LIRe 源代码分析 3：基本接口（ImageSearcher）
注：此前写了一系列的文章，分析LIRe的源代码，在此列一个列表：
LIRe 源代码分析 1：整体结构
LIRe 源代码分析 2：基本接口（DocumentBuilder）
LIRe 源代码分析 3：基本接口（ImageSearcher）
LIRe 源代码分析 4：建立索引（DocumentBuilder）[以颜色布局为例]
LIRe 源代码分析 5：提取特征向量[以颜色布局为例]
LIRe 源代码分析 6：检索（ImageSearcher）[以颜色布局为例]
LIRe 源代码分析 7：算法类[以颜色布局为例]
上篇文章介绍了LIRe源代码里的DocumentBuilder的几个基本接口：
LIRe 源代码分析 2：基本接口（DocumentBuilder）
本文继续研究一下源代码里的ImageSearcher的几个基本接口。
下面来看看与ImageSearcher相关的类的定义：
ImageSearcher：接口，定义了基本的方法。
AbstractImageSearcher：纯虚类，实现了ImageSearcher接口。
ImageSearcherFactory：用于创建ImageSearcher。
ImageSearcher相关的类的继承关系如下图所示。可见，各种算法类都继承了AbstractImageSearcher，而AbstractImageSearcher实现了ImageSearcher接口。
此外还有一个结构体：
ImageSearchHits：用于存储搜索的结果。
详细的源代码如下所示：
ImageSearcher
/* * This file is part of the LIRe project: http://www.semanticmetadata.net/lire * LIRe 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 2 of the License, or * (at your option) any later version. * * LIRe 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 LIRe; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * We kindly ask you to refer the following paper in any publication mentioning Lire: * * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥� * An Extensible Java CBIR Library. In proceedings of the 16th ACM International * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008 * * http://doi.acm.org/10.1145/1459359.1459577 * * Copyright statement: * -------------------- * (c) 2002-2011 by Mathias Lux ([email protected]) * http://www.semanticmetadata.net/lire */ package net.semanticmetadata.lire; import org.apache.lucene.document.Document; import org.apache.lucene.index.IndexReader; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.InputStream; import java.util.Set; /** * <h2>Searching in an Index</h2> * Use the ImageSearcherFactory for creating an ImageSearcher, which will retrieve the images * for you from the index. * <p/> * <pre> * IndexReader reader = IndexReader.open(indexPath); * ImageSearcher searcher = ImageSearcherFactory.createDefaultSearcher(); * FileInputStream imageStream = new FileInputStream("image.jpg"); * BufferedImage bimg = ImageIO.read(imageStream); * // searching for an image: * ImageSearchHits hits = null; * hits = searcher.search(bimg, reader); * for (int i = 0; i < 5; i++) { * System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue()); * } * * // searching for a document: * Document document = hits.doc(0); * hits = searcher.search(document, reader); * for (int i = 0; i < 5; i++) { * System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue()); * } * </pre> * <p/> * This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net * <br>Date: 01.02.2006 * <br>Time: 00:09:42 * * @author Mathias Lux, [email protected] */ public interface ImageSearcher { /** * Searches for images similar to the given image. * * @param image the example image to search for. * @param reader the IndexReader which is used to dsearch through the images. * @return a sorted list of hits. * @throws java.io.IOException in case exceptions in the reader occurs */ public ImageSearchHits search(BufferedImage image, IndexReader reader) throws IOException; /** * Searches for images similar to the given image, defined by the Document from the index. * * @param doc the example image to search for. * @param reader the IndexReader which is used to dsearch through the images. * @return a sorted list of hits. * @throws java.io.IOException in case exceptions in the reader occurs */ public ImageSearchHits search(Document doc, IndexReader reader) throws IOException; /** * Searches for images similar to the given image. * * @param image the example image to search for. * @param reader the IndexReader which is used to dsearch through the images. * @return a sorted list of hits. * @throws IOException in case the image could not be read from stream. */ public ImageSearchHits search(InputStream image, IndexReader reader) throws IOException; /** * Identifies duplicates in the database. * * @param reader the IndexReader which is used to dsearch through the images. * @return a sorted list of hits. * @throws IOException in case the image could not be read from stream. */ public ImageDuplicates findDuplicates(IndexReader reader) throws IOException; /** * Modifies the given search by the provided positive and negative examples. This process follows the idea * of relevance feedback. * * @param originalSearch * @param positives * @param negatives * @return */ public ImageSearchHits relevanceFeedback(ImageSearchHits originalSearch, Set<Document> positives, Set<Document> negatives); }
从接口的源代码可以看出，提供了5个方法，其中有3个名字都叫search()，只是参数不一样。一个是BufferedImage，一个是Document，而另一个是InputStream。
AbstractImageSearcher
