QGIS API Documentation 3.34.0-Prizren (ffbdd678812)
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QgsStatisticalSummary Class Reference

Calculator for summary statistics for a list of doubles. More...

`#include <qgsstatisticalsummary.h>`

## Public Types

enum  Statistic {
Count = 1 << 0 , CountMissing = 1 << 15 , Sum = 1 << 1 , Mean = 1 << 2 ,
Median = 1 << 3 , StDev = 1 << 4 , StDevSample = 1 << 5 , Min = 1 << 6 ,
Max = 1 << 7 , Range = 1 << 8 , Minority = 1 << 9 , Majority = 1 << 10 ,
Variety = 1 << 11 , FirstQuartile = 1 << 12 , ThirdQuartile = 1 << 13 , InterQuartileRange = 1 << 14 ,
First = 1 << 16 , Last = 1 << 17 , All = Count | CountMissing | Sum | Mean | Median | StDev | Max | Min | Range | Minority | Majority | Variety | FirstQuartile | ThirdQuartile | InterQuartileRange | First | Last
}
Enumeration of flags that specify statistics to be calculated. More...

## Public Member Functions

QgsStatisticalSummary (QgsStatisticalSummary::Statistics stats=QgsStatisticalSummary::All)
Constructor for QgsStatisticalSummary.

virtual ~QgsStatisticalSummary ()=default

Adds a single value to the statistics calculation.

Adds a single value to the statistics calculation.

void calculate (const QList< double > &values)
Calculates summary statistics for a list of values.

int count () const
Returns calculated count of values.

int countMissing () const
Returns the number of missing (null) values.

void finalize ()
Must be called after adding all values with addValues() and before retrieving any calculated statistics.

double first () const
Returns the first value obtained.

double firstQuartile () const
Returns the first quartile of the values.

double interQuartileRange () const
Returns the inter quartile range of the values.

double last () const
Returns the last value obtained.

double majority () const
Returns majority of values.

double max () const
Returns calculated maximum from values.

double mean () const
Returns calculated mean of values.

double median () const
Returns calculated median of values.

double min () const
Returns calculated minimum from values.

double minority () const
Returns minority of values.

double range () const
Returns calculated range (difference between maximum and minimum values).

void reset ()
Resets the calculated values.

double sampleStDev () const
Returns sample standard deviation.

void setStatistics (QgsStatisticalSummary::Statistics stats)
Sets flags which specify which statistics will be calculated.

double statistic (QgsStatisticalSummary::Statistic stat) const
Returns the value of a specified statistic.

Statistics statistics () const
Returns flags which specify which statistics will be calculated.

double stDev () const
Returns population standard deviation.

double sum () const
Returns calculated sum of values.

double thirdQuartile () const
Returns the third quartile of the values.

int variety () const
Returns variety of values.

## Static Public Member Functions

static QString displayName (QgsStatisticalSummary::Statistic statistic)
Returns the friendly display name for a statistic.

static QString shortName (QgsStatisticalSummary::Statistic statistic)
Returns a short, friendly display name for a statistic, suitable for use in a field name.

## Detailed Description

Calculator for summary statistics for a list of doubles.

Statistics are calculated by calling calculate() 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 setStatistics().

Since
QGIS 2.9

Definition at line 43 of file qgsstatisticalsummary.h.

## ◆ Statistic

Enumeration of flags that specify statistics to be calculated.

Enumerator
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)

First

First value (since QGIS 3.6)

Last

Last value (since QGIS 3.6)

All

Definition at line 48 of file qgsstatisticalsummary.h.

## ◆ QgsStatisticalSummary()

 QgsStatisticalSummary::QgsStatisticalSummary ( QgsStatisticalSummary::Statistics stats = `QgsStatisticalSummary::All` )

Constructor for QgsStatisticalSummary.

Parameters
 stats flags for statistics to calculate

Definition at line 28 of file qgsstatisticalsummary.cpp.

