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       1                 :            : /***************************************************************************
       2                 :            :   qgsdatetimestatisticalsummary.h
       3                 :            :   -------------------------------
       4                 :            :   Date                 : May 2016
       5                 :            :   Copyright            : (C) 2016 by Nyall Dawson
       6                 :            :   Email                : nyall dot dawson at gmail dot com
       7                 :            :  ***************************************************************************
       8                 :            :  *                                                                         *
       9                 :            :  *   This program is free software; you can redistribute it and/or modify  *
      10                 :            :  *   it under the terms of the GNU General Public License as published by  *
      11                 :            :  *   the Free Software Foundation; either version 2 of the License, or     *
      12                 :            :  *   (at your option) any later version.                                   *
      13                 :            :  *                                                                         *
      14                 :            :  ***************************************************************************/
      15                 :            : 
      16                 :            : #ifndef QGSDATETIMESTATISTICALSUMMARY_H
      17                 :            : #define QGSDATETIMESTATISTICALSUMMARY_H
      18                 :            : 
      19                 :            : #include "qgis_core.h"
      20                 :            : #include "qgis_sip.h"
      21                 :            : #include "qgsinterval.h"
      22                 :            : #include <QSet>
      23                 :            : #include <QDateTime>
      24                 :            : #include <QVariantList>
      25                 :            : 
      26                 :            : /***************************************************************************
      27                 :            :  * This class is considered CRITICAL and any change MUST be accompanied with
      28                 :            :  * full unit tests in test_qgsdatetimestatisticalsummary.py.
      29                 :            :  * See details in QEP #17
      30                 :            :  ****************************************************************************/
      31                 :            : 
      32                 :            : /**
      33                 :            :  * \ingroup core
      34                 :            :  * \class QgsDateTimeStatisticalSummary
      35                 :            :  * \brief Calculator for summary statistics and aggregates for a list of datetimes.
      36                 :            :  *
      37                 :            :  * Statistics are calculated by calling calculate() and passing a list of datetimes. The
      38                 :            :  * individual statistics can then be retrieved using the associated methods. Note that not all statistics
      39                 :            :  * are calculated by default. Statistics which require slower computations are only calculated by
      40                 :            :  * specifying the statistic in the constructor or via setStatistics().
      41                 :            :  *
      42                 :            :  * \since QGIS 2.16
      43                 :            :  */
      44                 :            : 
      45                 :          0 : class CORE_EXPORT QgsDateTimeStatisticalSummary
      46                 :            : {
      47                 :            :   public:
      48                 :            : 
      49                 :            :     //! Enumeration of flags that specify statistics to be calculated
      50                 :            :     enum Statistic
      51                 :            :     {
      52                 :            :       Count = 1,  //!< Count
      53                 :            :       CountDistinct = 2,  //!< Number of distinct datetime values
      54                 :            :       CountMissing = 4,  //!< Number of missing (null) values
      55                 :            :       Min = 8, //!< Minimum (earliest) datetime value
      56                 :            :       Max = 16, //!< Maximum (latest) datetime value
      57                 :            :       Range = 32, //!< Interval between earliest and latest datetime value
      58                 :            :       All = Count | CountDistinct | CountMissing | Min | Max | Range, //!< All statistics
      59                 :            :     };
      60                 :            :     Q_DECLARE_FLAGS( Statistics, Statistic )
      61                 :            : 
      62                 :            :     /**
      63                 :            :      * Constructor for QgsDateTimeStatisticalSummary
      64                 :            :      * \param stats flags for statistics to calculate
      65                 :            :      */
      66                 :            :     QgsDateTimeStatisticalSummary( QgsDateTimeStatisticalSummary::Statistics stats = All );
      67                 :            : 
      68                 :            :     /**
      69                 :            :      * Returns flags which specify which statistics will be calculated. Some statistics
      70                 :            :      * are always calculated (e.g., count).
      71                 :            :      * \see setStatistics
      72                 :            :      */
      73                 :            :     Statistics statistics() const { return mStatistics; }
      74                 :            : 
      75                 :            :     /**
      76                 :            :      * Sets flags which specify which statistics will be calculated. Some statistics
      77                 :            :      * are always calculated (e.g., count).
