eus.ixa.ixa.pipe.nerc.features.FourgramClassFeatureGenerator Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of ixa-pipe-nerc Show documentation

ixa pipes sequence labeler (ixa2.si.ehu.es/ixa-pipes).

There is a newer version: 1.6.1

/*
 * Copyright 2014 Rodrigo Agerri

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */
package eus.ixa.ixa.pipe.nerc.features;

import java.util.List;

import opennlp.tools.util.featuregen.FeatureGeneratorAdapter;

/**
 * Adds fourgram features based on tokens and token class using
 * {@code TokenClassFeatureGenerator}.
 * 
 * @author ragerri
 * 
 */
public class FourgramClassFeatureGenerator extends FeatureGeneratorAdapter {

  public void createFeatures(List features, String[] tokens, int index,
      String[] previousOutcomes) {
    String wc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index]);
    // fourgram features
    if (index > 2) {
      features.add("pppw,ppw,pw,w=" + tokens[index - 3] + "," + tokens[index - 2] + "," + tokens[index - 1] + "," + tokens[index]);
      String pwc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index - 1]);
      String ppwc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index - 2]);
      String pppwc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index - 3]);
      features.add("pppwc,ppwc,pwc,wc=" + pppwc + "," + ppwc + "," + pwc + "," + wc);
    }
    if (index + 3 < tokens.length) {
      features.add("w,nw,nnw,nnnw=" + tokens[index] + "," + tokens[index + 1] + "," + tokens[index + 2] + "," + tokens[index + 3]);
      String nwc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index + 1]);
      String nnwc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index + 2]);
      String nnnwc = TokenClassFeatureGenerator.tokenShapeFeature(tokens[index + 3]);
      features.add("wc,nwc,nnwc,nnnwc=" + wc + "," + nwc + "," + nnwc + "," + nnnwc);
    }
  }
}