/* 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. */
/**
Count the number of times the provided regular expression matches
the token text, and add a feature with the provided name having
value equal to the count.
@author Andrew McCallum <a href="mailto:mccallum@cs.umass.edu">mccallum@cs.umass.edu</a>
*/
package cc.mallet.pipe.tsf;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
import cc.mallet.pipe.*;
import cc.mallet.types.*;
public class CountMatches extends Pipe
{
public static final int INTEGER_COUNT = 0;
public static final int BINARY_COUNT = 1;
public static final int NORMALIZED_COUNT = 2;
public static final int OVER_MAX = 3;
Pattern regex;
String feature;
boolean normalizeByCharLength = false;
boolean countIsBinary = false;
public CountMatches (String featureName, Pattern regex, int countType)
{
this.feature = featureName;
this.regex = regex;
if (countType == BINARY_COUNT)
countIsBinary = true;
else if (countType == NORMALIZED_COUNT)
normalizeByCharLength = true;
else if (countType >= OVER_MAX)
throw new IllegalArgumentException ("Bad countType.");
}
public CountMatches (String featureName, Pattern regex)
{
this (featureName, regex, INTEGER_COUNT);
}
public Instance pipe (Instance carrier)
{
TokenSequence ts = (TokenSequence) carrier.getData();
int count;
for (int i = 0; i < ts.size(); i++) {
count = 0;
Token t = ts.get(i);
Matcher matcher = regex.matcher (t.getText());
while (matcher.find ()) {
count++;
if (countIsBinary) break;
}
if (count > 0)
t.setFeatureValue (feature, (normalizeByCharLength
? ((double)count)/t.getText().length()
: (double)count));
}
return carrier;
}
}