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126 lines
4.2 KiB
Plaintext
126 lines
4.2 KiB
Plaintext
/** \ingroup core
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* \class QgsDateTimeStatisticalSummary
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* \brief Calculator for summary statistics and aggregates for a list of datetimes.
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*
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* Statistics are calculated by calling @link calculate @endlink and passing a list of datetimes. The
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* individual statistics can then be retrieved using the associated methods. Note that not all statistics
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* are calculated by default. Statistics which require slower computations are only calculated by
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* specifying the statistic in the constructor or via @link setStatistics @endlink.
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*
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* \note Added in version 2.16
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*/
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class QgsDateTimeStatisticalSummary
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{
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%TypeHeaderCode
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#include <qgsdatetimestatisticalsummary.h>
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%End
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public:
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//! Enumeration of flags that specify statistics to be calculated
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enum Statistic
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{
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Count, //!< Count
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CountDistinct, //!< Number of distinct datetime values
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CountMissing, //!< Number of missing (null) values
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Min, //!< Minimum (earliest) datetime value
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Max, //!< Maximum (latest) datetime value
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Range, //!< Interval between earliest and latest datetime value
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All, //! All statistics
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};
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typedef QFlags<QgsDateTimeStatisticalSummary::Statistic> Statistics;
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/** Constructor for QgsDateTimeStatisticalSummary
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* @param stats flags for statistics to calculate
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*/
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QgsDateTimeStatisticalSummary( QgsDateTimeStatisticalSummary::Statistics stats = All );
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/** Returns flags which specify which statistics will be calculated. Some statistics
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* are always calculated (e.g., count).
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* @see setStatistics
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*/
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Statistics statistics() const;
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/** Sets flags which specify which statistics will be calculated. Some statistics
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* are always calculated (e.g., count).
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* @param stats flags for statistics to calculate
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* @see statistics
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*/
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void setStatistics( Statistics stats );
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/** Resets the calculated values
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*/
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void reset();
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/** Calculates summary statistics for a list of variants. Any non-datetime variants will be
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* ignored.
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* @param values list of variants
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* @see addValue()
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*/
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void calculate( const QVariantList& values );
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/** Adds a single datetime to the statistics calculation. Calling this method
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* allows datetimes to be added to the calculation one at a time. For large
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* quantities of dates this may be more efficient then first adding all the
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* variants to a list and calling calculate().
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* @param value datetime to add. Any non-datetime variants will be ignored.
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* @note call reset() before adding the first datetime using this method
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* to clear the results from any previous calculations
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* @note finalize() must be called after adding the final value and before
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* retrieving calculated statistics.
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* @see calculate()
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* @see finalize()
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*/
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void addValue( const QVariant& value );
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/** Must be called after adding all datetimes with addValue() and before retrieving
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* any calculated datetime statistics.
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* @see addValue()
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*/
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void finalize();
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/** Returns the value of a specified statistic
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* @param stat statistic to return
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* @returns calculated value of statistic
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*/
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QVariant statistic( Statistic stat ) const;
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/** Returns the calculated count of values.
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*/
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int count() const;
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/** Returns the number of distinct datetime values.
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*/
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int countDistinct() const;
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/** Returns the set of distinct datetime values.
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*/
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QSet< QDateTime > distinctValues() const;
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/** Returns the number of missing (null) datetime values.
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*/
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int countMissing() const;
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/** Returns the minimum (earliest) non-null datetime value.
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*/
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QDateTime min() const;
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/** Returns the maximum (latest) non-null datetime value.
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*/
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QDateTime max() const;
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/** Returns the range (interval between earliest and latest non-null datetime values).
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*/
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QgsInterval range() const;
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/** Returns the friendly display name for a statistic
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* @param statistic statistic to return name for
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*/
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static QString displayName( Statistic statistic );
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};
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QFlags<QgsDateTimeStatisticalSummary::Statistic> operator|(QgsDateTimeStatisticalSummary::Statistic f1, QFlags<QgsDateTimeStatisticalSummary::Statistic> f2);
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