edu.txstate.dmlab.clusteringwiki.cluster.HierarchicalFrequentPhraseClusterer.java Source code

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Here is the source code for edu.txstate.dmlab.clusteringwiki.cluster.HierarchicalFrequentPhraseClusterer.java

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package edu.txstate.dmlab.clusteringwiki.cluster;

/**
 *  ClusteringWiki - personalized and collaborative clustering of search results
 *  Copyright (C) 2010  Texas State University-San Marcos
 *  
 *  Contact: http://dmlab.cs.txstate.edu
 * 
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 * 
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 * 
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.List;
import java.util.Map;

import org.apache.commons.lang.StringUtils;

import edu.txstate.dmlab.clusteringwiki.app.ApplicationSettings;
import edu.txstate.dmlab.clusteringwiki.preprocess.ICollectionContext;

/**
 * Hierarchical implementation of the frequent phrase clustering algorithm
 * 
 * @author David C. Anastasiu
 *
 */
public class HierarchicalFrequentPhraseClusterer extends FrequentPhraseClusterer implements IClusterer {

    /**
     * Controller
     * @param theContext
     */
    public HierarchicalFrequentPhraseClusterer(ICollectionContext theContext) {
        super(theContext);
    }

    /**
     * Whether a cluster should be split up into multiple cluster children
     * @param c
     * @return
     */
    protected boolean shouldSubCluster(ICluster c) {
        final int level = c.getLevel();
        final int[] terms = ((FrequentPhraseCluster) c).getLabelTerms();
        final int ln = terms != null ? terms.length : 0;
        //don't keep clustering the Other cluster
        if (StringUtils.equals(FrequentPhraseCluster.OTHER_LABEL, c.getLabel()))
            return false;
        //sub-cluster if root or cluster has more than 10 docs and level is
        //below max clustering level
        return level == 0 || (c.size() > 5 && level < MAX_CLUSTERING_LEVELS
                && ln >= ApplicationSettings.MINIMUM_FREQUENT_PHRASE_LENGTH);
    }

    /**
     * perform hierarchical clustering
     * @param c
     * @return
     */
    protected ICluster subCluster(ICluster c) {
        List<ICluster> children = c.getChildren();
        if (children == null && shouldSubCluster(c)) {
            int[] docs;
            if (c.getLevel() == 0) {
                List<IClusterDocument> clusterDocs = c.getAllDocs();
                docs = new int[clusterDocs.size()];
                int i = 0;
                for (IClusterDocument doc : clusterDocs)
                    docs[i++] = doc.getIndex();
            } else {
                Map<Integer, IClusterDocument> docsMap = c.getDocs();
                docs = new int[docsMap.size()];
                int i = 0;
                for (Integer index : docsMap.keySet())
                    docs[i++] = index;
            }

            //only continue subclustering if there are at least 2 child 
            //clusters produced
            final List<ICluster> possibleChildren = levelCluster(c, docs);
            if (possibleChildren != null && (c.getLevel() == 0 || possibleChildren.size() > 1)) {
                children = possibleChildren;
            }
            c.setChildren(children);
        }
        if (children != null) {
            for (ICluster child : children) {
                if (shouldSubCluster(child)) {
                    ICluster possibleChild = subCluster(child);
                    //only continue subclustering if there are at least 2 child 
                    //clusters produced
                    final List<ICluster> possibleChildren = possibleChild.getChildren();
                    if (possibleChildren != null && possibleChildren.size() > 1)
                        child = possibleChild;
                }
            }
        }
        return c;
    }

    /**
     * Cluster a set of documentsToCluster provided as an array of indexes within the
     * term document matrix.  Provides a root cluster with an attached
     * hierarchy (tree) of children clusters
     * @param docs
     * @return
     */
    @Override
    public ICluster cluster(int[] docs) {
        ICluster root = new FrequentPhraseCluster(getNextClusterId(), context);
        root.setLevel(0);
        root.deduceLabel();
        return subCluster(root);
    }
}