("german", ignore_stopwords=True) assert stemmer_german.stem("Schr\xe4nke") == "schrank" assert stemmer_german2.stem("Schr\xe4nke") == "schrank" assert stemmer_german.stem("keinen") == "kein" assert stemmer_german2.stem("keinen") == "keinen"
[docs] def test_spanish(self): stemmer = SnowballStemmer("spanish") assert stemmer.stem("Visionado") == "vision" # The word 'algue' was raising an IndexError assert stemmer.stem("algue") == "algu"
[docs] def test_short_strings_bug(self): stemmer = SnowballStemmer("english") assert stemmer.stem("y's") == "y"
[docs]class PorterTest(unittest.TestCase): def _vocabulary(self): with closing( data.find("stemmers/porter_test/porter_vocabulary.txt").open( encoding="utf-8" ) ) as fp: return def _test_against_expected_output(self, stemmer_mode, expected_stems): stemmer = PorterStemmer(mode=stemmer_mode) for word, true_stem in zip(self._vocabulary(), expected_stems): our_stem = stemmer.stem(word) assert ( our_stem == true_stem ), "{} should stem to {} in {} mode but got {}".format( word, true_stem, stemmer_mode, our_stem, )
[docs] def test_vocabulary_martin_mode(self): """Tests all words from the test vocabulary provided by M Porter The sample vocabulary and output were sourced from and and are linked to from the Porter Stemmer algorithm's homepage at """ with closing( data.find("stemmers/porter_test/porter_martin_output.txt").open( encoding="utf-8" ) ) as fp: self._test_against_expected_output( PorterStemmer.MARTIN_EXTENSIONS, )
[docs] def test_vocabulary_nltk_mode(self): with closing( data.find("stemmers/porter_test/porter_nltk_output.txt").open( encoding="utf-8" ) ) as fp: self._test_against_expected_output( PorterStemmer.NLTK_EXTENSIONS, )
[docs] def test_vocabulary_original_mode(self): # The list of stems for this test was generated by taking the # Martin-blessed stemmer from # # and removing all the --DEPARTURE-- sections from it and # running it against Martin's test vocabulary. with closing( data.find("stemmers/porter_test/porter_original_output.txt").open( encoding="utf-8" ) ) as fp: self._test_against_expected_output( PorterStemmer.ORIGINAL_ALGORITHM, ) self._test_against_expected_output( PorterStemmer.ORIGINAL_ALGORITHM, data.find("stemmers/porter_test/porter_original_output.txt") .open(encoding="utf-8") .read() .splitlines(), )
[docs] def test_oed_bug(self): """Test for bug Ensures that 'oed' can be stemmed without throwing an error. """ assert PorterStemmer().stem("oed") == "o"
[docs] def test_lowercase_option(self): """Test for improvement on Ensures that stems are lowercased when `to_lowercase=True` """ porter = PorterStemmer() assert porter.stem("On") == "on" assert porter.stem("I") == "i" assert porter.stem("I", to_lowercase=False) == "I" assert porter.stem("Github") == "github" assert porter.stem("Github", to_lowercase=False) == "Github"