constantgenerator.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.generator;

import edu.udo.cs.yale.example.Attribute;
import edu.udo.cs.yale.example.DataRow;
import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.example.ExampleTable;
import edu.udo.cs.yale.tools.Ontology;

import java.util.List;
import java.util.ArrayList;

public class ConstantGenerator extends FeatureGenerator {

    public static final String FUNCTION_NAME = "const";

    private double constant = 1.0d;
    private String constantString = "1";
    
    public ConstantGenerator() {}
    
    public ConstantGenerator(double constant) {
	this.constant = constant;
	this.constantString = constant + "";
    }

    public void setArguments(Attribute[] args) {

    }

    public FeatureGenerator newInstance() {
	return new ConstantGenerator();
    }

    public String getFunction() {
	return FUNCTION_NAME + "[" + constantString + "]";
    }
    
    public void setFunction(String functionName) {
	int leftIndex = functionName.indexOf("[");
	int rightIndex = functionName.indexOf("]");
	if ((leftIndex != -1) && (rightIndex != -1)) {
	    this.constantString = functionName.substring(leftIndex+1, rightIndex);
	    this.constant = Double.parseDouble(constantString);
	}
    }

    public Attribute[] getInputAttributes() {
	return new Attribute[0];
    }

    public Attribute[] getOutputAttributes(ExampleTable input) {
	Attribute ao = new Attribute(Ontology.NUMERICAL, Ontology.SINGLE_VALUE,
				     getFunction(), new Attribute[0], false,
				     Attribute.UNDEFINED_BLOCK_NR,
				     null);
	return new Attribute[] { ao };
    }

    /** Returns all compatible input attribute arrays for this generator from the given example set as list. */
    public List getInputCandidates(ExampleSet exampleSet, int maxDepth, String[] functions) {
	return new ArrayList();
    }

    public void generate(DataRow data) throws GenerationException {
	try {
	    if (resultAttributes[0] != null)
		data.set(resultAttributes[0], constant);
	} catch (ArrayIndexOutOfBoundsException ex) {
  	    throw new GenerationException("a:" + getArgument(0), ex);
  	}
    }

    public String toString() {
	return getFunction();
    }
}