[SEDONA-355] Add RS_BandPixelType

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

@@ -24,9 +24,7 @@
 public class RasterBandAccessors {
 
     public static Double getBandNoDataValue(GridCoverage2D raster, int band) {
-        if (band > raster.getNumSampleDimensions()) {
-            throw new IllegalArgumentException("Provided band index is not present in the raster");
-        }
+        ensureBand(raster, band);
         GridSampleDimension bandSampleDimension = raster.getSampleDimension(band - 1);
         if (bandSampleDimension.getNoDataValues() == null) return null;
         return raster.getSampleDimension(band - 1).getNoDataValues()[0];
@@ -35,4 +33,20 @@ public static Double getBandNoDataValue(GridCoverage2D raster, int band) {
     public static Double getBandNoDataValue(GridCoverage2D raster) {
         return getBandNoDataValue(raster, 1);
     }
+
+    public static String getBandType(GridCoverage2D raster, int band) {
+        ensureBand(raster, band);
+        GridSampleDimension bandSampleDimension = raster.getSampleDimension(band - 1);
+        return bandSampleDimension.getSampleDimensionType().name();
+    }
+
+    public static String getBandType(GridCoverage2D raster){
+        return getBandType(raster, 1);
+    }
+
+    private static void ensureBand(GridCoverage2D raster, int band) throws IllegalArgumentException {
+        if (band > RasterAccessors.numBands(raster)) {
+            throw new IllegalArgumentException(String.format("Provided band index %d is not present in the raster", band));
+        }
+    }
 }

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

@@ -157,7 +157,7 @@ private static int getDataTypeCode(String s) {
                 return 0;
             case "f":
                 return 4;
-            case "u":
+            case "s":
                 return 2;
             case "us":
                 return 1;

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

@@ -59,7 +59,7 @@ public void testBandNoDataValueDefaultBand() throws FactoryException {
     @Test
     public void testBandNoDataValueDefaultNoData() throws FactoryException {
         int width = 5, height = 10;
-        GridCoverage2D emptyRaster = RasterConstructors.makeEmptyRaster(1, width, height, 53, 51, 1, 1, 0, 0, 4326);
+        GridCoverage2D emptyRaster = RasterConstructors.makeEmptyRaster(1,"I", width, height, 53, 51, 1, 1, 0, 0, 0);
         double[] values = new double[width * height];
         for (int i = 0; i < values.length; i++) {
             values[i] = i + 1;
@@ -71,7 +71,88 @@ public void testBandNoDataValueDefaultNoData() throws FactoryException {
     public void testBandNoDataValueIllegalBand() throws FactoryException, IOException {
         GridCoverage2D raster = rasterFromGeoTiff(resourceFolder + "raster/raster_with_no_data/test5.tiff");
         IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> RasterBandAccessors.getBandNoDataValue(raster, 2));
-        assertEquals("Provided band index is not present in the raster", exception.getMessage());
+        assertEquals("Provided band index 2 is not present in the raster", exception.getMessage());
     }
 
