Multi-term named entities in Stanford Named Entity Recognizer

Question

I\'m using the Stanford Named Entity Recognizer http://nlp.stanford.edu/software/CRF-NER.shtml and it\'s working fine. This is

    List&         


        

Answer 1

List<List<CoreLabel>> out = classifier.classify(text);
for (List<CoreLabel> sentence : out) {
    String s = "";
    String prevLabel = null;
    for (CoreLabel word : sentence) {
      if(prevLabel == null  || prevLabel.equals(word.get(CoreAnnotations.AnswerAnnotation.class)) ) {
         s = s + " " + word;
         prevLabel = word.get(CoreAnnotations.AnswerAnnotation.class);
      }
      else {
        if(!prevLabel.equals("O"))
           System.out.println(s.trim() + '/' + prevLabel + ' ');
        s = " " + word;
        prevLabel = word.get(CoreAnnotations.AnswerAnnotation.class);
      }
    }
    if(!prevLabel.equals("O"))
        System.out.println(s + '/' + prevLabel + ' ');
}

I just wrote a small logic and it's working fine. what I did is group words with same label if they are adjacent.

Answer 2

The counterpart of the classifyToCharacterOffsets method is that (AFAIK) you can't access the label of the entities.

As proposed by Christopher, here is an example of a loop which assembles "adjacent non-O things". This example also counts the number of occurrences.

public HashMap<String, HashMap<String, Integer>> extractEntities(String text){

    HashMap<String, HashMap<String, Integer>> entities =
            new HashMap<String, HashMap<String, Integer>>();

    for (List<CoreLabel> lcl : classifier.classify(text)) {

        Iterator<CoreLabel> iterator = lcl.iterator();

        if (!iterator.hasNext())
            continue;

        CoreLabel cl = iterator.next();

        while (iterator.hasNext()) {
            String answer =
                    cl.getString(CoreAnnotations.AnswerAnnotation.class);

            if (answer.equals("O")) {
                cl = iterator.next();
                continue;
            }

            if (!entities.containsKey(answer))
                entities.put(answer, new HashMap<String, Integer>());

            String value = cl.getString(CoreAnnotations.ValueAnnotation.class);

            while (iterator.hasNext()) {
                cl = iterator.next();
                if (answer.equals(
                        cl.getString(CoreAnnotations.AnswerAnnotation.class)))
                    value = value + " " +
                           cl.getString(CoreAnnotations.ValueAnnotation.class);
                else {
                    if (!entities.get(answer).containsKey(value))
                        entities.get(answer).put(value, 0);

                    entities.get(answer).put(value,
                            entities.get(answer).get(value) + 1);

                    break;
                }
            }

            if (!iterator.hasNext())
                break;
        }
    }

    return entities;
}