/*
* 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.namefind;
import java.util.ArrayList;
import java.util.List;
import opennlp.tools.util.featuregen.AdaptiveFeatureGenerator;
import opennlp.tools.util.featuregen.BigramNameFeatureGenerator;
import opennlp.tools.util.featuregen.CachedFeatureGenerator;
import opennlp.tools.util.featuregen.FeatureGeneratorUtil;
import opennlp.tools.util.featuregen.OutcomePriorFeatureGenerator;
import opennlp.tools.util.featuregen.PreviousMapFeatureGenerator;
import opennlp.tools.util.featuregen.TokenClassFeatureGenerator;
import opennlp.tools.util.featuregen.TokenFeatureGenerator;
import opennlp.tools.util.featuregen.WindowFeatureGenerator;
/**
* Class for determining contextual features for a tag/chunk style
* named-entity recognizer.
*/
public class DefaultNameContextGenerator implements NameContextGenerator {
private AdaptiveFeatureGenerator featureGenerators[];
@Deprecated
private static AdaptiveFeatureGenerator windowFeatures = new CachedFeatureGenerator(
new AdaptiveFeatureGenerator[]{
new WindowFeatureGenerator(new TokenFeatureGenerator(), 2, 2),
new WindowFeatureGenerator(new TokenClassFeatureGenerator(true), 2, 2),
new OutcomePriorFeatureGenerator(),
new PreviousMapFeatureGenerator(),
new BigramNameFeatureGenerator()
});
/**
* Creates a name context generator.
* @deprecated use the other constructor and always provide the feature generators
*/
@Deprecated
public DefaultNameContextGenerator() {
this((AdaptiveFeatureGenerator[]) null);
}
/**
* Creates a name context generator with the specified cache size.
*/
public DefaultNameContextGenerator(AdaptiveFeatureGenerator... featureGenerators) {
if (featureGenerators != null) {
this.featureGenerators = featureGenerators;
}
else {
// use defaults
this.featureGenerators = new AdaptiveFeatureGenerator[]{
windowFeatures,
new PreviousMapFeatureGenerator()};
}
}
public void addFeatureGenerator(AdaptiveFeatureGenerator generator) {
AdaptiveFeatureGenerator generators[] = featureGenerators;
featureGenerators = new AdaptiveFeatureGenerator[featureGenerators.length + 1];
System.arraycopy(generators, 0, featureGenerators, 0, generators.length);
featureGenerators[featureGenerators.length - 1] = generator;
}
public void updateAdaptiveData(String[] tokens, String[] outcomes) {
if (tokens != null && outcomes != null && tokens.length != outcomes.length) {
throw new IllegalArgumentException(
"The tokens and outcome arrays MUST have the same size!");
}
for (AdaptiveFeatureGenerator featureGenerator : featureGenerators) {
featureGenerator.updateAdaptiveData(tokens, outcomes);
}
}
public void clearAdaptiveData() {
for (AdaptiveFeatureGenerator featureGenerator : featureGenerators) {
featureGenerator.clearAdaptiveData();
}
}
/**
* Return the context for finding names at the specified index.
* @param index The index of the token in the specified toks array for which the context should be constructed.
* @param tokens The tokens of the sentence. The <code>toString</code> methods of these objects should return the token text.
* @param preds The previous decisions made in the tagging of this sequence. Only indices less than i will be examined.
* @param additionalContext Addition features which may be based on a context outside of the sentence.
*
* @return the context for finding names at the specified index.
*/
public String[] getContext(int index, String[] tokens, String[] preds, Object[] additionalContext) {
List<String> features = new ArrayList<String>();
for (AdaptiveFeatureGenerator featureGenerator : featureGenerators) {
featureGenerator.createFeatures(features, tokens, index, preds);
}
//previous outcome features
String po = NameFinderME.OTHER;
String ppo = NameFinderME.OTHER;
if (index > 1){
ppo = preds[index-2];
}
if (index > 0) {
po = preds[index-1];
}
features.add("po=" + po);
features.add("pow=" + po + "," + tokens[index]);
features.add("powf=" + po + "," + FeatureGeneratorUtil.tokenFeature(tokens[index]));
features.add("ppo=" + ppo);
return features.toArray(new String[features.size()]);
}
}