## ◆ ~QgsStatisticalSummary()

 virtual QgsStatisticalSummary::~QgsStatisticalSummary ( )
virtualdefault

## Member Function Documentation

 void QgsStatisticalSummary::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().

Parameters
Note
call reset() before adding the first value using this method to clear the results from any previous calculations
finalize() must be called after adding the final value and before retrieving calculated statistics.
calculate()
finalize()
Since
QGIS 2.16

Definition at line 85 of file qgsstatisticalsummary.cpp.

 void QgsStatisticalSummary::addVariant ( const QVariant & 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().

Parameters
 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
finalize() must be called after adding the final value and before retrieving calculated statistics.
calculate()
finalize()
Since
QGIS 2.16

Definition at line 102 of file qgsstatisticalsummary.cpp.

## ◆ calculate()

 void QgsStatisticalSummary::calculate ( const QList< double > & values )

Calculates summary statistics for a list of values.

Parameters
 values list of doubles

Definition at line 73 of file qgsstatisticalsummary.cpp.

## ◆ count()

 int QgsStatisticalSummary::count ( ) const
inline

Returns calculated count of values.

Definition at line 160 of file qgsstatisticalsummary.h.

## ◆ countMissing()

 int QgsStatisticalSummary::countMissing ( ) const
inline

Returns the number of missing (null) values.

Since
QGIS 2.16

Definition at line 166 of file qgsstatisticalsummary.h.

## ◆ displayName()

 QString QgsStatisticalSummary::displayName ( QgsStatisticalSummary::Statistic statistic )
static

Returns the friendly display name for a statistic.

shortName()

Definition at line 298 of file qgsstatisticalsummary.cpp.

## ◆ finalize()

 void QgsStatisticalSummary::finalize ( )

Must be called after adding all values with addValues() and before retrieving any calculated statistics.

Since
QGIS 2.16

Definition at line 117 of file qgsstatisticalsummary.cpp.

## ◆ first()

 double QgsStatisticalSummary::first ( ) const
inline

Returns the first value obtained.

A NaN value may be returned if no values were encountered.

last()
Since
QGIS 3.6

Definition at line 210 of file qgsstatisticalsummary.h.

## ◆ firstQuartile()

 double QgsStatisticalSummary::firstQuartile ( ) const
inline

Returns the first quartile of the values.

The quartile is calculated using the "Tukey's hinges" method. A NaN value may be returned if the first quartile cannot be calculated.

thirdQuartile
interQuartileRange

Definition at line 268 of file qgsstatisticalsummary.h.

## ◆ interQuartileRange()

 double QgsStatisticalSummary::interQuartileRange ( ) const
inline

Returns the inter quartile range of the values.

The quartiles are calculated using the "Tukey's hinges" method. A NaN value may be returned if the IQR cannot be calculated.

firstQuartile
thirdQuartile

Definition at line 286 of file qgsstatisticalsummary.h.

## ◆ last()

 double QgsStatisticalSummary::last ( ) const
inline

Returns the last value obtained.

A NaN value may be returned if no values were encountered.

first()
Since
QGIS 3.6

Definition at line 218 of file qgsstatisticalsummary.h.

## ◆ majority()

 double QgsStatisticalSummary::majority ( ) const
inline

Returns majority of values.

The majority is the value with most occurrences in the list. This is only calculated if Statistic::Majority has been specified in the constructor or via setStatistics. If multiple values match, return the first value relative to the initial values order. A NaN value may be returned if the minority cannot be calculated.

minority

Definition at line 259 of file qgsstatisticalsummary.h.

## ◆ max()

 double QgsStatisticalSummary::max ( ) const
inline

Returns calculated maximum from values.

A NaN value may be returned if the maximum cannot be calculated.

Definition at line 196 of file qgsstatisticalsummary.h.

## ◆ mean()

 double QgsStatisticalSummary::mean ( ) const
inline

Returns calculated mean of values.

A NaN value may be returned if the mean cannot be calculated.

Definition at line 177 of file qgsstatisticalsummary.h.

## ◆ median()

 double QgsStatisticalSummary::median ( ) const
inline

Returns calculated median of values.

