/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 opennlp.tools.util.featuregen;
import java.util.List;
public class PosTaggerFeatureGenerator implements AdaptiveFeatureGenerator {
private final String SB = "S=begin";
@Override
public void createFeatures(List<String> features, String[] tokens, int index,
String[] tags) {
String prev, prevprev = null;
String tagprev, tagprevprev;
tagprev = tagprevprev = null;
if (index - 1 >= 0) {
prev = tokens[index - 1];
tagprev = tags[index - 1];
if (index - 2 >= 0) {
prevprev = tokens[index - 2];
tagprevprev = tags[index - 2];
}
else {
prevprev = SB;
}
}
else {
prev = SB;
}
// add the words and pos's of the surrounding context
if (prev != null) {
if (tagprev != null) {
features.add("t=" + tagprev);
}
if (prevprev != null) {
if (tagprevprev != null) {
features.add("t2=" + tagprevprev + "," + tagprev);
}
}
}
}
}