+    @Test
+    public void testBandPixelType() throws FactoryException {
+        double[] values = new double[]{1.2, 1.1, 32.2, 43.2};
+
+        //create double raster
+        GridCoverage2D emptyRaster = RasterConstructors.makeEmptyRaster(2, "D", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        emptyRaster = MapAlgebra.addBandFromArray(emptyRaster, values, 1, 0.0);
+        assertEquals("REAL_64BITS", RasterBandAccessors.getBandType(emptyRaster));
+        assertEquals("REAL_64BITS", RasterBandAccessors.getBandType(emptyRaster, 2));
+        double[] bandValues = MapAlgebra.bandAsArray(emptyRaster, 1);
+        double[] expectedBandValuesD = new double[]{1, 1, 32, 43};
+        for (int i = 0; i < bandValues.length; i++) {
+            assertEquals(expectedBandValuesD[i], bandValues[i], 1e-9);
+        }
+        //create float raster
+        emptyRaster = RasterConstructors.makeEmptyRaster(2, "F", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        emptyRaster = MapAlgebra.addBandFromArray(emptyRaster, values, 1, 0.0);
+        assertEquals("REAL_32BITS", RasterBandAccessors.getBandType(emptyRaster));
+        assertEquals("REAL_32BITS", RasterBandAccessors.getBandType(emptyRaster, 2));
+        bandValues = MapAlgebra.bandAsArray(emptyRaster, 1);
+        float[] expectedBandValuesF = new float[]{1, 1, 32, 43};
+        for (int i = 0; i < bandValues.length; i++) {
+            assertEquals(expectedBandValuesF[i], bandValues[i], 1e-9);
+        }
+
+        //create integer raster
+        emptyRaster = RasterConstructors.makeEmptyRaster(2, "I", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        emptyRaster = MapAlgebra.addBandFromArray(emptyRaster, values, 1, 0.0);
+        assertEquals("SIGNED_32BITS", RasterBandAccessors.getBandType(emptyRaster));
+        assertEquals("SIGNED_32BITS", RasterBandAccessors.getBandType(emptyRaster, 2));
+        bandValues = MapAlgebra.bandAsArray(emptyRaster, 1);
+        int[] expectedBandValuesI = new int[]{1, 1, 32, 43};
+        for (int i = 0; i < bandValues.length; i++) {
+            assertEquals(expectedBandValuesI[i], bandValues[i], 1e-9);
+        }
+
+        //create byte raster
+        emptyRaster = RasterConstructors.makeEmptyRaster(2, "B", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        emptyRaster = MapAlgebra.addBandFromArray(emptyRaster, values, 1, 0.0);
+        bandValues = MapAlgebra.bandAsArray(emptyRaster, 1);
+        assertEquals("UNSIGNED_8BITS", RasterBandAccessors.getBandType(emptyRaster));
+        assertEquals("UNSIGNED_8BITS", RasterBandAccessors.getBandType(emptyRaster, 2));
+        byte[] expectedBandValuesB = new byte[]{1, 1, 32, 43};
+        for (int i = 0; i < bandValues.length; i++) {
+            assertEquals(expectedBandValuesB[i], bandValues[i], 1e-9);
+        }
+
+        //create short raster
+        emptyRaster = RasterConstructors.makeEmptyRaster(2, "S", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        emptyRaster = MapAlgebra.addBandFromArray(emptyRaster, values, 1, 0.0);
+        assertEquals("SIGNED_16BITS", RasterBandAccessors.getBandType(emptyRaster));
+        assertEquals("SIGNED_16BITS", RasterBandAccessors.getBandType(emptyRaster, 2));
+        bandValues = MapAlgebra.bandAsArray(emptyRaster, 1);
+        short[] expectedBandValuesS = new short[]{1, 1, 32, 43};
+        for (int i = 0; i < bandValues.length; i++) {
+            assertEquals(expectedBandValuesS[i], bandValues[i], 1e-9);
+        }
+
+        //create unsigned short raster
+        values = new double[]{-1.2, 1.1, -32.2, 43.2};
+        emptyRaster = RasterConstructors.makeEmptyRaster(2, "US", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        emptyRaster = MapAlgebra.addBandFromArray(emptyRaster, values, 1, 0.0);
+        assertEquals("UNSIGNED_16BITS", RasterBandAccessors.getBandType(emptyRaster));
+        assertEquals("UNSIGNED_16BITS", RasterBandAccessors.getBandType(emptyRaster, 2));
+        bandValues = MapAlgebra.bandAsArray(emptyRaster, 1);
+
+        short[] expectedBandValuesUS = new short[]{-1, 1, -32, 43};
+        for (int i = 0; i < bandValues.length; i++) {
+            assertEquals(Short.toUnsignedInt(expectedBandValuesUS[i]), Short.toUnsignedInt((short) bandValues[i]), 1e-9);
+        }
+    }
+
+    @Test
+    public void testBandPixelTypeIllegalBand() throws FactoryException {
+        GridCoverage2D emptyRaster = RasterConstructors.makeEmptyRaster(2, "US", 2, 2, 53, 51, 1, 1, 0, 0, 0);
+        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> RasterBandAccessors.getBandType(emptyRaster, 5));
+        assertEquals("Provided band index 5 is not present in the raster", exception.getMessage());
+    }
+
+
+
 }

