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:

Public Member Functions
	QgsZonalStatistics (QgsVectorLayer *polygonLayer, const QString &rasterFile, const QString &attributePrefix="", int rasterBand=1)
	~QgsZonalStatistics ()
int	calculateStatistics (QProgressDialog *p)
	Starts the calculation. More...

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. More...
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) More...
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) More...

Private Attributes
QString	mRasterFilePath
int	mRasterBand
	Raster band to calculate statistics from (defaults to 1) More...
QgsVectorLayer *	mPolygonLayer
QString	mAttributePrefix
float	mInputNodataValue
	The nodata value of the input layer. More...

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.

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.

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::select(), statisticsFromMiddlePointTest_improved(), statisticsFromPreciseIntersection(), TO8, and QgsVectorLayer::updateFieldMap().

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 221 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 245 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 322 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 278 of file qgszonalstatistics.cpp.

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

Referenced by calculateStatistics().

Member Data Documentation

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().

QgsVectorLayer* QgsZonalStatistics::mPolygonLayer

private

Definition at line 61 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().

QString QgsZonalStatistics::mRasterFilePath

private

Definition at line 58 of file qgszonalstatistics.h.

Referenced by calculateStatistics().

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

• /build/buildd/qgis-1.7.4+1.7.5~20120320/src/analysis/vector/qgszonalstatistics.h
• /build/buildd/qgis-1.7.4+1.7.5~20120320/src/analysis/vector/qgszonalstatistics.cpp