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. More...
virtual	~QgsStatisticalSummary ()=default
void	addValue (double value)
	Adds a single value to the statistics calculation. More...
void	addVariant (const QVariant &value)
	Adds a single value to the statistics calculation. More...
void	calculate (const QList< double > &values)
	Calculates summary statistics for a list of values. More...
int	count () const
	Returns calculated count of values. More...
int	countMissing () const
	Returns the number of missing (null) values. More...
void	finalize ()
	Must be called after adding all values with addValues() and before retrieving any calculated statistics. More...
double	first () const
	Returns the first value obtained. More...
double	firstQuartile () const
	Returns the first quartile of the values. More...
double	interQuartileRange () const
	Returns the inter quartile range of the values. More...
double	last () const
	Returns the last value obtained. More...
double	majority () const
	Returns majority of values. More...
double	max () const
	Returns calculated maximum from values. More...
double	mean () const
	Returns calculated mean of values. More...
double	median () const
	Returns calculated median of values. More...
double	min () const
	Returns calculated minimum from values. More...
double	minority () const
	Returns minority of values. More...
double	range () const
	Returns calculated range (difference between maximum and minimum values). More...
void	reset ()
	Resets the calculated values. More...
double	sampleStDev () const
	Returns sample standard deviation. More...
void	setStatistics (QgsStatisticalSummary::Statistics stats)
	Sets flags which specify which statistics will be calculated. More...
double	statistic (QgsStatisticalSummary::Statistic stat) const
	Returns the value of a specified statistic. More...
Statistics	statistics () const
	Returns flags which specify which statistics will be calculated. More...
double	stDev () const
	Returns population standard deviation. More...
double	sum () const
	Returns calculated sum of values. More...
double	thirdQuartile () const
	Returns the third quartile of the values. More...
int	variety () const
	Returns variety of values. More...

Static Public Member Functions
static QString	displayName (QgsStatisticalSummary::Statistic statistic)
	Returns the friendly display name for a statistic. More...
static QString	shortName (QgsStatisticalSummary::Statistic statistic)
	Returns a short, friendly display name for a statistic, suitable for use in a field name. More...

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.

Member Enumeration Documentation

Statistic

enum QgsStatisticalSummary::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.

Constructor & Destructor Documentation

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

addValue()

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

value

value to add

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.

See also

calculate()

addVariant()

finalize()

Since

QGIS 2.16

Definition at line 85 of file qgsstatisticalsummary.cpp.

addVariant()

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.

See also

addValue()

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.

See also

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.

See also

addValue()

addVariant()

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.

See also

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.

See also

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.

See also

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.

See also

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.

See also

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.

See also

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.

See also

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

See also

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.

See also

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).

See also

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.

See also

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.

See also

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.

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

• /build/qgis-3.28.0+99sid/src/core/qgsstatisticalsummary.h
• /build/qgis-3.28.0+99sid/src/core/qgsstatisticalsummary.cpp