kieker.tools.opad.timeseries.forecast.mean.MeanForecasterJava.java Source code

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Here is the source code for kieker.tools.opad.timeseries.forecast.mean.MeanForecasterJava.java

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/***************************************************************************
 * Copyright 2015 Kieker Project (http://kieker-monitoring.net)
 *
 * 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 kieker.tools.opad.timeseries.forecast.mean;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.math3.stat.StatUtils;

import kieker.tools.opad.timeseries.ForecastMethod;
import kieker.tools.opad.timeseries.ITimeSeries;
import kieker.tools.opad.timeseries.forecast.AbstractForecaster;
import kieker.tools.opad.timeseries.forecast.ForecastResult;
import kieker.tools.opad.timeseries.forecast.IForecastResult;

/**
 * A Java-based time series forecaster which computes a forecast based on the mean value of the historic values.
 *
 * @author Andre van Hoorn
 * @since 1.10
 */
public class MeanForecasterJava extends AbstractForecaster<Double> {

    /**
     *
     * @param historyTimeseries
     *            TimeSeries
     */
    public MeanForecasterJava(final ITimeSeries<Double> historyTimeseries) {
        super(historyTimeseries);
    }

    /**
     * @param numForecastSteps
     *            number of values the forecaster is going to forecast
     *
     * @return Forecast Result
     */
    @Override
    public IForecastResult forecast(final int numForecastSteps) {
        final ITimeSeries<Double> history = this.getTsOriginal();
        final ITimeSeries<Double> tsFC = this.prepareForecastTS();

        final List<Double> allHistory = new ArrayList<Double>(history.getValues());
        final Double[] histValuesNotNull = MeanForecasterJava.removeNullValues(allHistory);
        final double mean = StatUtils.mean(ArrayUtils.toPrimitive(histValuesNotNull));
        final Double[] forecastValues = new Double[numForecastSteps];
        Arrays.fill(forecastValues, mean);

        tsFC.appendAll(forecastValues);
        return new ForecastResult(tsFC, this.getTsOriginal(), ForecastMethod.MEAN);
    }

    /**
     *
     * @param allHistory
     *            List there null values should deltet in this function
     * @return List/Array with no NullValues
     */
    public static Double[] removeNullValues(final List<Double> allHistory) {
        final List<Double> newList = new ArrayList<Double>();

        for (final Object obj : allHistory) {
            if ((null != obj) && (obj instanceof Double) && !Double.isNaN((Double) obj)) {
                newList.add((Double) obj);
            }
        }
        return newList.toArray(new Double[newList.size()]);
    }

    @Override
    protected boolean supportsConfidence() {
        // Does not support confidence;
        return false;
    }
}