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/** \ingroup core
* \class QgsStatisticalSummary
* \brief Calculator for summary statistics for a list of doubles.
*
* Statistics are calculated by calling @link calculate @endlink and passing a list of doubles. The
* individual statistics can then be retrieved using the associated methods. Note that not all statistics
* are calculated by default. Statistics which require slower computations are only calculated by
* specifying the statistic in the constructor or via @link setStatistics @endlink.
*
* \note Added in version 2.9
*/
class QgsStatisticalSummary
{
%TypeHeaderCode
#include <qgsstatisticalsummary.h>
%End
public:
//! Enumeration of flags that specify statistics to be calculated
enum Statistic
{
Count, //!< Count
CountMissing, //!< Number of missing (null) values
Sum, //!< Sum of values
Mean, //!< Mean of values
Median, //!< Median of values
StDev, //!< Standard deviation of values
StDevSample, //!< Sample standard deviation of values
Min, //!< Min of values
Max, //!< Max of values
Range, //!< Range of values (max - min)
Minority, //!< Minority of values
Majority, //!< Majority of values
Variety, //!< Variety (count of distinct) values
FirstQuartile, //!< First quartile
ThirdQuartile, //!< Third quartile
InterQuartileRange, //!< Inter quartile range (IQR)
All
};
typedef QFlags<QgsStatisticalSummary::Statistic> Statistics;
/** Constructor for QgsStatisticalSummary
* @param stats flags for statistics to calculate
*/
QgsStatisticalSummary( const QgsStatisticalSummary::Statistics& stats = QgsStatisticalSummary::All );
virtual ~QgsStatisticalSummary();
/** Returns flags which specify which statistics will be calculated. Some statistics
* are always calculated (eg sum, min and max).
* @see setStatistics
*/
QgsStatisticalSummary::Statistics statistics() const;
/** Sets flags which specify which statistics will be calculated. Some statistics
* are always calculated (eg sum, min and max).
* @param stats flags for statistics to calculate
* @see statistics
*/
void setStatistics( const QgsStatisticalSummary::Statistics& stats );
/** Resets the calculated values
*/
void reset();
/** Calculates summary statistics for a list of values
* @param values list of doubles
*/
void calculate( const QList<double>& values );
/** Adds a single value to the statistics calculation. Calling this method
* allows values to be added to the calculation one at a time. For large
* quantities of values this may be more efficient then first adding all the
* values to a list and calling calculate().
* @param value value to add
* @note call reset() before adding the first value using this method
* to clear the results from any previous calculations
* @note finalize() must be called after adding the final value and before
* retrieving calculated statistics.
* @see calculate()
* @see addVariant()
* @see finalize()
* @note added in QGIS 2.16
*/
void addValue( double value );
/** Adds a single value to the statistics calculation. Calling this method
* allows values to be added to the calculation one at a time. For large
* quantities of values this may be more efficient then first adding all the
* values to a list and calling calculate().
* @param value variant containing to add. Non-numeric values are treated as null.
* @note call reset() before adding the first value using this method
* to clear the results from any previous calculations
* @note finalize() must be called after adding the final value and before
* retrieving calculated statistics.
* @see addValue()
* @see calculate()
* @see finalize()
* @note added in QGIS 2.16
*/
void addVariant( const QVariant& value );
/** Must be called after adding all values with addValues() and before retrieving
* any calculated statistics.
* @see addValue()
* @see addVariant()
* @note added in QGIS 2.16
*/
void finalize();
/** Returns the value of a specified statistic
* @param stat statistic to return
* @returns calculated value of statistic
*/
double statistic( Statistic stat ) const;
/** Returns calculated count of values
*/
int count() const;
/** Returns the number of missing (null) values
* @note added in QGIS 2.16
*/
int countMissing() const;
/** Returns calculated sum of values
*/
double sum() const;
/** Returns calculated mean of values
*/
double mean() const;
/** Returns calculated median of values. This is only calculated if Statistic::Median has
* been specified in the constructor or via setStatistics.
*/
double median() const;
/** Returns calculated minimum from values.
*/
double min() const;
/** Returns calculated maximum from values.
*/
double max() const;
/** Returns calculated range (difference between maximum and minimum values).
*/
double range() const;
/** Returns population standard deviation. This is only calculated if Statistic::StDev has
* been specified in the constructor or via setStatistics.
* @see sampleStDev
*/
double stDev() const;
/** Returns sample standard deviation. This is only calculated if Statistic::StDev has
* been specified in the constructor or via setStatistics.
* @see stDev
*/
double sampleStDev() const;
/** Returns variety of values. The variety is the count of unique values from the list.
* This is only calculated if Statistic::Variety has been specified in the constructor
* or via setStatistics.
*/
int variety() const;
/** Returns minority of values. The minority is the value with least occurances in the list
* This is only calculated if Statistic::Minority has been specified in the constructor
* or via setStatistics.
* @see majority
*/
double minority() const;
/** Returns majority of values. The majority is the value with most occurances in the list
* This is only calculated if Statistic::Majority has been specified in the constructor
* or via setStatistics.
* @see minority
*/
double majority() const;
/** Returns the first quartile of the values. The quartile is calculated using the
* "Tukey's hinges" method.
* @see thirdQuartile
* @see interQuartileRange
*/
double firstQuartile() const;
/** Returns the third quartile of the values. The quartile is calculated using the
* "Tukey's hinges" method.
* @see firstQuartile
* @see interQuartileRange
*/
double thirdQuartile() const;
/** Returns the inter quartile range of the values. The quartiles are calculated using the
* "Tukey's hinges" method.
* @see firstQuartile
* @see thirdQuartile
*/
double interQuartileRange() const;
/** Returns the friendly display name for a statistic
* @param statistic statistic to return name for
*/
static QString displayName( Statistic statistic );
};
QFlags<QgsStatisticalSummary::Statistic> operator|(QgsStatisticalSummary::Statistic f1, QFlags<QgsStatisticalSummary::Statistic> f2);
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