RS_ZonalStats¶

Introduction: This returns a statistic value specified by statType over the region of interest defined by zone. It computes the statistic from the pixel values within the ROI geometry and returns the result. If the excludeNoData parameter is not specified, it will default to true. This excludes NoData values from the statistic calculation. Additionally, if the band parameter is not provided, band 1 will be used by default for the statistic computation. The valid options for statType are:

For polygon geometries, the allTouched parameter (Since v1.7.1) determines how pixels are selected:

When true, pixel selection also includes cells entered by the polygon's boundary, following the RS_AsRaster rules.
When false (default), pixels whose centroid intersects the polygon will be included.

A polygon never selects a pixel it touches only on the pixel's boundary, whichever edge that is. A polygon aligned with grid lines selects only pixels inside it.

Point geometries select the single pixel containing the point under the half-open rule, regardless of allTouched. Line rasterization follows the cells entered by its segments rather than requiring a pixel-centre intersection. A point or line lying on an internal grid edge selects the pixel after it in pixel order; one lying on the raster's last edge selects none. A neighboring pixel contacted only at a line endpoint is not selected unless the segment enters it.

RS_ZonalStats_allTouched

count: Number of pixels in the region.
sum: Sum of pixel values.
mean|average|avg: Arithmetic mean.
median: Middle value in the region.
mode: Most occurring value, if there are multiple values with same occurrence then will return the largest number.
stddev|sd: Standard deviation.
variance: Variance.
min: Minimum value in the region.
max: Maximum value in the region.

Note

If the coordinate reference system (CRS) of the input zone geometry differs from that of the raster, then zone will be transformed to match the CRS of the raster before computation.

The following conditions will throw an IllegalArgumentException if they are not met:

The provided raster and zone geometry should intersect when lenient parameter is set to false.
The option provided to statType should be valid.

lenient parameter is set to true by default. The function will return null if the raster and zone geometry do not intersect.

RS_ZonalStats

Format:

RS_ZonalStats(raster: Raster, zone: Geometry, statType: String)

RS_ZonalStats(raster: Raster, zone: Geometry, band: Integer, statType: String)

RS_ZonalStats(raster: Raster, zone: Geometry, band: Integer, statType: String, allTouched: Boolean)

RS_ZonalStats(raster: Raster, zone: Geometry, band: Integer, statType: String, allTouched: Boolean, excludeNoData: Boolean)

RS_ZonalStats(raster: Raster, zone: Geometry, band: Integer, statType: String, allTouched: Boolean, excludeNoData: Boolean, lenient: Boolean)

Return type: Double

Since: v1.5.1

SQL Example

RS_ZonalStats(rast1, geom1, 1, 'sum', true, false)

Output:

10690406

SQL Example

RS_ZonalStats(rast2, geom2, 1, 'mean', false, true)

Output:

226.55992667794473