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.demos.sandbox.ml.linear.learner.stream;
031
032import gov.sandia.cognition.math.matrix.Vector;
033
034import java.util.Comparator;
035import java.util.Iterator;
036
037import org.openimaj.ml.linear.learner.BilinearSparseOnlineLearner;
038import org.openimaj.ml.linear.learner.IncrementalBilinearSparseOnlineLearner;
039import org.openimaj.util.queue.BoundedPriorityQueue;
040
041import com.google.common.collect.BiMap;
042
043/**
044 * Iterate over words in terms of their importance
045 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
046 *
047 */
048public class SortedImportantWords implements Iterable<String>{
049        BiMap<String,Integer> words;
050        int[] indexes;
051        private int taskIndex;
052        private Vector wordWeights;
053
054
055        /**
056         * @param task The task for which word importance is to be measured
057         * @param learner The incremental learner (giving access to the words)
058         * @param bilearner The source of the word parameters
059         * @param size The number of words
060         */
061        public SortedImportantWords(
062                        String task,
063                        IncrementalBilinearSparseOnlineLearner learner,
064                        BilinearSparseOnlineLearner bilearner,
065                        int size
066        ) {
067                this.words = learner.getVocabulary();
068                this.taskIndex = learner.getDependantValues().get(task);
069                this.wordWeights = bilearner.getW().getColumn(taskIndex);
070                BoundedPriorityQueue<Integer> queue = new BoundedPriorityQueue<Integer>(size, new Comparator<Integer>() {
071
072                        @Override
073                        public int compare(Integer o1, Integer o2) {
074                                Double weighto1 = wordWeights.getElement(o1);
075                                Double weighto2 = wordWeights.getElement(o2);
076                                return -weighto1.compareTo(weighto2);
077                        }
078                });
079                for (int i = 0; i < wordWeights.getDimensionality(); i++) {
080                        queue.add(i);
081                }
082                this.indexes = new int[size];
083                int i = 0;
084                while(!queue.isEmpty()){
085                        this.indexes[i++] = queue.pollTail();
086                }
087        }
088
089
090        @Override
091        public Iterator<String> iterator() {
092                return new Iterator<String>() {
093                        int index = 0;
094                        @Override
095                        public void remove() {
096                                throw new UnsupportedOperationException();
097                        }
098
099                        @Override
100                        public String next() {
101                                return words.inverse().get(indexes[index++]);
102                        }
103
104                        @Override
105                        public boolean hasNext() {
106                                return index<indexes.length;
107                        }
108                };
109        }
110
111        @Override
112        public String toString() {
113                String ret = "[";
114                for (String word : this) {
115                        double wordWeight = this.wordWeights.getElement(this.words.get(word));
116                        ret += String.format("%s (%1.4f)",word,wordWeight) + ", ";
117                }
118                ret += "]";
119                return ret;
120        }
121
122}