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_base.py
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_base.py
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#
# Pyserini: Python interface to the Anserini IR toolkit built on Lucene
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from typing import List
from ..pyclass import autoclass, JString
# Wrappers around Lucene classes
JAnalyzer = autoclass('org.apache.lucene.analysis.Analyzer')
JArabicAnalyzer = autoclass('org.apache.lucene.analysis.ar.ArabicAnalyzer')
JBengaliAnalyzer = autoclass('org.apache.lucene.analysis.bn.BengaliAnalyzer')
JCJKAnalyzer = autoclass('org.apache.lucene.analysis.cjk.CJKAnalyzer')
JGermanAnalyzer = autoclass('org.apache.lucene.analysis.de.GermanAnalyzer')
JSpanishAnalyzer = autoclass('org.apache.lucene.analysis.es.SpanishAnalyzer')
JFrenchAnalyzer = autoclass('org.apache.lucene.analysis.fr.FrenchAnalyzer')
JHindiAnalyzer = autoclass('org.apache.lucene.analysis.hi.HindiAnalyzer')
JDefaultEnglishAnalyzer = autoclass('io.anserini.analysis.DefaultEnglishAnalyzer')
JCharArraySet = autoclass('org.apache.lucene.analysis.CharArraySet')
# Wrappers around Anserini classes
JAnalyzerUtils = autoclass('io.anserini.analysis.AnalyzerUtils')
JFreebaseAnalyzer = autoclass('io.anserini.analysis.FreebaseAnalyzer')
JTweetAnalyzer = autoclass('io.anserini.analysis.TweetAnalyzer')
def get_lucene_analyzer(name='english', stemming=True, stemmer='porter', stopwords=True) -> JAnalyzer:
"""Create a Lucene ``Analyzer`` with specific settings.
Parameters
----------
name : str
Name of analyzer.
stemming : bool
Set to stem.
stemmer : str
Stemmer to use.
stopwords : bool
Set to filter stopwords.
Returns
-------
JAnalyzer
Java ``Analyzer`` with specified settings.
"""
if name.lower() == 'arabic':
return JArabicAnalyzer()
elif name.lower() == 'bengali':
return JBengaliAnalyzer()
elif name.lower() == 'cjk':
return JCJKAnalyzer()
elif name.lower() == 'german':
return JGermanAnalyzer()
elif name.lower() == 'spanish':
return JSpanishAnalyzer()
elif name.lower() == 'french':
return JFrenchAnalyzer()
elif name.lower() == 'hindi':
return JHindiAnalyzer()
elif name.lower() == 'freebase':
return JFreebaseAnalyzer()
elif name.lower() == 'tweet':
return JTweetAnalyzer()
elif name.lower() == 'english':
if stemming:
if stopwords:
return JDefaultEnglishAnalyzer.newStemmingInstance(JString(stemmer))
else:
return JDefaultEnglishAnalyzer.newStemmingInstance(JString(stemmer), JCharArraySet.EMPTY_SET)
else:
if stopwords:
return JDefaultEnglishAnalyzer.newNonStemmingInstance()
else:
return JDefaultEnglishAnalyzer.newNonStemmingInstance(JCharArraySet.EMPTY_SET)
else:
raise ValueError('Invalid configuration.')
class Analyzer:
"""Python wrapper around a Lucene ``Analyzer`` to simplify analysis.
Parameters
----------
analyzer : JAnalyzer
Lucene ``Analyzer``.
"""
def __init__(self, analyzer):
if not isinstance(analyzer, JAnalyzer):
raise TypeError('Invalid JAnalyzer!')
self.analyzer = analyzer
def analyze(self, text: str) -> List[str]:
"""Analyze a piece of text.
Parameters
----------
text : str
Text to analyze.
Returns
-------
List[str]
List of tokens corresponding to the output of the analyzer.
"""
results = JAnalyzerUtils.analyze(self.analyzer, JString(text.encode('utf-8')))
tokens = []
for token in results.toArray():
tokens.append(token)
return tokens