Class: QgsZonalStatistics

class qgis.analysis.QgsZonalStatistics(polygonLayer: QgsVectorLayer, rasterLayer: QgsRasterLayer, attributePrefix: str = '', rasterBand: int = 1, stats: Union[QgsZonalStatistics.Statistics, QgsZonalStatistics.Statistic] = QgsZonalStatistics.Statistics(QgsZonalStatistics.Count|QgsZonalStatistics.Sum|QgsZonalStatistics.Mean))

Bases: sip.wrapper

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[QgsZonalStatistics.Statistics, QgsZonalStatistics.Statistic] = QgsZonalStatistics.Statistics(QgsZonalStatistics.Count|QgsZonalStatistics.Sum|QgsZonalStatistics.Mean)) 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)

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

Enums

Methods

calculateStatistics Starts the calculation

Signals

Attributes

All
Count
Majority
Max
Mean
Median
Min
Minority
Range
StDev
Sum
Variance
Variety
All = 4095
Count = 1
Majority = 512
Max = 64
Mean = 4
Median = 8
Min = 32
Minority = 256
Range = 128
StDev = 16
class Statistic

Bases: int

class Statistics

Bases: sip.wrapper

QgsZonalStatistics.Statistics(Union[QgsZonalStatistics.Statistics, QgsZonalStatistics.Statistic]) QgsZonalStatistics.Statistics(QgsZonalStatistics.Statistics)

Sum = 2
Variance = 2048
Variety = 1024
calculateStatistics(self, feedback: QgsFeedback) → int

Starts the calculation

Returns:0 in case of success