TTFReferenceFeatureFileBuilder.java

package uk.ac.shef.dcs.jate.feature;

import org.apache.commons.lang.exception.ExceptionUtils;
import uk.ac.shef.dcs.jate.JATEException;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import org.apache.log4j.Logger;

/**
 * A specific type of feature builder that builds an instance of
 * FeatureRefCorpusTermFrequency. This is a dummy class which reads the data
 * from a text file which stores information as: <br>
 * [freq_in_corpus] [term]
 *
 * @author <a href="mailto:ziqi.zhang@sheffield.ac.uk">Ziqi Zhang</a>
 */

public class TTFReferenceFeatureFileBuilder extends AbstractFeatureBuilder {

	protected final Logger LOG = Logger.getLogger(TTFReferenceFeatureFileBuilder.class.getName());

	private final String _refStatsPath;

	/**
	 * Default constructor
	 *
	 * @param refStatsPath
	 *            file path to the reference corpus statistics file. The file
	 *            should store one term on a line, and in the format of: <br>
	 *            [freq_in_ref_corpus] [term] <br>
	 *            Any terms with frequency < 2 will be ignored.
	 */
	public TTFReferenceFeatureFileBuilder(String refStatsPath) {
		super(null, null);
		_refStatsPath = refStatsPath;
	}

	/**
	 * Dummy method which does nothing with the GlobalIndexMem instance but load
	 * statistics and creates and instance of FeatureRefCorpusTermFrequency from
	 * the file specified in the constructor
	 *
	 * @return uk.ac.shef.dcs.jate.feature.FrequencyTermBased
	 * @throws uk.ac.shef.dcs.jate.JATEException
	 */
	public FrequencyTermBased build() throws JATEException {
		FrequencyTermBased feature = new FrequencyTermBased();

		try {
			final BufferedReader reader = new BufferedReader(new FileReader(_refStatsPath));
			try {
				String line;
				while ((line = reader.readLine()) != null) {
					line = line.trim();
					String[] elements = line.split("\\s+");
					if (Integer.valueOf(elements[0]) < 2)
						continue;
					feature.increment(elements[1].trim(), Integer.valueOf(elements[0]));
				}
			} finally {
				reader.close();
			}

		} catch (IOException e) {
			StringBuilder sb = new StringBuilder("Failed to build features!");
			sb.append("\n").append(ExceptionUtils.getFullStackTrace(e));
			throw new JATEException(sb.toString());
		}
		return feature;
	}
}