This is only calculated if Statistic::Median has been specified in the constructor or via setStatistics. A NaN value may be returned if the median cannot be calculated.

Definition at line 184 of file qgsstatisticalsummary.h.

## ◆ min()

 double QgsStatisticalSummary::min ( ) const
inline

Returns calculated minimum from values.

A NaN value may be returned if the minimum cannot be calculated.

Definition at line 190 of file qgsstatisticalsummary.h.

## ◆ minority()

 double QgsStatisticalSummary::minority ( ) const
inline

Returns minority of values.

The minority is the value with least occurrences in the list. This is only calculated if Statistic::Minority has been specified in the constructor or via setStatistics. If multiple values match, return the first value relative to the initial values order. A NaN value may be returned if the minority cannot be calculated.

majority

Definition at line 250 of file qgsstatisticalsummary.h.

## ◆ range()

 double QgsStatisticalSummary::range ( ) const
inline

Returns calculated range (difference between maximum and minimum values).

A NaN value may be returned if the range cannot be calculated.

Definition at line 202 of file qgsstatisticalsummary.h.

## ◆ reset()

 void QgsStatisticalSummary::reset ( )

Resets the calculated values.

Definition at line 40 of file qgsstatisticalsummary.cpp.

## ◆ sampleStDev()

 double QgsStatisticalSummary::sampleStDev ( ) const
inline

Returns sample standard deviation.

This is only calculated if Statistic::StDev has been specified in the constructor or via setStatistics. A NaN value may be returned if the standard deviation cannot be calculated.

stDev

Definition at line 234 of file qgsstatisticalsummary.h.

## ◆ setStatistics()

 void QgsStatisticalSummary::setStatistics ( QgsStatisticalSummary::Statistics stats )

Sets flags which specify which statistics will be calculated.

Some statistics are always calculated (e.g., sum, min and max).

Parameters
 stats flags for statistics to calculate
statistics

Definition at line 34 of file qgsstatisticalsummary.cpp.

## ◆ shortName()

 QString QgsStatisticalSummary::shortName ( QgsStatisticalSummary::Statistic statistic )
static

Returns a short, friendly display name for a statistic, suitable for use in a field name.

displayName()
Since
QGIS 3.6

Definition at line 344 of file qgsstatisticalsummary.cpp.

## ◆ statistic()

 double QgsStatisticalSummary::statistic ( QgsStatisticalSummary::Statistic stat ) const

Returns the value of a specified statistic.

Parameters
 stat statistic to return
Returns
calculated value of statistic. A NaN value may be returned for invalid statistics.

Definition at line 252 of file qgsstatisticalsummary.cpp.

## ◆ statistics()

 Statistics QgsStatisticalSummary::statistics ( ) const
inline

Returns flags which specify which statistics will be calculated.

Some statistics are always calculated (e.g., sum, min and max).

setStatistics

Definition at line 85 of file qgsstatisticalsummary.h.

## ◆ stDev()

 double QgsStatisticalSummary::stDev ( ) const
inline

Returns population standard deviation.

This is only calculated if Statistic::StDev has been specified in the constructor or via setStatistics. A NaN value may be returned if the standard deviation cannot be calculated.

sampleStDev

Definition at line 226 of file qgsstatisticalsummary.h.

## ◆ sum()

 double QgsStatisticalSummary::sum ( ) const
inline

Returns calculated sum of values.

Definition at line 171 of file qgsstatisticalsummary.h.

## ◆ thirdQuartile()

 double QgsStatisticalSummary::thirdQuartile ( ) const
inline

Returns the third quartile of the values.

The quartile is calculated using the "Tukey's hinges" method. A NaN value may be returned if the third quartile cannot be calculated.

firstQuartile
interQuartileRange

Definition at line 277 of file qgsstatisticalsummary.h.

## ◆ variety()

 int QgsStatisticalSummary::variety ( ) const
inline

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.

Definition at line 241 of file qgsstatisticalsummary.h.

The documentation for this class was generated from the following files: