QgsZonalStatistics Class Reference

A class that calculates raster statistics (count, sum, mean) for a polygon or multipolygon layer and appends the results as attributes. More...

#include <qgszonalstatistics.h>

Collaboration diagram for QgsZonalStatistics:

[legend]

List of all members.

Public Member Functions
	QgsZonalStatistics (QgsVectorLayer *polygonLayer, const QString &rasterFile, const QString &attributePrefix="", int rasterBand=1)
	~QgsZonalStatistics ()
int	calculateStatistics (QProgressDialog *p)
	Starts the calculation.
Private Member Functions
	QgsZonalStatistics ()
int	cellInfoForBBox (const QgsRectangle &rasterBBox, const QgsRectangle &featureBBox, double cellSizeX, double cellSizeY, int &offsetX, int &offsetY, int &nCellsX, int &nCellsY) const
	Analysis what cells need to be considered to cover the bounding box of a feature.
void	statisticsFromMiddlePointTest (void *band, QgsGeometry *poly, int pixelOffsetX, int pixelOffsetY, int nCellsX, int nCellsY, double cellSizeX, double cellSizeY, const QgsRectangle &rasterBBox, double &sum, double &count)
	Returns statistics by considering the pixels where the center point is within the polygon (fast).
void	statisticsFromMiddlePointTest_improved (void *band, QgsGeometry *poly, int pixelOffsetX, int pixelOffsetY, int nCellsX, int nCellsY, double cellSizeX, double cellSizeY, const QgsRectangle &rasterBBox, double &sum, double &count)
void	statisticsFromPreciseIntersection (void *band, QgsGeometry *poly, int pixelOffsetX, int pixelOffsetY, int nCellsX, int nCellsY, double cellSizeX, double cellSizeY, const QgsRectangle &rasterBBox, double &sum, double &count)
	Returns statistics with precise pixel - polygon intersection test (slow).
Private Attributes
QString	mRasterFilePath
int	mRasterBand
	Raster band to calculate statistics from (defaults to 1).
QgsVectorLayer *	mPolygonLayer
QString	mAttributePrefix
float	mInputNodataValue
	The nodata value of the input layer.

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Detailed Description

A class that calculates raster statistics (count, sum, mean) for a polygon or multipolygon layer and appends the results as attributes.

Definition at line 29 of file qgszonalstatistics.h.

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Constructor & Destructor Documentation

QgsZonalStatistics::QgsZonalStatistics	(	QgsVectorLayer *	polygonLayer,
		const QString &	rasterFile,
		const QString &	attributePrefix = "",
		int	rasterBand = 1
	)

Definition at line 32 of file qgszonalstatistics.cpp.

QgsZonalStatistics::~QgsZonalStatistics

(

)

Definition at line 49 of file qgszonalstatistics.cpp.

QgsZonalStatistics::QgsZonalStatistics

(

)

[private]

Definition at line 42 of file qgszonalstatistics.cpp.

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Member Function Documentation

int QgsZonalStatistics::calculateStatistics

(

QProgressDialog *

p

)

Starts the calculation.

Returns:

0 in case of success

Definition at line 54 of file qgszonalstatistics.cpp.

References QgsVectorDataProvider::addAttributes(), QgsGeometry::boundingBox(), cellInfoForBBox(), QgsVectorDataProvider::changeAttributeValues(), QgsVectorLayer::dataProvider(), QgsVectorDataProvider::featureCount(), QgsVectorDataProvider::fieldNameIndex(), QgsFeature::geometry(), QgsVectorLayer::geometryType(), QgsFeature::id(), mAttributePrefix, mInputNodataValue, mPolygonLayer, mRasterBand, mRasterFilePath, QgsVectorDataProvider::nextFeature(), QGis::Polygon, QgsVectorDataProvider::rewind(), QgsVectorDataProvider::select(), statisticsFromMiddlePointTest_improved(), statisticsFromPreciseIntersection(), and TO8.

int QgsZonalStatistics::cellInfoForBBox	(	const QgsRectangle &	rasterBBox,
		const QgsRectangle &	featureBBox,
		double	cellSizeX,
		double	cellSizeY,
		int &	offsetX,
		int &	offsetY,
		int &	nCellsX,
		int &	nCellsY
	)			const [private]

Analysis what cells need to be considered to cover the bounding box of a feature.

Returns:

0 in case of success

Definition at line 218 of file qgszonalstatistics.cpp.

References QgsRectangle::intersect(), QgsRectangle::isEmpty(), QgsRectangle::xMaximum(), QgsRectangle::xMinimum(), QgsRectangle::yMaximum(), and QgsRectangle::yMinimum().

Referenced by calculateStatistics().

void QgsZonalStatistics::statisticsFromMiddlePointTest	(	void *	band,
		QgsGeometry *	poly,
		int	pixelOffsetX,
		int	pixelOffsetY,
		int	nCellsX,
		int	nCellsY,
		double	cellSizeX,
		double	cellSizeY,
		const QgsRectangle &	rasterBBox,
		double &	sum,
		double &	count
	)			[private]

Returns statistics by considering the pixels where the center point is within the polygon (fast).

Definition at line 242 of file qgszonalstatistics.cpp.

References QgsGeometry::contains(), mInputNodataValue, QgsRectangle::xMinimum(), and QgsRectangle::yMaximum().

void QgsZonalStatistics::statisticsFromMiddlePointTest_improved	(	void *	band,
		QgsGeometry *	poly,
		int	pixelOffsetX,
		int	pixelOffsetY,
		int	nCellsX,
		int	nCellsY,
		double	cellSizeX,
		double	cellSizeY,
		const QgsRectangle &	rasterBBox,
		double &	sum,
		double &	count
	)			[private]

Definition at line 319 of file qgszonalstatistics.cpp.

References QgsGeometry::asGeos(), mInputNodataValue, QgsRectangle::xMinimum(), and QgsRectangle::yMaximum().

Referenced by calculateStatistics().

void QgsZonalStatistics::statisticsFromPreciseIntersection	(	void *	band,
		QgsGeometry *	poly,
		int	pixelOffsetX,
		int	pixelOffsetY,
		int	nCellsX,
		int	nCellsY,
		double	cellSizeX,
		double	cellSizeY,
		const QgsRectangle &	rasterBBox,
		double &	sum,
		double &	count
	)			[private]

Returns statistics with precise pixel - polygon intersection test (slow).

Definition at line 275 of file qgszonalstatistics.cpp.

References QgsGeometry::area(), QgsGeometry::fromRect(), QgsGeometry::intersection(), QgsRectangle::xMinimum(), and QgsRectangle::yMaximum().

Referenced by calculateStatistics().

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Member Data Documentation

QString QgsZonalStatistics::mRasterFilePath [private]

Definition at line 58 of file qgszonalstatistics.h.

Referenced by calculateStatistics().

int QgsZonalStatistics::mRasterBand [private]

Raster band to calculate statistics from (defaults to 1).

Definition at line 60 of file qgszonalstatistics.h.

Referenced by calculateStatistics().

QgsVectorLayer* QgsZonalStatistics::mPolygonLayer [private]

Definition at line 61 of file qgszonalstatistics.h.

Referenced by calculateStatistics().

QString QgsZonalStatistics::mAttributePrefix [private]

Definition at line 62 of file qgszonalstatistics.h.

Referenced by calculateStatistics().

float QgsZonalStatistics::mInputNodataValue [private]

The nodata value of the input layer.

Definition at line 64 of file qgszonalstatistics.h.

Referenced by calculateStatistics(), statisticsFromMiddlePointTest(), and statisticsFromMiddlePointTest_improved().

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

• src/analysis/vector/qgszonalstatistics.h
• src/analysis/vector/qgszonalstatistics.cpp