AbstractChangeDetector.java

package com.yahoo.labs.samoa.moa.classifiers.core.driftdetection;

/*
 * #%L
 * SAMOA
 * %%
 *    Copyright (C) 2013 University of Waikato, Hamilton, New Zealand
 * %%
 * 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.
 * #L%
 */

import com.yahoo.labs.samoa.moa.options.AbstractOptionHandler;

/**
 * Abstract Change Detector. All change detectors in MOA extend this class.
 *
 * @author Albert Bifet (abifet at cs dot waikato dot ac dot nz)
 * @version $Revision: 7 $
 */
public abstract class AbstractChangeDetector extends AbstractOptionHandler
        implements ChangeDetector {



    /**
     * Change was detected
     */
    protected boolean isChangeDetected;

    /**
     * Warning Zone: after a warning and before a change 
     */
    protected boolean isWarningZone;

    /**
     * Prediction for the next value based in previous seen values
     */
    protected double estimation;

    /**
     * Delay in detecting change
     */
    protected double delay;

    /**
     * Resets this change detector. It must be similar to starting a new change
     * detector from scratch.
     *
     */
    public void resetLearning() {
        this.isChangeDetected = false;
        this.isWarningZone = false;
        this.estimation = 0.0;
        this.delay = 0.0;
    }

    /**
     * Adding a numeric value to the change detector<br><br>
     *
     * The output of the change detector is modified after the insertion of a
     * new item inside.
     *
     * @param inputValue the number to insert into the change detector
     */
    public abstract void input(double inputValue);

    /**
     * Gets whether there is change detected.
     *
     * @return true if there is change
     */
    public boolean getChange() {
        return this.isChangeDetected;
    }

    /**
     * Gets whether the change detector is in the warning zone, after a warning
     * alert and before a change alert.
     *
     * @return true if the change detector is in the warning zone
     */
    public boolean getWarningZone() {
        return this.isWarningZone;
    }

    /**
     * Gets the prediction of next values.
     *
     * @return a prediction of the next value
     */
    public double getEstimation() {
        return this.estimation;
    }

    /**
     * Gets the length of the delay in the change detected.
     *
     * @return he length of the delay in the change detected
     */
    public double getDelay() {
        return this.delay;
    }

    /**
     * Gets the output state of the change detection.
     *
     * @return an array with the number of change detections, number of
     * warnings, delay, and estimation.
     */
    public double[] getOutput() {
        return new double[]{this.isChangeDetected ? 1 : 0, this.isWarningZone ? 1 : 0, this.delay, this.estimation};
    }

    /**
     * Returns a string representation of the model.
     *
     * @param sb	the stringbuilder to add the description
     * @param indent	the number of characters to indent
     */
    @Override
    public abstract void getDescription(StringBuilder sb, int indent);

    /**
     * Produces a copy of this change detector method
     *
     * @return the copy of this change detector method
     */
    @Override
    public ChangeDetector copy() {
        return (ChangeDetector) super.copy();
    }
}