/* * This file is part of the LIRe project: http://www.semanticmetadata.net/lire * LIRe 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 2 of the License, or * (at your option) any later version. * * LIRe 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 LIRe; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * We kindly ask you to refer the following paper in any publication mentioning Lire: * * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥� * An Extensible Java CBIR Library. In proceedings of the 16th ACM International * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008 * * http://doi.acm.org/10.1145/1459359.1459577 * * Copyright statement: * -------------------- * (c) 2002-2011 by Mathias Lux ([email protected]) * http://www.semanticmetadata.net/lire */ package net.semanticmetadata.lire; import org.apache.lucene.document.Document; import org.apache.lucene.index.IndexReader; import javax.imageio.ImageIO; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.InputStream; import java.util.Set; /** * Abstract ImageSearcher, which uses javax.imageio.ImageIO to create a BufferedImage * from an InputStream. * <p/> * This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net * <br>Date: 01.02.2006 * <br>Time: 00:13:16 * * @author Mathias Lux, [email protected] */ public abstract class AbstractImageSearcher implements ImageSearcher { /** * Searches for images similar to the given image. This simple implementation uses * {@link ImageSearcher#search(java.awt.image.BufferedImage, org.apache.lucene.index.IndexReader)}, * the image is read using javax.imageio.ImageIO. * * @param image the example image to search for. * @param reader the IndexReader which is used to dsearch through the images. * @return a sorted list of hits. * @throws IOException in case the image could not be read from stream. */ public ImageSearchHits search(InputStream image, IndexReader reader) throws IOException { BufferedImage bufferedImage = ImageIO.read(image); return search(bufferedImage, reader); } public ImageSearchHits relevanceFeedback(ImageSearchHits originalSearch, Set<Document> positives, Set<Document> negatives) { throw new UnsupportedOperationException("Not implemented yet for this kind of searcher!"); } }
从代码中可以看出AbstractImageSearcher实现了ImageSearcher接口。其中的search(InputStream image, IndexReader reader)方法调用了search(BufferedImage image, IndexReader reader)方法。说白了，就是把2个函数的功能合并为一个函数。
ImageSearcherFactory
/* * This file is part of the LIRe project: http://www.semanticmetadata.net/lire * LIRe 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 2 of the License, or * (at your option) any later version. * * LIRe 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 LIRe; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * We kindly ask you to refer the following paper in any publication mentioning Lire: * * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥� * An Extensible Java CBIR Library. In proceedings of the 16th ACM International * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008 * * http://doi.acm.org/10.1145/1459359.1459577 * * Copyright statement: * ~~~~~~~~~~~~~~~~~~~~ * (c) 2002-2011 by Mathias Lux ([email protected]) * http://www.semanticmetadata.net/lire */ package net.semanticmetadata.lire; import net.semanticmetadata.lire.imageanalysis.*; import net.semanticmetadata.lire.impl.CorrelogramImageSearcher; import net.semanticmetadata.lire.impl.GenericFastImageSearcher; import net.semanticmetadata.lire.impl.SimpleImageSearcher; /** * <h2>Searching in an Index</h2> * Use the ImageSearcherFactory for creating an ImageSearcher, which will retrieve the images * for you from the index. * <p/> * <pre> * IndexReader reader = IndexReader.open(indexPath); * ImageSearcher searcher = ImageSearcherFactory.createDefaultSearcher(); * FileInputStream imageStream = new FileInputStream("image.jpg"); * BufferedImage bimg = ImageIO.read(imageStream); * // searching for an image: * ImageSearchHits hits = null; * hits = searcher.search(bimg, reader); * for (int i = 0; i < 5; i++) { * System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue()); * } * * // searching for a document: * Document document = hits.doc(0); * hits = searcher.search(document, reader); * for (int i = 0; i < 5; i++) { * System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue()); * } * </pre> * <p/> * This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net * <br>Date: 03.02.2006 * <br>Time: 00:30:07 * * @author Mathias Lux, [email protected] */ public class ImageSearcherFactory { /** * Default number of maximum hits. */ public static int NUM_MAX_HITS = 100; /** * Creates a new simple image searcher with the desired number of maximum hits. * * @param maximumHits * @return the searcher instance * @deprecated Use ColorLayout, EdgeHistogram and ScalableColor features instead. */ public static ImageSearcher createSimpleSearcher(int maximumHits) { return ImageSearcherFactory.createColorLayoutImageSearcher(maximumHits); } /** * Returns a new default ImageSearcher with a predefined number of maximum * hits defined in the {@link ImageSearcherFactory#NUM_MAX_HITS} based on the {@link net.semanticmetadata.lire.imageanalysis.CEDD} feature * * @return the searcher instance */ public static ImageSearcher createDefaultSearcher() { return new GenericFastImageSearcher(NUM_MAX_HITS, CEDD.class, DocumentBuilder.FIELD_NAME_CEDD); } /** * Returns a new ImageSearcher with the given number of maximum hits * which only takes the overall color into account. texture and color * distribution are ignored. * * @param maximumHits defining how many hits are returned in max (e.g. 100 would be ok) * @return the ImageSearcher * @see ImageSearcher * @deprecated Use ColorHistogram or ScalableColor instead */ public static ImageSearcher createColorOnlySearcher(int maximumHits) { return ImageSearcherFactory.createScalableColorImageSearcher(maximumHits); } /** * Returns a new ImageSearcher with the given number of maximum hits