randomfilter.java

一个用于排队系统仿真的开源软件,有非常形象的图象仿真过程!

/**    
  * Copyright (C) 2006, Laboratorio di Valutazione delle Prestazioni - Politecnico di Milano

  * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
package jmt.engine.jwat.filters;

import jmt.engine.jwat.Observation;
import jmt.engine.random.engine.MersenneTwister;

public class RandomFilter implements FilterOnVariable {
	private boolean[] matcher = null;
	public RandomFilter(int total, int nObs){
		generateRandom(total,nObs,matcher = new boolean[total]);
	}
	
	public boolean isMatching(Observation o, int pos) {
		return matcher[pos];
	}
	
	private int generateRandom(int numTotal,int numToRead,boolean[] catchVal)
	{
		int[] rndArray=new int[numTotal];
		int max=0,i,dimArray,rndNum;
		MersenneTwister mst=new MersenneTwister();
		
		dimArray=numTotal;
		for(i=0;i<dimArray;i++) rndArray[i]=i;
		
		for(i=0;i<numToRead;i++)
		{
			rndNum= (int) (mst.nextDouble()*dimArray);
			catchVal[rndArray[rndNum]]= true;
			if(max<rndArray[rndNum]) max=rndArray[rndNum];
			rndArray[rndNum]=rndArray[--dimArray];
		}
		
		return max;
	}
}