org.kalypso.ogc.sensor.timeseries.TimestampGuesser.java Source code

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Here is the source code for org.kalypso.ogc.sensor.timeseries.TimestampGuesser.java

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/*----------------    FILE HEADER KALYPSO ------------------------------------------
 *
 *  This file is part of kalypso.
 *  Copyright (C) 2004 by:
 *
 *  Technical University Hamburg-Harburg (TUHH)
 *  Institute of River and coastal engineering
 *  Denickestrae 22
 *  21073 Hamburg, Germany
 *  http://www.tuhh.de/wb
 *
 *  and
 *
 *  Bjoernsen Consulting Engineers (BCE)
 *  Maria Trost 3
 *  56070 Koblenz, Germany
 *  http://www.bjoernsen.de
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Contact:
 *
 *  E-Mail:
 *  belger@bjoernsen.de
 *  schlienger@bjoernsen.de
 *  v.doemming@tuhh.de
 *
 *  ---------------------------------------------------------------------------*/
package org.kalypso.ogc.sensor.timeseries;

import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

import org.joda.time.LocalTime;
import org.kalypso.contribs.java.util.CalendarUtilities;
import org.kalypso.ogc.sensor.IAxis;
import org.kalypso.ogc.sensor.ITupleModel;
import org.kalypso.ogc.sensor.SensorException;

import com.google.common.collect.HashMultiset;
import com.google.common.collect.Multiset;

/**
 * Helper class that guesses the timestamp from a given timeseries.<br/>
 * REMARK: This class priorizes times in Winter, and only tests summer times, if no winter times are available at all.
 * All/Most of the old projects have problematic timeseries.
 * 
 * @author Holger Albert
 */
public class TimestampGuesser {
    /**
     * The tuple model of a timeseries.
     */
    private final ITupleModel m_timeseries;

    /**
     * The number of test steps. -1, if the entire timeseries should be tested.
     */
    private final int m_testSteps;

    /**
     * The constructor.
     * 
     * @param timeseries
     *          The tuple model of a timeseries.
     * @param testSteps
     *          The number of test steps. -1, if the entire timeseries should be tested.
     */
    public TimestampGuesser(final ITupleModel timeseries, final int testSteps) {
        m_timeseries = timeseries;
        m_testSteps = testSteps;
    }

    /**
     * This function guesses the timestamp.
     * 
     * @return The timestamp in UTC.
     */
    public LocalTime execute() throws SensorException {
        /* Used to determine the number of equal timestamps. */
        final Multiset<LocalTime> timestampsDSTWinter = HashMultiset.create();
        final Multiset<LocalTime> timestampsDSTSummer = HashMultiset.create();

        /* Get the number of test steps. */
        final int testSteps = getTestSteps();

        /* Find the date axis. */
        final IAxis dateAxis = AxisUtils.findDateAxis(m_timeseries.getAxes());
        if (dateAxis == null)
            throw new IllegalArgumentException("Argument mus tbe a timeseries"); //$NON-NLS-1$

        /* Collect all timestamps. */
        for (int i = 0; i < testSteps; i++) {
            /* REMARK: We need UTC here. */
            final Date date = (Date) m_timeseries.get(i, dateAxis);
            final Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC")); //$NON-NLS-1$
            calendar.setTime(date);

            /* Differ between daylight saving winter and summer times. */
            /* Old zml daylight saving summer times are possible broken! */
            final boolean dstWinterTime = CalendarUtilities.isDSTWinterTime(date);

            /* REMARK: The ISO Chronolgy used will have the UTC timezone set. */
            /* REMARK: See the source code of the constructor. */
            final LocalTime timestamp = new LocalTime(calendar.get(Calendar.HOUR_OF_DAY),
                    calendar.get(Calendar.MINUTE));
            if (dstWinterTime)
                timestampsDSTWinter.add(timestamp);
            else
                timestampsDSTSummer.add(timestamp);
        }

        /* We want to use the one, with the most occurences. */
        final LocalTime timestamp = doGuessTimestamp(timestampsDSTWinter);
        if (timestamp != null)
            return timestamp;

        return doGuessTimestamp(timestampsDSTSummer);
    }

    /**
     * This function returns the timestamp with the most occurances.
     * 
     * @param timestamps
     *          The timestamps
     * @return The timestamp with the most occurances.
     */
    private LocalTime doGuessTimestamp(final Multiset<LocalTime> timestamps) {
        LocalTime foundTimestamp = null;
        int maxCount = 0;
        for (final LocalTime timestamp : timestamps) {
            final int count = timestamps.count(timestamp);
            if (count > maxCount) {
                foundTimestamp = timestamp;
                maxCount = count;
            }
        }

        return foundTimestamp;
    }

    /**
     * This function returns the number of test steps.
     * 
     * @return The size of the timeseries if no number of test steps was provided in the constructor. Otherwise it returns
     *         the lower number of either the size of the timeseries or the provided number of test steps.
     */
    private int getTestSteps() throws SensorException {
        /* Get the size of the timeseries. */
        final int size = m_timeseries.size();
        if (m_testSteps == -1)
            return size;

        /* Prevent that the timeseries is smaller then number of test steps. */
        return Math.min(size, m_testSteps);
    }
}