and * the specified weights on the different matching aspects. All weights * should be in [0,1] whereas a weight of 0 implies that the feature is * not taken into account for searching. Note that the effect is relative and * can only be fully applied if the {@link DocumentBuilderFactory#getExtensiveDocumentBuilder() extensive DocumentBuilder} * is used. * * @param maximumHits defining how many hits are returned in max * @param colorHistogramWeight a weight in [0,1] defining the importance of overall color in the images * @param colorDistributionWeight a weight in [0,1] defining the importance of color distribution (which color where) in the images * @param textureWeight defining the importance of texture (which edges where) in the images * @return the searcher instance or NULL if the weights are not appropriate, eg. all 0 or not in [0,1] * @see DocumentBuilderFactory * @deprecated Use ColorLayout, EdgeHistogram and ScalableColor features instead. */ public static ImageSearcher createWeightedSearcher(int maximumHits, float colorHistogramWeight, float colorDistributionWeight, float textureWeight) { if (isAppropriateWeight(colorHistogramWeight) && isAppropriateWeight(colorDistributionWeight) && isAppropriateWeight(textureWeight) && (colorHistogramWeight + colorDistributionWeight + textureWeight > 0f)) return new SimpleImageSearcher(maximumHits, colorHistogramWeight, colorDistributionWeight, textureWeight); else return null; } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.AutoColorCorrelogram} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits number of hits returned. * @return */ public static ImageSearcher createAutoColorCorrelogramImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, AutoColorCorrelogram.class, DocumentBuilder.FIELD_NAME_AUTOCOLORCORRELOGRAM); // return new CorrelogramImageSearcher(maximumHits, AutoColorCorrelogram.Mode.SuperFast); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.AutoColorCorrelogram} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits number of hits returned. * @return * @deprecated Use #createAutoColorCorrelogramImageSearcher instead */ public static ImageSearcher createFastCorrelogramImageSearcher(int maximumHits) { return new CorrelogramImageSearcher(maximumHits, AutoColorCorrelogram.Mode.SuperFast); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.CEDD} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createCEDDImageSearcher(int maximumHits) { // return new CEDDImageSearcher(maximumHits); return new GenericFastImageSearcher(maximumHits, CEDD.class, DocumentBuilder.FIELD_NAME_CEDD); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.FCTH} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createFCTHImageSearcher(int maximumHits) { // return new GenericImageSearcher(maximumHits, FCTH.class, DocumentBuilder.FIELD_NAME_FCTH); return new GenericFastImageSearcher(maximumHits, FCTH.class, DocumentBuilder.FIELD_NAME_FCTH); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.JCD} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createJCDImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, JCD.class, DocumentBuilder.FIELD_NAME_JCD); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.JpegCoefficientHistogram} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createJpegCoefficientHistogramImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, JpegCoefficientHistogram.class, DocumentBuilder.FIELD_NAME_JPEGCOEFFS); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.SimpleColorHistogram} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createColorHistogramImageSearcher(int maximumHits) { // return new GenericImageSearcher(maximumHits, SimpleColorHistogram.class, DocumentBuilder.FIELD_NAME_COLORHISTOGRAM); return new GenericFastImageSearcher(maximumHits, SimpleColorHistogram.class, DocumentBuilder.FIELD_NAME_COLORHISTOGRAM); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.Tamura} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createTamuraImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, Tamura.class, DocumentBuilder.FIELD_NAME_TAMURA); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.Gabor} * image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createGaborImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, Gabor.class, DocumentBuilder.FIELD_NAME_GABOR); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.ColorLayout} * image feature using the byte[] serialization. Be sure to use the same options for the ImageSearcher as * you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createColorLayoutImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, ColorLayout.class, DocumentBuilder.FIELD_NAME_COLORLAYOUT); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.ScalableColor} * image feature using the byte[] serialization. Be sure to use the same options for the ImageSearcher as * you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createScalableColorImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, ScalableColor.class, DocumentBuilder.FIELD_NAME_SCALABLECOLOR); } /** * Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.EdgeHistogram} * image feature using the byte[] serialization. Be sure to use the same options for the ImageSearcher as * you used for the DocumentBuilder. * * @param maximumHits * @return */ public static ImageSearcher createEdgeHistogramImageSearcher(int maximumHits) { return new GenericFastImageSearcher(maximumHits, EdgeHistogram.class, DocumentBuilder.FIELD_NAME_EDGEHISTOGRAM); } /** * Checks if the weight is in [0,1] * * @param f the weight to check * @return true if the weight is in [0,1], false otherwise */ private static boolean isAppropriateWeight(float f) { boolean result = false; if (f <= 1f && f >= 0) result = true; return result; } }
