opennlp.tools.util.featuregen.TrigramNameFeatureGenerator Maven / Gradle / Ivy
/*
* 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;
/**
* Adds trigram features based on tokens and token classes.
*
*/
public class TrigramNameFeatureGenerator implements AdaptiveFeatureGenerator {
public void createFeatures(List features, String[] tokens, int index,
String[] previousOutcomes) {
String wc = FeatureGeneratorUtil.tokenFeature(tokens[index]);
// trigram features
if (index > 1) {
features.add("ppw,pw,w=" + tokens[index - 2] + "," + tokens[index - 1] + "," + tokens[index]);
String pwc = FeatureGeneratorUtil.tokenFeature(tokens[index - 1]);
String ppwc = FeatureGeneratorUtil.tokenFeature(tokens[index - 2]);
features.add("ppwc,pwc,wc=" + ppwc + "," + pwc + "," + wc);
}
if (index + 2 < tokens.length) {
features.add("w,nw,nnw=" + tokens[index] + "," + tokens[index + 1] + "," + tokens[index + 2]);
String nwc = FeatureGeneratorUtil.tokenFeature(tokens[index + 1]);
String nnwc = FeatureGeneratorUtil.tokenFeature(tokens[index + 2]);
features.add("wc,nwc,nnwc=" + wc + "," + nwc + "," + nnwc);
}
}
}