observationvectorreader.java

java实现的隐马尔科夫模型

/* jahmm package - v0.3.1 */

/*
 *  Copyright (c) 2004, Jean-Marc Francois.
 *
 *  This file is part of Jahmm.
 *  Jahmm 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.
 *
 *  Jahmm 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 Jahmm; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package be.ac.ulg.montefiore.run.jahmm.io;

import java.util.*;
import java.io.*;
import be.ac.ulg.montefiore.run.jahmm.*;


/**
 * Reads an {@link be.ac.ulg.montefiore.run.jahmm.ObservationVector
 * ObservationVector} up to (and including) a semi-colon.
 * <p>
 * The format of this observation is an opening bracket (<tt>[</tt>) followed
 * by the components of the vector separated by spaces or tabs.  Each
 * component is a number ([+-]?[0123456789]+[.]?[0123456789]*).
 * <p>
 * For example, reading
 * <pre>[76 45. -2.23];</pre>
 * creates an observation such as the one generated by
 * <code>new ObservationVector(new double[] {76., 45., -2.23});</code>
 */
public class ObservationVectorReader
    extends ObservationReader {
    
    private int dimension;
    
    
    /**
     * Constructs a reader of {@link ObservationVector ObservationVector}.
     */
    public ObservationVectorReader() {
	dimension = -1;
    }
    
    
    /**
     * Constructs a reader of {@link ObservationVector ObservationVector}.
     * Verifies the dimension of the observations read.
     *
     * @param dimension The dimension of each observation.
     */
    public ObservationVectorReader(int dimension) {
	if (dimension <= 0)
	    throw new IllegalArgumentException();

	this.dimension = dimension;
    }

    
    /**
     * An {@link be.ac.ulg.montefiore.run.jahmm.ObservationInteger
     * ObservationInteger} reader, as explained in 
     * {@link ObservationReader ObservationReader}.
     *
     * @param st A stream tokenizer.
     * @return An {@link be.ac.ulg.montefiore.run.jahmm.ObservationInteger
     *         ObservationInteger}.
     */
    public Observation read(StreamTokenizer st) 
	throws IOException, FileFormatException {
	
	switch (st.nextToken()) {
	case '[':
	    break;
	    
	default:
	    throw new FileFormatException("'[' expected");
	}

	Vector values = new Vector();
	
	    loop: 
	while(true)
	    switch (st.nextToken()) {
	    case StreamTokenizer.TT_NUMBER:
		values.add(new Double(st.nval));
		break;
		
	    case ']':
		if (values.size() == 0)
		    throw new FileFormatException("Empty vector found");
		break loop;
		
	    default:
		throw new FileFormatException("Number or ']' expected");
	    }
	
	switch (st.nextToken()) {
	case ';':
	    break;
	    
	default:
	    throw new FileFormatException("';' expected");
	}

	if (dimension > 0 && values.size() != dimension)
	    throw new FileFormatException("Bad observation: wrong dimension");

	double[] doubleValues = new double[values.size()];
	for (int i = 0; i < values.size(); i++)
	    doubleValues[i] = ((Double) values.elementAt(i)).doubleValue();

	return new ObservationVector(doubleValues);
    }
}