Class: QgsZonalStatistics

class qgis.analysis.QgsZonalStatistics

Bases: sip.wrapper

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

QgsZonalStatistics(polygonLayer: QgsVectorLayer, rasterLayer: QgsRasterLayer, attributePrefix: str = ‘’, rasterBand: int = 1, stats: Union[Qgis.ZonalStatistics, Qgis.ZonalStatistic] = Qgis.ZonalStatistic.Default) Convenience constructor for QgsZonalStatistics, using an input raster layer.

The raster layer must exist for the lifetime of the zonal statistics calculation.

Warning

Constructing QgsZonalStatistics using this method is not thread safe, and the constructor which accepts a QgsRasterInterface should be used instead.

QgsZonalStatistics(polygonLayer: QgsVectorLayer, rasterInterface: QgsRasterInterface, rasterCrs: QgsCoordinateReferenceSystem, rasterUnitsPerPixelX: float, rasterUnitsPerPixelY: float, attributePrefix: str = ‘’, rasterBand: int = 1, stats: Union[Qgis.ZonalStatistics, Qgis.ZonalStatistic] = Qgis.ZonalStatistic.Default) Constructor for QgsZonalStatistics, using a QgsRasterInterface.

The polygonLayer gives the vector layer containing the (multi)polygon features corresponding to the different zones. This layer will be modified, adding extra attributes for each of the zonal statistics calculated.

Pixel values for each zone are taken from the raster rasterInterface. The constructor must also be given various properties relating to the input raster, such as the raster CRS (rasterCrs), and the size (X and Y) in map units for each raster pixel. The source raster band is specified via rasterBand, where a value of 1 corresponds to the first band.

If the CRS of the polygonLayer and rasterCrs differ, the calculation will automatically reproject the zones to ensure valid results are calculated.

The attributePrefix argument specifies an optional prefix to use when creating the new fields for each calculated statistic.

Finally, the calculated statistics can be set via the stats argument. A new field will be added to polygonLayer for each statistic calculated.

Warning

The raster interface must exist for the lifetime of the zonal statistics calculation. For thread safe use, always use a cloned raster interface.

New in version 3.2.

QgsZonalStatistics(QgsZonalStatistics)

Enums

Result

alias of ZonalStatisticResult

Statistic

alias of ZonalStatistic

Methods

calculateStatistics

Runs the calculation.

displayName

Returns the friendly display name for a statistic.

shortName

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

Result

alias of ZonalStatisticResult

Statistic

alias of ZonalStatistic

Statistics

alias of ZonalStatistics

calculateStatistics(self, feedback: QgsFeedback) Qgis.ZonalStatisticResult

Runs the calculation.

calculateStatistics(rasterInterface: QgsRasterInterface, geometry: QgsGeometry, cellSizeX: float, cellSizeY: float, rasterBand: int, statistics: Union[Qgis.ZonalStatistics, Qgis.ZonalStatistic]) -> Dict[int, Any] Calculates the specified statistics for the pixels of rasterBand in rasterInterface (a raster layer dataProvider() ) within polygon geometry.

Returns a map of statistic to result value.

New in version 3.16.

Parameters:

feedback (QgsFeedback) –

Return type:

Qgis.ZonalStatisticResult

displayName(statistic: Qgis.ZonalStatistic) str

Returns the friendly display name for a statistic.

See also

shortName()

New in version 3.12.

Parameters:

statistic (Qgis.ZonalStatistic) –

Return type:

str

shortName(statistic: Qgis.ZonalStatistic) str

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

See also

displayName()

New in version 3.12.

Parameters:

statistic (Qgis.ZonalStatistic) –

Return type:

str