com.tamingtext.classifier.bayes.BayesUpdateRequestProcessor.java Source code

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Here is the source code for com.tamingtext.classifier.bayes.BayesUpdateRequestProcessor.java

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/*
 * 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;
    }
}