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Lucene example source code file (QualityStats.java)

This example Lucene source code file (QualityStats.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

arraylist, good, illegalargumentexception, io, m, m, num, points, qualitystats, qualitystats, recallpoint, recallpoint, seconds, string, string, text, util

The Lucene QualityStats.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.lucene.benchmark.quality;

import java.io.PrintWriter;
import java.text.NumberFormat;
import java.util.ArrayList;

/**
 * Results of quality benchmark run for a single query or for a set of queries.
 */
public class QualityStats {

  /** Number of points for which precision is computed. */
  public static final int MAX_POINTS = 20;
  
  private double maxGoodPoints;
  private double recall;
  private double pAt[];
  private double pReleventSum = 0;
  private double numPoints = 0;
  private double numGoodPoints = 0;
  private double mrr = 0;
  private long searchTime;
  private long docNamesExtractTime;

  /**
   * A certain rank in which a relevant doc was found.
   */
  public static class RecallPoint {
    private int rank;
    private double recall;
    private RecallPoint(int rank, double recall) {
      this.rank = rank;
      this.recall = recall;
    }
    /** Returns the rank: where on the list of returned docs this relevant doc appeared. */
    public int getRank() {
      return rank;
    }
    /** Returns the recall: how many relevant docs were returned up to this point, inclusive. */
    public double getRecall() {
      return recall;
    }
  }
  
  private ArrayList<RecallPoint> recallPoints;
  
  /**
   * Construct a QualityStats object with anticipated maximal number of relevant hits. 
   * @param maxGoodPoints maximal possible relevant hits.
   */
  public QualityStats(double maxGoodPoints, long searchTime) {
    this.maxGoodPoints = maxGoodPoints;
    this.searchTime = searchTime;
    this.recallPoints = new ArrayList<RecallPoint>();
    pAt = new double[MAX_POINTS+1]; // pAt[0] unused. 
  }

  /**
   * Add a (possibly relevant) doc.
   * @param n rank of the added doc (its ordinal position within the query results).
   * @param isRelevant true if the added doc is relevant, false otherwise.
   */
  public void addResult(int n, boolean isRelevant, long docNameExtractTime) {
    if (Math.abs(numPoints+1 - n) > 1E-6) {
      throw new IllegalArgumentException("point "+n+" illegal after "+numPoints+" points!");
    }
    if (isRelevant) {
      numGoodPoints+=1;
      recallPoints.add(new RecallPoint(n,numGoodPoints));
      if (recallPoints.size()==1 && n<=5) { // first point, but only within 5 top scores. 
        mrr =  1.0 / n;
      }
    }
    numPoints = n;
    double p = numGoodPoints / numPoints;
    if (isRelevant) {
      pReleventSum += p;
    }
    if (n<pAt.length) {
      pAt[n] = p;
    }
    recall = maxGoodPoints<=0 ? p : numGoodPoints/maxGoodPoints;
    docNamesExtractTime += docNameExtractTime;
  }

  /**
   * Return the precision at rank n:
   * |{relevant hits within first <code>n hits}| / n.
   * @param n requested precision point, must be at least 1 and at most {@link #MAX_POINTS}. 
   */
  public double getPrecisionAt(int n) {
    if (n<1 || n>MAX_POINTS) {
      throw new IllegalArgumentException("n="+n+" - but it must be in [1,"+MAX_POINTS+"] range!"); 
    }
    if (n>numPoints) {
      return (numPoints * pAt[(int)numPoints])/n;
    }
    return pAt[n];
  }

  /**
   * Return the average precision at recall points.
   */
  public double getAvp() {
    return maxGoodPoints==0 ? 0 : pReleventSum/maxGoodPoints;
  }
  
  /**
   * Return the recall: |{relevant hits found}| / |{relevant hits existing}|.
   */
  public double getRecall() {
    return recall;
  }

  /**
   * Log information on this QualityStats object.
   * @param logger Logger.
   * @param prefix prefix before each log line.
   */
  public void log(String title, int paddLines, PrintWriter logger, String prefix) {
    for (int i=0; i<paddLines; i++) {  
      logger.println();
    }
    if (title!=null && title.trim().length()>0) {
      logger.println(title);
    }
    prefix = prefix==null ? "" : prefix;
    NumberFormat nf = NumberFormat.getInstance();
    nf.setMaximumFractionDigits(3);
    nf.setMinimumFractionDigits(3);
    nf.setGroupingUsed(true);
    int M = 19;
    logger.println(prefix+format("Search Seconds: ",M)+
        fracFormat(nf.format((double)searchTime/1000)));
    logger.println(prefix+format("DocName Seconds: ",M)+
        fracFormat(nf.format((double)docNamesExtractTime/1000)));
    logger.println(prefix+format("Num Points: ",M)+
        fracFormat(nf.format(numPoints)));
    logger.println(prefix+format("Num Good Points: ",M)+
        fracFormat(nf.format(numGoodPoints)));
    logger.println(prefix+format("Max Good Points: ",M)+
        fracFormat(nf.format(maxGoodPoints)));
    logger.println(prefix+format("Average Precision: ",M)+
        fracFormat(nf.format(getAvp())));
    logger.println(prefix+format("MRR: ",M)+
        fracFormat(nf.format(getMRR())));
    logger.println(prefix+format("Recall: ",M)+
        fracFormat(nf.format(getRecall())));
    for (int i=1; i<(int)numPoints && i where r is the 
   * rank of the first correct result, or <code>0 if there are no correct 
   * results within the top 5 results. 
   * <p>
   * This follows the definition in 
   * <a href="http://www.cnlp.org/publications/02cnlptrec10.pdf"> 
   * Question Answering - CNLP at the TREC-10 Question Answering Track</a>.
   */
  public double getMRR() {
    return mrr;
  }

  
  /**
   * Returns the search time in milliseconds for the measured query.
   */
  public long getSearchTime() {
    return searchTime;
  }

}

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