      78                 :            :      * \param stats flags for statistics to calculate
      79                 :            :      * \see statistics
      80                 :            :      */
      81                 :            :     void setStatistics( Statistics stats ) { mStatistics = stats; }
      82                 :            : 
      83                 :            :     /**
      84                 :            :      * Resets the calculated values
      85                 :            :      */
      86                 :            :     void reset();
      87                 :            : 
      88                 :            :     /**
      89                 :            :      * Calculates summary statistics for a list of variants. Any non-datetime variants will be
      90                 :            :      * ignored.
      91                 :            :      * \param values list of variants
      92                 :            :      * \see addValue()
      93                 :            :      */
      94                 :            :     void calculate( const QVariantList &values );
      95                 :            : 
      96                 :            :     /**
      97                 :            :      * Adds a single datetime to the statistics calculation. Calling this method
      98                 :            :      * allows datetimes to be added to the calculation one at a time. For large
      99                 :            :      * quantities of dates this may be more efficient then first adding all the
     100                 :            :      * variants to a list and calling calculate().
     101                 :            :      * \param value datetime to add. Any non-datetime variants will be ignored.
     102                 :            :      * \note call reset() before adding the first datetime using this method
     103                 :            :      * to clear the results from any previous calculations
     104                 :            :      * \note finalize() must be called after adding the final value and before
     105                 :            :      * retrieving calculated statistics.
     106                 :            :      * \see calculate()
     107                 :            :      * \see finalize()
     108                 :            :      */
     109                 :            :     void addValue( const QVariant &value );
     110                 :            : 
     111                 :            :     /**
     112                 :            :      * Must be called after adding all datetimes with addValue() and before retrieving
     113                 :            :      * any calculated datetime statistics.
     114                 :            :      * \see addValue()
     115                 :            :      */
     116                 :            :     void finalize();
     117                 :            : 
     118                 :            :     /**
     119                 :            :      * Returns the value of a specified statistic
     120                 :            :      * \param stat statistic to return
     121                 :            :      * \returns calculated value of statistic
     122                 :            :      */
     123                 :            :     QVariant statistic( QgsDateTimeStatisticalSummary::Statistic stat ) const;
     124                 :            : 
     125                 :            :     /**
     126                 :            :      * Returns the calculated count of values.
     127                 :            :      */
     128                 :            :     int count() const { return mCount; }
     129                 :            : 
     130                 :            :     /**
     131                 :            :      * Returns the number of distinct datetime values.
     132                 :            :      */
     133                 :            :     int countDistinct() const { return mValues.count(); }
     134                 :            : 
     135                 :            :     /**
     136                 :            :      * Returns the set of distinct datetime values.
     137                 :            :      */
     138                 :            :     QSet< QDateTime > distinctValues() const { return mValues; }
     139                 :            : 
     140                 :            :     /**
     141                 :            :      * Returns the number of missing (null) datetime values.
     142                 :            :      */
     143                 :            :     int countMissing() const { return mCountMissing; }
     144                 :            : 
     145                 :            :     /**
     146                 :            :      * Returns the minimum (earliest) non-null datetime value.
     147                 :            :      */
     148                 :            :     QDateTime min() const { return mMin; }
     149                 :            : 
     150                 :            :     /**
     151                 :            :      * Returns the maximum (latest) non-null datetime value.
     152                 :            :      */
     153                 :            :     QDateTime max() const { return mMax; }
     154                 :            : 
     155                 :            :     /**
     156                 :            :      * Returns the range (interval between earliest and latest non-null datetime values).
     157                 :            :      */
     158                 :            :     QgsInterval range() const { return mMax - mMin; }
     159                 :            : 
     160                 :            :     /**
     161                 :            :      * Returns the friendly display name for a statistic
     162                 :            :      * \param statistic statistic to return name for
     163                 :            :      */
     164                 :            :     static QString displayName( QgsDateTimeStatisticalSummary::Statistic statistic );
     165                 :            : 
     166                 :            :   private:
     167                 :            : 
     168                 :            :     Statistics mStatistics;
     169                 :            : 
     170                 :            :     int mCount;
     171                 :            :     QSet< QDateTime > mValues;
     172                 :            :     int mCountMissing;
     173                 :            :     QDateTime mMin;
     174                 :            :     QDateTime mMax;
     175                 :            :     bool mIsTimes;
     176                 :            : 
     177                 :            :     void testDateTime( const QDateTime &dateTime, bool isNull );
     178                 :            : };
     179                 :            : 
     180                 :            : Q_DECLARE_OPERATORS_FOR_FLAGS( QgsDateTimeStatisticalSummary::Statistics )
     181                 :            : 
     182                 :            : #endif // QGSDATETIMESTATISTICALSUMMARY_H