samoa-api/src/main/java/org/apache/samoa/learners/classifiers/ensemble/Boosting.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.samoa.learners.classifiers.ensemble;

import com.google.common.collect.ImmutableSet;

import java.util.Set;

import org.apache.samoa.core.Processor;
import org.apache.samoa.instances.Instances;
import org.apache.samoa.learners.ClassificationLearner;
import org.apache.samoa.learners.Learner;
import org.apache.samoa.learners.classifiers.SingleClassifier;
import org.apache.samoa.topology.Stream;
import org.apache.samoa.topology.TopologyBuilder;

import com.github.javacliparser.ClassOption;
import com.github.javacliparser.Configurable;
import com.github.javacliparser.IntOption;

/**
 * The Bagging Classifier by Oza and Russell.
 */
public class Boosting implements ClassificationLearner, Configurable {

  /** The Constant serialVersionUID. */
  private static final long serialVersionUID = -2971850264864952099L;

  /** The base learner option. */
  public ClassOption baseLearnerOption = new ClassOption("baseLearner", 'l',
      "Classifier to train.", Learner.class, SingleClassifier.class.getName());

  /** The ensemble size option. */
  public IntOption ensembleSizeOption = new IntOption("ensembleSize", 's',
      "The number of models in the bag.", 10, 1, Integer.MAX_VALUE);

  /** The distributor processor. */
  private BoostingDistributorProcessor distributorP;

  /** The result stream. */
  protected Stream resultStream;

  /** The dataset. */
  private Instances dataset;

  protected Learner classifier;

  protected int parallelism;

  /**
   * Sets the layout.
   */
  protected void setLayout() {

    int sizeEnsemble = this.ensembleSizeOption.getValue();

    distributorP = new BoostingDistributorProcessor();
    distributorP.setEnsembleSize(sizeEnsemble);
    this.builder.addProcessor(distributorP, 1);

    // instantiate classifier
    classifier = this.baseLearnerOption.getValue();
    classifier.init(builder, this.dataset, sizeEnsemble);

    BoostingPredictionCombinerProcessor predictionCombinerP = new BoostingPredictionCombinerProcessor();
    predictionCombinerP.setEnsembleSize(sizeEnsemble);
    this.builder.addProcessor(predictionCombinerP, 1);

    // Streams
    resultStream = this.builder.createStream(predictionCombinerP);
    predictionCombinerP.setOutputStream(resultStream);

    for (Stream subResultStream : classifier.getResultStreams()) {
      this.builder.connectInputKeyStream(subResultStream, predictionCombinerP);
    }

    /* The testing stream. */
    Stream testingStream = this.builder.createStream(distributorP);
    this.builder.connectInputKeyStream(testingStream, classifier.getInputProcessor());

    /* The prediction stream. */
    Stream predictionStream = this.builder.createStream(distributorP);
    this.builder.connectInputKeyStream(predictionStream, classifier.getInputProcessor());

    // Addition to Bagging: stream to train
    /* The training stream. */
    Stream trainingStream = this.builder.createStream(predictionCombinerP);
    predictionCombinerP.setTrainingStream(trainingStream);
    this.builder.connectInputKeyStream(trainingStream, classifier.getInputProcessor());

  }

  /** The builder. */
  private TopologyBuilder builder;

  /*
   * (non-Javadoc)
   * 
   * @see samoa.classifiers.Classifier#init(samoa.engines.Engine,
   * samoa.core.Stream, weka.core.Instances)
   */

  @Override
  public void init(TopologyBuilder builder, Instances dataset, int parallelism) {
    this.builder = builder;
    this.dataset = dataset;
    this.parallelism = parallelism;
    this.setLayout();
  }

  @Override
  public Processor getInputProcessor() {
    return distributorP;
  }

  /*
   * (non-Javadoc)
   * 
   * @see samoa.learners.Learner#getResultStreams()
   */
  @Override
  public Set<Stream> getResultStreams() {
    return ImmutableSet.of(this.resultStream);
  }
}