001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.ml.clustering.spectral;
031
032import java.io.File;
033import java.io.IOException;
034
035import org.apache.logging.log4j.Logger;
036import org.apache.logging.log4j.LogManager;
037
038import org.openimaj.io.IOUtils;
039
040import ch.akuhn.matrix.SparseMatrix;
041import ch.akuhn.matrix.eigenvalues.Eigenvalues;
042
043/**
044 * {@link DoubleSpectralClustering} extention which knows how to write and read its eigenvectors to disk
045 * and therefore not regenerate them when calling the underlying {@link PreparedSpectralClustering} 
046 * 
047 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
048 *
049 */
050public class CachedDoubleSpectralClustering extends DoubleSpectralClustering{
051        private final static Logger logger = LogManager.getLogger(CachedDoubleSpectralClustering.class);
052        private File cache;
053
054        /**
055         * @param cache location to cache the eigenvectors
056         * @param conf
057         * cluster the eigen vectors
058         */
059        public CachedDoubleSpectralClustering(File cache, SpectralClusteringConf<double[]> conf) {
060                super(conf);
061                this.cache = cache;
062        }
063        
064        @Override
065        protected Eigenvalues spectralCluster(SparseMatrix data) {
066                Eigenvalues eig = null;
067                if(cache.exists()){
068                        logger.debug("Loading eigenvectors from cache");
069                        try {
070                                eig = IOUtils.readFromFile(cache);
071                        } catch (IOException e) {
072                                throw new RuntimeException(e);
073                        }
074                }
075                else{                   
076                        // Compute the laplacian of the graph
077                        logger.debug("Cache empty, recreating eigenvectors");
078                        final SparseMatrix laplacian = laplacian(data);
079                        eig = laplacianEigenVectors(laplacian);
080                        try {
081                                logger.debug("Writing eigenvectors to cache");
082                                IOUtils.writeToFile(eig, cache);
083                        } catch (IOException e) {
084                                throw new RuntimeException(e);
085                        }
086                }
087                
088                return eig;
089        }
090        
091}