eus.ixa.ixa.pipe.nerc.formats.CoNLL02Format Maven / Gradle / Ivy

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ixa pipes sequence labeler (ixa2.si.ehu.es/ixa-pipes).
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/*
 *  Copyright 2015 Rodrigo Agerri

   Licensed 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 eus.ixa.ixa.pipe.nerc.formats;

import java.io.IOException;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

import opennlp.tools.namefind.NameSample;
import opennlp.tools.util.InputStreamFactory;
import opennlp.tools.util.InvalidFormatException;
import opennlp.tools.util.ObjectStream;
import opennlp.tools.util.PlainTextByLineStream;
import opennlp.tools.util.Span;
import opennlp.tools.util.StringUtil;

/**
 * 2 fields CoNLL 2002 tabulated format: word\tabclass\n B- start chunk I-
 * inside chunk O- outside chunk.
 * 
 * @author ragerri
 * @version 2015-02-24
 * 
 */
public class CoNLL02Format implements ObjectStream {

  /**
   * The stream.
   */
  private final ObjectStream lineStream;
  /**
   * Whether the adaptive features are to be reset or not.
   */
  private String clearFeatures;

  /**
   * Construct a Name Stream from a language and a {@code ObjectStream}.
   * 
   * @param clearFeatures
   *          reset the adaptive features
   * @param lineStream
   *          the stream
   */
  public CoNLL02Format(String clearFeatures, ObjectStream lineStream) {
    this.clearFeatures = clearFeatures;
    this.lineStream = lineStream;
  }

  /**
   * Construct a Name Stream from a language and an input stream.
   * 
   * @param clearFeatures
   *          reset the adaptive features
   * @param in
   *          an input stream to read data
   * @throws IOException
   *           the input stream exception
   */
  public CoNLL02Format(String clearFeatures, InputStreamFactory in)
      throws IOException {
    this.clearFeatures = clearFeatures;
    try {
      this.lineStream = new PlainTextByLineStream(in, "UTF-8");
      System.setOut(new PrintStream(System.out, true, "UTF-8"));
    } catch (UnsupportedEncodingException e) {
      // UTF-8 is available on all JVMs, will never happen
      throw new IllegalStateException(e);
    }
  }

  public NameSample read() throws IOException {

    List tokens = new ArrayList();
    List neTypes = new ArrayList();

    boolean isClearAdaptiveData = false;
    // Empty line indicates end of sentence
    String line;
    while ((line = lineStream.read()) != null && !StringUtil.isEmpty(line)) {
      //clear adaptive data if document mark appears following
      //CoNLL03 conventions
      if (clearFeatures.equalsIgnoreCase("docstart") 
          && line.startsWith("-DOCSTART-")) {
        isClearAdaptiveData = true;
        String emptyLine = lineStream.read();
        if (!StringUtil.isEmpty(emptyLine))
          throw new IOException("Empty line after -DOCSTART- not empty: '" + emptyLine +"'!");
        continue;
      }
      String fields[] = line.split("\t");
      if (fields.length == 2) {
        tokens.add(fields[0]);
        neTypes.add(fields[1]);
      } else {
        throw new IOException(
            "Expected two fields per line in training data, got "
                + fields.length + " for line '" + line + "'!");
      }
    }
    // check if we need to clear features every sentence
    if (clearFeatures.equalsIgnoreCase("yes")) {
      isClearAdaptiveData = true;
    }
    if (tokens.size() > 0) {
      // convert name tags into spans
      List names = new ArrayList();
      int beginIndex = -1;
      int endIndex = -1;
      for (int i = 0; i < neTypes.size(); i++) {
        String neTag = neTypes.get(i);
        if (neTag.startsWith("B-")) {
          if (beginIndex != -1) {
            names.add(extract(beginIndex, endIndex, neTypes.get(beginIndex)));
            beginIndex = -1;
            endIndex = -1;
          }
          beginIndex = i;
          endIndex = i + 1;
        } else if (neTag.startsWith("I-")) {
          endIndex++;
        } else if (neTag.equals("O")) {
          if (beginIndex != -1) {
            names.add(extract(beginIndex, endIndex, neTypes.get(beginIndex)));
            beginIndex = -1;
            endIndex = -1;
          }
        } else {
          throw new IOException("Invalid tag: " + neTag);
        }
      }
      // if one span remains, create it here
      if (beginIndex != -1)
        names.add(extract(beginIndex, endIndex, neTypes.get(beginIndex)));

      return new NameSample(tokens.toArray(new String[tokens.size()]),
          names.toArray(new Span[names.size()]), isClearAdaptiveData);
    } else if (line != null) {
      // Just filter out empty events, if two lines in a row are empty
      return read();
    } else {
      // source stream is not returning anymore lines
      return null;
    }
  }

  static final Span extract(int begin, int end, String beginTag)
      throws InvalidFormatException {

    String type = beginTag.substring(2);
    return new Span(begin, end, type);
  }

  public void reset() throws IOException, UnsupportedOperationException {
    lineStream.reset();
  }

  public void close() throws IOException {
    lineStream.close();
  }
}