opennlp-ml/src/main/java/org/apache/opennlp/ml/perceptron/PerceptronModelReader.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 org.apache.opennlp.ml.perceptron;

import java.io.File;
import java.io.IOException;

import org.apache.opennlp.ml.model.AbstractModel;
import org.apache.opennlp.ml.model.AbstractModelReader;
import org.apache.opennlp.ml.model.Context;
import org.apache.opennlp.ml.model.DataReader;

/**
 * Abstract parent class for readers of Perceptron.
 *
 */
public class PerceptronModelReader extends AbstractModelReader {
  
    public PerceptronModelReader(File file) throws IOException {
      super(file);
    }
  
    public PerceptronModelReader(DataReader dataReader) {
      super(dataReader);
    }
    
    /**
     * Retrieve a model from disk. It assumes that models are saved in the
     * following sequence:
     * 
     * <br>Perceptron (model type identifier)
     * <br>1. # of parameters (int)
     * <br>2. # of outcomes (int)
     * <br>  * list of outcome names (String)
     * <br>3. # of different types of outcome patterns (int)
     * <br>   * list of (int int[])
     * <br>   [# of predicates for which outcome pattern is true] [outcome pattern]
     * <br>4. # of predicates (int)
     * <br>   * list of predicate names (String)
     *
     * <p>If you are creating a reader for a format which won't work with this
     * (perhaps a database or xml file), override this method and ignore the
     * other methods provided in this abstract class.
     *
     * @return The PerceptronModel stored in the format and location specified to
     *         this PerceptronModelReader (usually via its the constructor).
     */
    public AbstractModel constructModel() throws IOException {
      String[] outcomeLabels = getOutcomes();
      int[][] outcomePatterns = getOutcomePatterns();
      String[] predLabels = getPredicates();
      Context[] params = getParameters(outcomePatterns);
    
      return new PerceptronModel(params,
                          predLabels,
                          outcomeLabels);
    }

    public void checkModelType() throws java.io.IOException {
      String modelType = readUTF();
      if (!modelType.equals("Perceptron"))
          System.out.println("Error: attempting to load a "+modelType+
                             " model as a Perceptron model."+
                             " You should expect problems.");
    }
}