amqueryexpand.java

自己写的search engine, 有 boolean search, fuzzy search

package searchingEngine.queryExpansion;

import java.io.*;
import java.util.*;

import searchingEngine.dataPreprocessing.invertedFile.TermNode;
import searchingEngine.utilites.dataConverter.RawConverter;
import searchingEngine.utilites.sorting.*;

public class AMQueryExpand
{
	static final double threshould = 0.5;
	static final int topXterms = 2;
	LinkedList<TermNode> termList;
	AssociationMartix am;

	static{
		try{
			// get association matrix
			termList = (LinkedList<TermNode>)RawConverter.loadObject("combined0.dat");
			am = new AssociationMartix(termList.size());
			am.generateAssoMat(termList,IS_METRIC);
			System.out.println("AssociationMartix:");
			RawConverter.saveObject(am,"am0.dat");
		} catch(Exception ex){ ex.printStackTrace(); }
	}

	public String[] getAssociatedTerm(String term, boolean topRankMethod)
	{
		if(topRankMethod) return topRanking(term);
		else return thresholding(term);
	}

	private String[] topRanking(String term)
	{
		int termIndex = Collections.binarySearch(termList, term);
		Hashtable resultValue = new Hashtable();
		double Sij;

		for(int i=0; i<termList.size(); i++)
		{
			if(i<termIndex)				Sij = am.getValueAt(termIndex, i);
			else if(i>termIndex)	Sij = am.getValueAt(i, termIndex);
			else									Sij = -1;

			if(Sij>0)
				resultValue.put(termList.get(i).term, Sij);
		}

		String[] result = new String[topXterms];
		double[] topValues = new double[topXterms];
		for(int i=0; i<topXterms; i++)
			topValues[i] = 0;
		for(Enumeration e=resultValue.keys(); e.hasMoreElements(); )
		{
			String term = (String)e.nextElement();
			double value = ((Float)resultValue.get(term)).doubleValue();
			for(int i=0; i<topXterms; i++)
			{
				if(value>topValues[i])
				{
					for(j=topXterms-1; j>i; j--)
						topValues[j] = topValues[j-1];
					topValues[i] = value;
					result[i] = term;
					break;
				}
			}
		}
		return (result!=null?result:new String[0]);
	}

	private String[] thresholding(String term)
	{
		int termIndex = Collections.binarySearch(termList, term);
		Vector result = new Vector();
		double Sij;

		for(int i=0; i<termList.size(); i++)
		{
			if(i<termIndex)				Sij = am.getValueAt(termIndex, i);
			else if(i>termIndex)	Sij = am.getValueAt(i, termIndex);
			else									Sij = -1;

			if(Sij>0 && Sij>threshould)
				result.add(termList.get(i).term);
		}
		return (result!=null?(String[])result.toArray(new String[0]):new String[0]);
	}
}