/* 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 CountMatchesAlignedWithOffsets extends Pipe
{
Pattern regex;
String feature;
int[] offsets;
boolean normalizeByMatchCount = false;
public CountMatchesAlignedWithOffsets (String featureName,
Pattern regex, int[] offsets,
boolean normalizeByMatchCount)
{
this.feature = featureName;
this.regex = regex;
this.offsets = offsets;
this.normalizeByMatchCount = normalizeByMatchCount;
}
public CountMatchesAlignedWithOffsets (String featureName,
Pattern regex, int[] offsets)
{
this (featureName, regex, offsets, false);
}
public Instance pipe (Instance carrier)
{
TokenSequence ts = (TokenSequence) carrier.getData();
int countMatches;
int countAlignedMatches;
for (int i = 0; i < ts.size(); i++) {
countMatches = 0;
countAlignedMatches = 0;
Token t = ts.get(i);
Matcher matcher = regex.matcher (t.getText());
while (matcher.find ()) {
countMatches++;
int position = matcher.start();
for (int j = 0; j < offsets.length; j++) {
int offset = i + offsets[j];
if (offset >= 0 && offset < ts.size()) {
String offsetText = ts.get(offset).getText();
if (offsetText.length() > position) {
Matcher offsetMatcher =
regex.matcher (offsetText.substring(position));
if (offsetMatcher.lookingAt())
countAlignedMatches++;
}
}
}
}
if (countAlignedMatches > 0)
t.setFeatureValue (feature, (normalizeByMatchCount
? ((double)countAlignedMatches)/countMatches
: (double)countAlignedMatches));
}
return carrier;
}
}