Subgroup: other
Class: QgsZonalStatistics¶
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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 viarasterBand
, where a value of 1 corresponds to the first band.If the CRS of the
polygonLayer
andrasterCrs
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 topolygonLayer
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.
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All
= 4095¶
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Count
= 1¶
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Majority
= 512¶
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Max
= 64¶
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Mean
= 4¶
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Median
= 8¶
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Min
= 32¶
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Minority
= 256¶
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Range
= 128¶
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StDev
= 16¶
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class
Statistic
¶ Bases:
int
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class
Statistics
¶ Bases:
sip.wrapper
QgsZonalStatistics.Statistics(Union[QgsZonalStatistics.Statistics, QgsZonalStatistics.Statistic]) QgsZonalStatistics.Statistics(QgsZonalStatistics.Statistics)
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Sum
= 2¶
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Variance
= 2048¶
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Variety
= 1024¶
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calculateStatistics
(self, feedback: QgsFeedback) → int¶ Starts the calculation
Returns: 0 in case of success
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