docs/api/sql/Raster-operators.md

@@ -339,7 +339,46 @@ Output: `null`
 SELECT RS_BandNoDataValue(raster, 3) from rasters;
 ```
 
-Output: `IllegalArgumentException: Provided band index is not present in the raster.`
+Output: `IllegalArgumentException: Provided band index 3 is not present in the raster.`
+
+### RS_BandPixelType
+
+Introduction: Returns the datatype of each pixel in the given band of the given raster in string format. The band parameter is 1-indexed. If no band is specified, band 1 is assumed.
+!!!Note
+    If the given band index does not exist in the given raster, RS_BandPixelType throws an IllegalArgumentException.
+Following are the possible values returned by RS_BandPixelType:
+
+
+1. `REAL_64BITS` - For Double values
+2. `REAL_32BITS` - For Float values
+3. `SIGNED_32BITS` - For Integer values
+4. `SIGNED_16BITS` - For Short values
+5. `UNSIGNED_16BITS` - For unsigned Short values
+6. `UNSIGNED_8BITS` - For Byte values
+
+
+Format: `RS_BandPixelType(rast: Raster, band: Int = 1)`
+
+Since: `1.5.0`
+
+Spark SQL example:
+```sql
+SELECT RS_BandPixelType(RS_MakeEmptyRaster(2, "D", 5, 5, 53, 51, 1, 1, 0, 0, 0), 2);
+```
+
+Output: `REAL_64BITS`
+
+```sql
+SELECT RS_BandPixelType(RS_MakeEmptyRaster(2, "I", 5, 5, 53, 51, 1, 1, 0, 0, 0));
+```
+
+Output: `SIGNED_32BITS`
+
+```sql
+SELECT RS_BandPixelType(RS_MakeEmptyRaster(2, "I", 5, 5, 53, 51, 1, 1, 0, 0, 0), 3);
+```
+
+Output: `IllegalArgumentException: Provided band index 3 is not present in the raster`
 
 
 ## Raster based operators

sql/common/src/main/scala/org/apache/sedona/sql/UDF/Catalog.scala

@@ -223,7 +223,8 @@ object Catalog {
     function[RS_WorldToRasterCoord](),
     function[RS_WorldToRasterCoordX](),
     function[RS_WorldToRasterCoordY](),
-    function[RS_BandNoDataValue]()
+    function[RS_BandNoDataValue](),
+    function[RS_BandPixelType]()
   )
 
   val aggregateExpressions: Seq[Aggregator[Geometry, Geometry, Geometry]] = Seq(

sql/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/raster/RasterBandAccessors.scala

@@ -30,3 +30,9 @@ case class RS_BandNoDataValue(inputExpressions: Seq[Expression]) extends Inferre
   }
 }
 
+case class RS_BandPixelType(inputExpressions: Seq[Expression]) extends InferredExpression(inferrableFunction2(RasterBandAccessors.getBandType), inferrableFunction1(RasterBandAccessors.getBandType)) {
+  protected def withNewChildrenInternal(newChildren: IndexedSeq[Expression]) = {
+    copy(inputExpressions = newChildren)
+  }
+}
+

sql/common/src/test/scala/org/apache/sedona/sql/rasteralgebraTest.scala

@@ -18,7 +18,6 @@
  */
 package org.apache.sedona.sql
 
-import org.apache.spark.sql.connector.catalog.TableChange.ColumnPosition.first
 import org.apache.spark.sql.functions.{collect_list, expr}
 import org.geotools.coverage.grid.GridCoverage2D
 import org.junit.Assert.{assertEquals, assertNull}
@@ -693,5 +692,18 @@ class rasteralgebraTest extends TestBaseScala with BeforeAndAfter with GivenWhen
       assertEquals(0, result, 1e-9)
     }
 
+    it("Passed RS_BandPixelType from raster") {
+      var df = sparkSession.read.format("binaryFile").load(resourceFolder + "raster/raster_with_no_data/test5.tiff")
+      df = df.selectExpr("RS_FromGeoTiff(content) as raster")
+      val result = df.selectExpr("RS_BandPixelType(raster, 1)").first().getString(0)
+      assertEquals("UNSIGNED_8BITS", result)
+    }
+
+    it("Passed RS_BandPixelType from raster - default band value") {
+      var df = sparkSession.read.format("binaryFile").load(resourceFolder + "raster/raster_with_no_data/test5.tiff")
+      df = df.selectExpr("RS_FromGeoTiff(content) as raster")
+      val result = df.selectExpr("RS_BandPixelType(raster)").first().getString(0)
+      assertEquals("UNSIGNED_8BITS", result)
+    }
   }
 }