fix: RS_ZonalStats and RS_ZonalStatsAll edge case

Author: furqaankhan

common/src/main/java/org/apache/sedona/common/raster/RasterBandAccessors.java

@@ -114,6 +114,13 @@ public static double[] getZonalStatsAll(
     DescriptiveStatistics stats = (DescriptiveStatistics) objects.get(0);
     double[] pixelData = (double[]) objects.get(1);
 
+    // Shortcut for an edge case where ROI barely intersects with raster's extent, but it doesn't intersect with the
+    // centroid of the pixel.
+    // This happens when allTouched parameter is false.
+    if (pixelData.length == 0) {
+      return new double[] {0, 0, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN};
+    }
+
     // order of stats
     // count, sum, mean, median, mode, stddev, variance, min, max
     double[] result = new double[9];
@@ -312,6 +319,11 @@ public static Double getZonalStats(GridCoverage2D raster, Geometry roi, String s
    */
   private static double zonalMode(double[] pixelData) {
     double[] modes = StatUtils.mode(pixelData);
+    // Return NaN when ROI and raster's extent overlap, but there's no pixel data.
+    // This behavior only happens when allTouched parameter is false.
+    if (modes.length == 0) {
+      return Double.NaN;
+    }
     return modes[modes.length - 1];
   }
 

common/src/test/java/org/apache/sedona/common/raster/RasterBandAccessorsTest.java

@@ -84,6 +84,23 @@ public void testBandNoDataValueIllegalBand() throws FactoryException, IOExceptio
     assertEquals("Provided band index 2 is not present in the raster", exception.getMessage());
   }
 
+  @Test
+  public void testZonalStatsIntersectingNoPixelData() throws FactoryException, ParseException {
+    double[][] pixelsValues = new double[][] {
+            new double[] {3, 7, 5, 40, 61, 70, 60, 80, 27, 55, 35, 44, 21, 36, 53, 54, 86, 28, 45, 24, 99, 22, 18, 98, 10}
+    };
+    GridCoverage2D raster = RasterConstructors.makeNonEmptyRaster(1, "", 5, 5, 1, -1, 1, -1, 0, 0, 0, pixelsValues);
+    Geometry extent = Constructors.geomFromWKT("POLYGON ((5.822754 -6.620957, 6.965332 -6.620957, 6.965332 -5.834616, 5.822754 -5.834616, 5.822754 -6.620957))", 0);
+
+    double actualZonalStats = RasterBandAccessors.getZonalStats(raster, extent, "mode");
+    assertTrue(Double.isNaN(actualZonalStats));
+
+
+    double [] actualZonalStatsAll = RasterBandAccessors.getZonalStatsAll(raster, extent);
+    double[] expectedZonalStatsAll = new double[] {0.0, 0.0, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN};
+    assertArrayEquals(expectedZonalStatsAll, actualZonalStatsAll, FP_TOLERANCE);
+  }
+
   @Test
   public void testZonalStats() throws FactoryException, ParseException, IOException {
     GridCoverage2D raster =