ImageSearcherFactory是用于创建ImageSearcher的。里面有各种create****ImageSearcher()。每个函数的作用在注释中都有详细的说明。
ImageSearchHits
/* * This file is part of the LIRe project: http://www.semanticmetadata.net/lire * LIRe 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 2 of the License, or * (at your option) any later version. * * LIRe 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 LIRe; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * We kindly ask you to refer the following paper in any publication mentioning Lire: * * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥� * An Extensible Java CBIR Library. In proceedings of the 16th ACM International * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008 * * http://doi.acm.org/10.1145/1459359.1459577 * * Copyright statement: * -------------------- * (c) 2002-2011 by Mathias Lux ([email protected]) * http://www.semanticmetadata.net/lire */ package net.semanticmetadata.lire; import org.apache.lucene.document.Document; /** * This class simulates the original Lucene Hits object. * Please note the only a certain number of results are returned.<br> * <p/> * This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net * <br>Date: 02.02.2006 * <br>Time: 23:45:20 * * @author Mathias Lux, [email protected] */ public interface ImageSearchHits { /** * Returns the size of the result list. * * @return the size of the result list. */ public int length(); /** * Returns the score of the document at given position. * Please note that the score in this case is a distance, * which means a score of 0 denotes the best possible hit. * The result list starts with position 0 as everything * in computer science does. * * @param position defines the position * @return the score of the document at given position. The lower the better (its a distance measure). */ public float score(int position); /** * Returns the document at given position * * @param position defines the position. * @return the document at given position. */ public Document doc(int position); }
该类主要用于存储ImageSearcher类中search()方法返回的结果。
SimpleImageSearchHits是ImageSearcher的实现。该类的源代码如下所示：
/* * This file is part of the LIRe project: http://www.semanticmetadata.net/lire * LIRe 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 2 of the License, or * (at your option) any later version. * * LIRe 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 LIRe; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * We kindly ask you to refer the following paper in any publication mentioning Lire: * * Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥� * An Extensible Java CBIR Library. In proceedings of the 16th ACM International * Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008 * * http://doi.acm.org/10.1145/1459359.1459577 * * Copyright statement: * -------------------- * (c) 2002-2011 by Mathias Lux ([email protected]) * http://www.semanticmetadata.net/lire */ package net.semanticmetadata.lire.impl; import net.semanticmetadata.lire.ImageSearchHits; import org.apache.lucene.document.Document; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; /** * This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net * <br>Date: 02.02.2006 * <br>Time: 23:56:15 * * @author Mathias Lux, [email protected] */ public class SimpleImageSearchHits implements ImageSearchHits { ArrayList<SimpleResult> results; public SimpleImageSearchHits(Collection<SimpleResult> results, float maxDistance) { this.results = new ArrayList<SimpleResult>(results.size()); this.results.addAll(results); // this step normalizes and inverts the distance ... // although its now a score or similarity like measure its further called distance for (Iterator<SimpleResult> iterator = this.results.iterator(); iterator.hasNext(); ) { SimpleResult result = iterator.next(); result.setDistance(1f - result.getDistance() / maxDistance); } } /** * Returns the size of the result list. * * @return the size of the result list. */ public int length() { return results.size(); } /** * Returns the score of the document at given position. * Please note that the score in this case is a distance, * which means a score of 0 denotes the best possible hit. * The result list starts with position 0 as everything * in computer science does. * * @param position defines the position * @return the score of the document at given position. The lower the better (its a distance measure). */ public float score(int position) { return results.get(position).getDistance(); } /** * Returns the document at given position * * @param position defines the position. * @return the document at given position. */ public Document doc(int position) { return results.get(position).getDocument(); } private float sigmoid(float f) { double result = 0f; result = -1d + 2d / (1d + Math.exp(-2d * f / 0.6)); return (float) (1d - result); } }
可以看出检索的结果是存在名为results的ArrayList<SimpleResult> 类型的变量中的。