opennlp-similarity/src/main/java/opennlp/tools/textsimilarity/POSManager.java

/*
 * 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.textsimilarity;

public class POSManager {
  public POSManager() {

  }

  public String similarPOS(String pos1, String pos2) {
    if ((pos1.startsWith("NN") && pos2.equals("NP") || pos2.startsWith("NN")
        && pos1.equals("NP"))) {
      return "NN";
    }
    if ((pos1.startsWith("NN") && pos2.equals("VBG") || pos2.startsWith("VBG")
        && pos1.equals("NN"))) {
      return "NN";
    }

    if ((pos1.startsWith("NN") && pos2.equals("ADJP") || pos2.startsWith("NN")
        && pos1.equals("ADJP"))) {
      return "NN";
    }
    if ((pos1.equals("IN") && pos2.equals("TO") || pos1.equals("TO")
        && pos2.equals("IN"))) {
      return "IN";
    }
    // VBx vs VBx = VB (does not matter which form for verb)
    if (pos1.startsWith("VB") && pos2.startsWith("VB")) {
      return "VB";
    }

    // ABx vs ABy always gives AB
    if (pos1.equalsIgnoreCase(pos2)) {
      return pos1;
    }
    if (pos1.length() > 2) {
      pos1 = pos1.substring(0, 2);
    }

    if (pos2.length() > 2) {
      pos2 = pos2.substring(0, 2);
    }
    if (pos1.equalsIgnoreCase(pos2)) {
      return pos1 + "*";
    }
    return null;
  }

}