simplepremise.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.yale.operator.learner.decisiontree;

import edu.udo.cs.yale.example.Attribute;
import edu.udo.cs.yale.example.Example;
import edu.udo.cs.yale.tools.LogService;

/** A premise is a condition for a rule.
 *
 *  @author Ingo
 *  @version $Id: SimplePremise.java,v 2.3 2004/08/27 11:57:38 ingomierswa Exp $
 */
public class SimplePremise extends Premise {

    private String operator;
    private double value;

    private static final String OPERATORS[] = { "=", "<", ">", ">=", "<=" };

    public SimplePremise(Attribute attribute, String operator, double value) {
	super(attribute);
	this.operator = operator;
	this.value = value;
	
	boolean operatorOk = false;
	for (int i = 0; i < OPERATORS.length; i++) {
	    if (OPERATORS[i].equals(operator)) operatorOk = true;
	}
	if (!operatorOk) throw new IllegalArgumentException("Illegal operator for premise: '"+operator+"'");
    }

    public boolean isTrue(Example example) {
	if (operator.equals("=")) {
	    return (value == example.getValue(getAttribute()));
	} else if (operator.equals(">")) {
	    return (value > example.getValue(getAttribute()));
	} else if (operator.equals("<")) {
	    return (value < example.getValue(getAttribute()));
	} else if (operator.equals(">=")) {
	    return (value >= example.getValue(getAttribute()));
	} else if (operator.equals("<=")) {
	    return (value <= example.getValue(getAttribute()));
	} else {
	    LogService.logMessage("Wrong operator for numerical premise: " + operator, 
				  LogService.WARNING);
	    return false;
	}
    }

    public String getTreeEdgeString() {
	String operator = this.operator;

	if (operator.equals("=")) operator = "";
	else if (operator.equals("<=")) operator = "\u2264";
	else if (operator.equals(">=")) operator = "\u2265";
	
	return operator + getAttribute().getAsString(value);
    }

    public String toString() {
	Attribute attribute = getAttribute();
	return attribute.getName() + " " + operator + " " + attribute.getAsString(value);
    }

}