jiayuasu commented on code in PR #1124:
URL: https://github.com/apache/sedona/pull/1124#discussion_r1401408332
##########
common/src/main/java/org/apache/sedona/common/raster/RasterBandAccessors.java:
##########
@@ -81,6 +88,190 @@ public static long getCount(GridCoverage2D raster, int
band) {
// return getCount(raster, 1, excludeNoDataValue);
// }
+ /**
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @param band Band to be used for computation
+ * @param excludeNoData Specifies whether to exclude no-data value or not
+ * @return An array with all the stats for the region
+ * @throws FactoryException
+ */
+ public static double[] getZonalStatsAll(GridCoverage2D raster, Geometry
roi, int band, boolean excludeNoData) throws FactoryException {
+ List<Object> objects = getStatObjects(raster, roi, band,
excludeNoData);
+ DescriptiveStatistics stats = (DescriptiveStatistics) objects.get(0);
+ double[] pixelData = (double[]) objects.get(1);
+
+ // order of stats
+ // count, sum, mean, median, mode, stddev, variance, min, max
+ double[] result = new double[9];
+ result[0] = stats.getN();
+ result[1] = stats.getSum();
+ result[2] = stats.getMean();
+ result[3] = stats.getPercentile(50);
+ result[4] = zonalMode(pixelData);
+ result[5] = stats.getStandardDeviation();
+ result[6] = stats.getVariance();
+ result[7] = stats.getMin();
+ result[8] = stats.getMax();
+
+ return result;
+ }
+
+ /**
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @param band Band to be used for computation
+ * @return An array with all the stats for the region, excludeNoData is
set to true
+ * @throws FactoryException
+ */
+ public static double[] getZonalStatsAll(GridCoverage2D raster, Geometry
roi, int band) throws FactoryException {
+ return getZonalStatsAll(raster, roi, band, true);
+ }
+
+ /**
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @return An array with all the stats for the region, excludeNoData is
set to true and band is set to 1
+ * @throws FactoryException
+ */
+ public static double[] getZonalStatsAll(GridCoverage2D raster, Geometry
roi) throws FactoryException {
+ return getZonalStatsAll(raster, roi, 1, true);
+ }
+
+ /**
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @param band Band to be used for computation
+ * @param statType Define the statistic to be computed
+ * @param excludeNoData Specifies whether to exclude no-data value or not
+ * @return A double precision floating point number representing the
requested statistic calculated over the specified region.
+ * @throws FactoryException
+ */
+ public static double getZonalStats(GridCoverage2D raster, Geometry roi,
int band, String statType, boolean excludeNoData) throws FactoryException {
+
+ List<Object> objects = getStatObjects(raster, roi, band,
excludeNoData);
+ DescriptiveStatistics stats = (DescriptiveStatistics) objects.get(0);
+ double[] pixelData = (double[]) objects.get(1);
+
+ switch (statType.toLowerCase()) {
+ case "sum":
+ return stats.getSum();
+ case "average":
+ case "avg":
+ case "mean":
+ return stats.getMean();
+ case "count":
+ return stats.getN();
+ case "max":
+ return stats.getMax();
+ case "min":
+ return stats.getMin();
+ case "stddev":
+ case "sd":
+ return stats.getStandardDeviation();
+ case "median":
+ return stats.getPercentile(50);
+ case "mode":
+ return zonalMode(pixelData);
+ case "variance":
+ return stats.getVariance();
+ default:
+ throw new IllegalArgumentException("Please select from the
accepted options. Some of the valid options are sum, mean, stddev, etc.");
+ }
+ }
+
+ /**
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @param band Band to be used for computation
+ * @param statType Define the statistic to be computed
+ * @return A double precision floating point number representing the
requested statistic calculated over the specified region. The excludeNoData is
set to true.
+ * @throws FactoryException
+ */
+ public static double getZonalStats(GridCoverage2D raster, Geometry roi,
int band, String statType) throws FactoryException {
+ return getZonalStats(raster, roi, band, statType, true);
+ }
+
+ /**
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @param statType Define the statistic to be computed
+ * @return A double precision floating point number representing the
requested statistic calculated over the specified region. The excludeNoData is
set to true and band is set to 1.
+ * @throws FactoryException
+ */
+ public static double getZonalStats(GridCoverage2D raster, Geometry roi,
String statType) throws FactoryException {
+ return getZonalStats(raster, roi, 1, statType, true);
+ }
+
+ /**
+ * @param pixelData An array of double with pixel values
+ * @return Mode of the pixel values. If there is multiple with same
occurrence, then the largest value will be returned.
+ */
+ private static double zonalMode(double[] pixelData) {
+ double[] modes = StatUtils.mode(pixelData);
+ return modes[modes.length - 1];
+ }
+
+ /**
+ * An intermediate function to compute zonal statistics
+ * @param raster Raster to use for computing stats
+ * @param roi Geometry to define the region of interest
+ * @param band Band to be used for computation
+ * @param excludeNoData Specifies whether to exclude no-data value or not
+ * @return an object of DescriptiveStatistics and an array of double with
pixel data.
+ * @throws FactoryException
+ */
+ private static List<Object> getStatObjects(GridCoverage2D raster, Geometry
roi, int band, boolean excludeNoData) throws FactoryException {
+ RasterUtils.ensureBand(raster, band);
+
+ if(RasterAccessors.srid(raster) != roi.getSRID()) {
+ // implicitly converting roi geometry CRS to raster CRS
+ roi = RasterUtils.convertCRSIfNeeded(roi,
raster.getCoordinateReferenceSystem());
+ // have to set the SRID as RasterUtils.convertCRSIfNeeded doesn't
set it even though the geometry is in raster's CRS
+ roi = Functions.setSRID(roi, RasterAccessors.srid(raster));
+ }
+
+ // checking if the raster contains the geometry
+ if (!RasterPredicates.rsIntersects(raster, roi)) {
+ throw new IllegalArgumentException("The provided geometry is not
intersecting the raster. Please provide a geometry that is in the raster's
extent.");
+ }
+
+ Raster rasterData = RasterUtils.getRaster(raster.getRenderedImage());
+ String datatype = RasterBandAccessors.getBandType(raster, band);
+ Double noDataValue = RasterBandAccessors.getBandNoDataValue(raster,
band);
+ // Adding an arbitrary value '150' for the pixels that are under the
geometry.
+ GridCoverage2D rasterizedGeom =
RasterConstructors.asRasterWithRasterExtent(roi, raster, datatype, 150, null);
Review Comment:
@furqaankhan Will it collide with existing values in a raster? If not, we
are good.
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