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.util.Iterator;
033
034import org.openimaj.util.pair.DoubleObjectPair;
035
036import ch.akuhn.matrix.Vector;
037import ch.akuhn.matrix.eigenvalues.Eigenvalues;
038
039/**
040 * A forward or backward iterator of eigen vector/value pairs
041 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
042 *
043 */
044public final class FBEigenIterator implements
045                Iterator<DoubleObjectPair<Vector>> {
046
047        private int pos;
048        private int dir;
049        private double[] values;
050        private Vector[] vectors;
051        private int lim;
052        /**
053         * @param evd
054         */
055        public FBEigenIterator(Eigenvalues evd) {
056                this.values = evd.value;
057                this.vectors = evd.vector;
058                this.pos = values.length-1;
059                this.dir = -1;
060                this.lim = -1;
061        }
062
063        @Override
064        public void remove() { throw new UnsupportedOperationException();}
065
066        @Override
067        public DoubleObjectPair<Vector> next() {
068                DoubleObjectPair<Vector> ret = new DoubleObjectPair<Vector>(this.values[pos], this.vectors[pos]);
069                pos += dir;
070                return ret;
071        }
072
073        @Override
074        public boolean hasNext() {
075                return pos != lim;
076        }
077}