minheap.java

一个很好的LIBSVM的JAVA源码。对于要研究和改进SVM算法的学者。可以参考。来自数据挖掘工具YALE工具包。

/*
 *  YALE - Yet Another Learning Environment
 *  Copyright (C) 2001-2004
 *      Simon Fischer, Ralf Klinkenberg, Ingo Mierswa, 
 *          Katharina Morik, Oliver Ritthoff
 *      Artificial Intelligence Unit
 *      Computer Science Department
 *      University of Dortmund
 *      44221 Dortmund,  Germany
 *  email: [e-mail]
 *  web:   http://yale.cs.uni-dortmund.de/
 *
 *  This program 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. 
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA.
 */
package edu.udo.cs.mySVM.Util;

/**
 * Implements a MinHeap on n doubles and ints
 * @author Stefan R?ping
 * @version 1.0
 */
public class MinHeap extends Heap {

    public MinHeap(int n){
	the_size = 0;
	init(n);
    };


    public final void add(double value, int index)
    {
	if(last < the_size){
	    heap[last] = value;
	    indizes[last] = index;
	    last++;
	    if(last == the_size){
		for(int j=last;j>0;j--){
		    heapify(j-1,last+1-j);
		};
	    };
	}
	else if(value < heap[0]){
	    heap[0] = value;
	    indizes[0] = index;
	    heapify(0,last);
	};
    };


    protected final void heapify(int start, int size)
    {
	double[] my_heap = heap;
	boolean running = true;
	int pos = 1;
	int left, right, largest;
	double dummyf;
	int dummyi;
	start--;  // other variables counted from 1
	while(running){
	    left = 2*pos;
	    right = left+1;
	    if((left<=size) && 
	       (my_heap[left+start] > my_heap[start+pos])){
		largest = left;
	    }
	    else{
		largest = pos;
	    };
	    if((right<=size) && 
	       (my_heap[start+right] > my_heap[start+largest])){
		largest = right;
	    };
	    if(largest == pos){
		running = false;
	    }
	    else{
		dummyf = my_heap[start+pos];
		dummyi = indizes[start+pos];
		my_heap[start+pos] = my_heap[start+largest];
		indizes[start+pos] = indizes[start+largest];
		my_heap[start+largest] = dummyf;
		indizes[start+largest] = dummyi;
		pos = largest;
	    };
	};
    };
};