/*
* Copyright 2008-2011 Grant Ingersoll, Thomas Morton and Drew Farris
*
* 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.
* -------------------
* To purchase or learn more about Taming Text, by Grant Ingersoll, Thomas Morton and Drew Farris, visit
* http://www.manning.com/ingersoll
*/
package com.tamingtext.classifier.bayes;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.mahout.classifier.ClassifierResult;
import org.apache.mahout.classifier.bayes.ClassifierContext;
import org.apache.mahout.classifier.bayes.InvalidDatastoreException;
import org.apache.solr.common.SolrInputDocument;
import org.apache.solr.common.SolrInputField;
import org.apache.solr.update.AddUpdateCommand;
import org.apache.solr.update.processor.UpdateRequestProcessor;
/** A Solr <code>UpdateRequestProcessor</code> that uses the Mahout Bayes
* Classifier to add a category label to documents at index time.
* <p/>
* @see com.tamingtext.classifier.bayes.BayesUpdateRequestProcessorFactory
*
*/
public class BayesUpdateRequestProcessor extends UpdateRequestProcessor {
public static final String NO_LABEL = "nullDefault";
ClassifierContext ctx;
String inputField;
String outputField;
String defaultCategory;
Analyzer analyzer;
public BayesUpdateRequestProcessor(ClassifierContext ctx, Analyzer analyzer,
String inputField, String outputField, String defaultCategory, UpdateRequestProcessor next) {
super(next);
this.ctx = ctx;
this.analyzer = analyzer;
this.inputField = inputField;
this.outputField = outputField;
this.defaultCategory = defaultCategory;
if (this.defaultCategory == null) {
this.defaultCategory = NO_LABEL;
}
}
@Override
public void processAdd(AddUpdateCommand cmd) throws IOException {
SolrInputDocument doc = cmd.getSolrInputDocument();
classifyDocument(doc);
super.processAdd(cmd);
}
public void classifyDocument(SolrInputDocument doc) throws IOException {
try {
//<start id="mahout.bayes.classify"/>
SolrInputField field = doc.getField(inputField);
String[] tokens = tokenizeField(inputField, field);
ClassifierResult result = ctx.classifyDocument(tokens,
defaultCategory);
if (result != null && result.getLabel() != NO_LABEL) {
doc.addField(outputField, result.getLabel());
}
//<end id="mahout.bayes.classify"/>
}
catch (InvalidDatastoreException e) {
throw new IOException("Invalid Classifier Datastore", e);
}
}
public String[] tokenizeField(String fieldName, SolrInputField field) throws IOException {
if (field == null) return new String[0];
if (!(field.getValue() instanceof String)) return new String[0];
//<start id="mahout.bayes.tokenize"/>
String input = (String) field.getValue();
ArrayList<String> tokenList = new ArrayList<String>();
TokenStream ts = analyzer.tokenStream(inputField,
new StringReader(input));
while (ts.incrementToken()) {
tokenList.add(ts.getAttribute(CharTermAttribute.class).toString());
}
String[] tokens = tokenList.toArray(new String[tokenList.size()]);
//<end id="mahout.bayes.tokenize"/>
return tokens;
}
}