opennlp-wsd/src/main/java/opennlp/tools/disambiguator/ims/FeaturesExtractor.java

package opennlp.tools.disambiguator.ims;

import java.util.ArrayList;

import opennlp.tools.disambiguator.Constants;
import opennlp.tools.disambiguator.Loader;


public class FeaturesExtractor {

	
	
	public FeaturesExtractor() {
		super();
	}


	/**
	 * @Algorithm: IMS (It Makes Sense)
	 * 
	 * The following methods serve to extract the features for the algorithm IMS.
	 */
	
	public String[] extractPosOfSurroundingWords (String[] sentence, int wordIndex, int numberOfWords) {
		
		String[] taggedSentence = Loader.getTagger().tag(sentence);
		
		String[] tags = new String[2*numberOfWords+1];
		
		int j = 0;
		
		for (int i = wordIndex - numberOfWords; i < wordIndex + numberOfWords ; i++) {
			if (i < 0 || i >= sentence.length) {
				tags[j] = "null";
			} else {
				tags[j] = taggedSentence[i];
			}
			j++;
		}
		
		return tags;
	}
	
	
	public String[] extractSurroundingWords(String[] sentence, int wordIndex) {

		String[] posTags = Loader.getTagger().tag(sentence);
		
		Constants.print(posTags);
		
		ArrayList<String> contextWords = new ArrayList<String>();

		for (int i = 0; i < sentence.length; i++) {

			if (!Constants.stopWords.contains(sentence[i].toLowerCase())
					&& (wordIndex != i)) {
				
				String word = sentence[i].toLowerCase().replaceAll("[^a-z]", "").trim();
				
				if (!word.equals("")) {
					String lemma = Loader.getLemmatizer().lemmatize(sentence[i], posTags[i]);
					contextWords.add(lemma);
				}
				
				


			}
		}

		return contextWords.toArray(new String[contextWords.size()]);
	}
	
	
	public ArrayList<String[]> extractLocalCollocations(String[] sentence, int wordIndex, int range) {
		/**
		 * Here the author used only 11 features of this type. the range was set to 3 (bigrams extracted in a way that they are at max separated
		 * by 1 word).
		 */
		
		ArrayList<String[]> localCollocations = new ArrayList<String[]>();
		
		for (int i = wordIndex - range; i <= wordIndex + range ; i++) {
			
			if (!(i < 0 || i > sentence.length - 2)) {
					if ((i != wordIndex) && (i+1 != wordIndex) && (i+1 < wordIndex + range)) {
						String[] lc =  {sentence[i], sentence[i+1]};
						localCollocations.add(lc);
					}
					if ((i != wordIndex) && (i+2 != wordIndex) && (i+2 < wordIndex + range)) {
						String[] lc =  {sentence[i], sentence[i+2]};
						localCollocations.add(lc);
					}
			}
			
		}
		
		return localCollocations;
	}

	
	/**
	 * @Algorithm: SST
	 * 
	 * The following methods serve to extract the features for the algorithm SST.
	 */
	
	
	
	
	
}