gismodelreader.java

垃圾邮件过滤器源代码

///////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2001 Jason Baldridge and Gann Bierner
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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 Lesser General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//////////////////////////////////////////////////////////////////////////////
package opennlp.maxent.io;

import java.util.StringTokenizer;

import opennlp.maxent.GISModel;
import opennlp.maxent.TIntParamHashMap;

/**
 * Abstract parent class for readers of GISModels.
 *
 * @author      Jason Baldridge
 * @version     $Revision: 1.5 $, $Date: 2004/06/11 20:51:36 $
 */
public abstract class GISModelReader {
    // The number of predicates contained in the model.
    protected int NUM_PREDS;

    // Implement as needed for the format the model is stored in.
    protected abstract int readInt () throws java.io.IOException;

    /**
     * Implement as needed for the format the model is stored in.
     */
    protected abstract double readDouble () throws java.io.IOException;

    /**
     * Implement as needed for the format the model is stored in.
     */
    protected abstract String readUTF () throws java.io.IOException;

    /**
     * 从磁盘文件获得一个模型，下面是模型参数的存储顺序：
     * Retrieve a model from disk. It assumes that models are saved in the
     * following sequence:
     *
     * <br>GIS (model type identifier)  模型类型识别
     * <br>1. # of parameters (int)
     * <br>2. the correction constant (int)
     * <br>3. the correction constant parameter (double)
     * <br>4. # of outcomes (int)
     * <br>  * list of outcome names (String)
     * <br>5. # of different types of outcome patterns (int)
     * <br>   * list of (int int[])
     * <br>   [# of predicates for which outcome pattern is true] [outcome pattern]
     * <br>6. # of predicates (int)
     * <br>   * list of predicate names (String)
     *
     * <p>If you are creating a reader for a format which won't work with this
     * (perhaps a database or xml file), override this method and ignore the
     * other methods provided in this abstract class.
     *
     * @return The GISModel stored in the format and location specified to
     *         this GISModelReader (usually via its the constructor).
     */
    public GISModel getModel () throws java.io.IOException {
        checkModelType();
        double correctionConstant = getCorrectionConstant();  //校正常量C
        double correctionParam = getCorrectionParameter();  //校正参数
        String[] outcomeLabels = getOutcomes();   //输出结果的名字
        int[][] outcomePatterns = getOutcomePatterns();  //输出结果对应情况
        String[] predLabels = getPredicates();
        TIntParamHashMap[] params = getParameters(outcomePatterns);

        return new GISModel(params,predLabels,outcomeLabels,correctionConstant,correctionParam);
    }

    protected void checkModelType () throws java.io.IOException {
        String modelType = readUTF();
        if (!modelType.equals("GIS"))
            System.out.println("Error: attempting to load a "+modelType+
                               " model as a GIS model." + "You should expect problems.");
    }

    protected double getCorrectionConstant () throws java.io.IOException {
        return readDouble();
    }

    protected double getCorrectionParameter () throws java.io.IOException {
        return readDouble();
    }

    protected String[] getOutcomes () throws java.io.IOException {
        int numOutcomes = readInt();
        String[] outcomeLabels = new String[numOutcomes];
        for (int i=0; i<numOutcomes; i++) outcomeLabels[i] = readUTF();
        return outcomeLabels;
    }

    protected int[][] getOutcomePatterns () throws java.io.IOException {
        int numOCTypes = readInt();  //输出结果类型的个数
        int[][] outcomePatterns = new int[numOCTypes][];
        for (int i=0; i<numOCTypes; i++) {
            StringTokenizer tok = new StringTokenizer(readUTF(), " ");
            int[] infoInts = new int[tok.countTokens()];
            for (int j = 0; tok.hasMoreTokens(); j++) {
                infoInts[j] = Integer.parseInt(tok.nextToken());
            }
            outcomePatterns[i] = infoInts;
        }
        return outcomePatterns;
    }

    protected String[] getPredicates () throws java.io.IOException {
      NUM_PREDS = readInt();   //谓词的个数
      String[] predLabels = new String[NUM_PREDS];
      for (int i = 0; i < NUM_PREDS; i++)
        predLabels[i] = readUTF();
      return predLabels;
    }

    protected TIntParamHashMap[] getParameters (int[][] outcomePatterns)
        throws java.io.IOException {

      // 双重HASH表
        TIntParamHashMap[] params = new TIntParamHashMap[NUM_PREDS];

        int pid=0;
        for (int i=0; i<outcomePatterns.length; i++) {
            for (int j=0; j<outcomePatterns[i][0]; j++) {
                params[pid] = new TIntParamHashMap();
                for (int k=1; k<outcomePatterns[i].length; k++) {
                    double d = readDouble();
                    params[pid].put(outcomePatterns[i][k], d);
                }
                params[pid].compact();
                pid++;
            }
        }
        return params;
    }
}