/* Copyright (C) 2002 Univ. of Massachusetts Amherst, Computer Science Dept.
This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
http://www.cs.umass.edu/~mccallum/mallet
This software is provided under the terms of the Common Public License,
version 1.0, as published by http://www.opensource.org. For further
information, see the file `LICENSE' included with this distribution. */
package cc.mallet.pipe;
import cc.mallet.types.Alphabet;
import cc.mallet.types.Instance;
import cc.mallet.types.Label;
import cc.mallet.types.LabelAlphabet;
/** Convert object in the target field into a label in the target field.
@author Andrew McCallum <a href="mailto:mccallum@cs.umass.edu">mccallum@cs.umass.edu</a>
*/
public class Target2Label extends Pipe
{
private final static long serialVersionUID = -461155063551297878L; //-8390758647439705273L;
// gsc: adding constructor that has an option for the data alphabet as well,
// this avoids the data alphabet getting set to null towards the end of a
// SerialPipes object because the data alphabet might have already been set
public Target2Label (Alphabet dataAlphabet, LabelAlphabet labelAlphabet) {
super(dataAlphabet, labelAlphabet);
}
public Target2Label ()
{
this(null, new LabelAlphabet());
}
public Target2Label (LabelAlphabet labelAlphabet)
{
this(null, labelAlphabet);
}
public Instance pipe (Instance carrier)
{
if (carrier.getTarget() != null) {
if (carrier.getTarget() instanceof Label)
throw new IllegalArgumentException ("Already a label.");
LabelAlphabet ldict = (LabelAlphabet) getTargetAlphabet();
carrier.setTarget(ldict.lookupLabel (carrier.getTarget()));
}
return carrier;
}
}