Make PointFeatureExctractor more generic

docs/CHANGELOG.rst

@@ -100,6 +100,8 @@ API Changes & Project structure changes
 
     ``import geotrellis.raster._``
 
+  - **New:** Rasters FeatureExtraction (`#3117 <https://github.com/locationtech/geotrellis/pull/3117>`_):
+
 - ``geotrellis.vectortile``
 
   - **Add:** ``geotrellis.vectortile.MVTFeature`` which properly conforms to the MVT 2.0 spec. Specifically, MVTFeature adds support for an ``Option[Long]`` id property.

raster/src/main/scala/geotrellis/raster/FeatureExtraction.scala → raster/src/main/scala/geotrellis/raster/FeatureExtractor.scala

@@ -23,14 +23,14 @@ import spire.syntax.cfor._
 
 import scala.collection.mutable.ListBuffer
 
-trait FeatureExtraction[I <: Geometry, T <: CellGrid[Int], O <: Geometry, D] {
-  def features(geom: I, raster: Raster[T]): Array[Feature[O, Array[D]]]
+trait FeatureExtractor[I <: Geometry, T <: CellGrid[Int], O <: Geometry, D] {
+  def features(geom: I, raster: Raster[T]): Array[Feature[O, D]]
 }
 
-object FeatureExtraction {
-  def apply[I <: Geometry: FeatureExtraction[*, T, O, D], T <: CellGrid[Int], O <: Geometry, D] = implicitly[FeatureExtraction[I, T, O, D]]
+object FeatureExtractor {
+  def apply[I <: Geometry: FeatureExtractor[*, T, O, D], T <: CellGrid[Int], O <: Geometry, D] = implicitly[FeatureExtractor[I, T, O, D]]
 
-  implicit def multibandTile[I <: Geometry] = new PointFeatureExtraction[I, MultibandTile, Int] {
+  implicit def multibandTile[I <: Geometry] = new PointFeatureExtractor[I, MultibandTile, Array[Int]] {
     def features(geom: I, raster: Raster[MultibandTile]): Array[PointFeature[Array[Int]]] = {
       val buffer = ListBuffer[PointFeature[Array[Int]]]()
 
@@ -44,7 +44,7 @@ object FeatureExtraction {
     }
   }
 
-  implicit def multibandTileDouble[I <: Geometry] = new PointFeatureExtraction[I, MultibandTile, Double] {
+  implicit def multibandTileDouble[I <: Geometry] = new PointFeatureExtractor[I, MultibandTile, Array[Double]] {
     def features(geom: I, raster: Raster[MultibandTile]): Array[PointFeature[Array[Double]]] = {
       val buffer = ListBuffer[PointFeature[Array[Double]]]()
 
@@ -58,14 +58,14 @@ object FeatureExtraction {
     }
   }
 
-  implicit def tile[I <: Geometry] = new PointFeatureExtraction[I, Tile, Int] {
-    def features(geom: I, raster: Raster[Tile]): Array[PointFeature[Array[Int]]] =
-      multibandTile[I].features(geom, raster.mapTile(MultibandTile(_)))
+  implicit def tile[I <: Geometry] = new PointFeatureExtractor[I, Tile, Int] {
+    def features(geom: I, raster: Raster[Tile]): Array[PointFeature[Int]] =
+      multibandTile[I].features(geom, raster.mapTile(MultibandTile(_))).map(_.mapData(_.head))
   }
 
-  implicit def tileDouble[I <: Geometry] = new PointFeatureExtraction[I, Tile, Double] {
-    def features(geom: I, raster: Raster[Tile]): Array[PointFeature[Array[Double]]] = {
-      multibandTileDouble[I].features(geom, raster.mapTile(MultibandTile(_)))
+  implicit def tileDouble[I <: Geometry] = new PointFeatureExtractor[I, Tile, Double] {
+    def features(geom: I, raster: Raster[Tile]): Array[PointFeature[Double]] = {
+      multibandTileDouble[I].features(geom, raster.mapTile(MultibandTile(_))).map(_.mapData(_.head))
     }
   }
 }

raster/src/main/scala/geotrellis/raster/Implicits.scala

@@ -125,17 +125,17 @@ trait Implicits
     }
   }
 
-  implicit class MultibandRasterPointFeatureExtractionMethods(val self: Raster[MultibandTile]) extends MethodExtensions[Raster[MultibandTile]] {
+  implicit class MultibandRasterPointFeatureExtractorMethods(val self: Raster[MultibandTile]) extends MethodExtensions[Raster[MultibandTile]] {
     def pointFeatures[D] = new {
-      def apply[I <: Geometry: PointFeatureExtraction[*, MultibandTile, D]](geom: I): Array[PointFeature[Array[D]]] =
-        FeatureExtraction[I, MultibandTile, Point, D].features(geom, self)
+      def apply[I <: Geometry: PointFeatureExtractor[*, MultibandTile, Array[D]]](geom: I): Array[PointFeature[Array[D]]] =
+        FeatureExtractor[I, MultibandTile, Point, Array[D]].features(geom, self)
     }
   }
 
-  implicit class rasterPointFeatureExtractionMethods(val self: Raster[Tile]) extends MethodExtensions[Raster[Tile]] {
+  implicit class RasterPointFeatureExtractorMethods(val self: Raster[Tile]) extends MethodExtensions[Raster[Tile]] {
     def pointFeatures[D] = new {
-      def apply[I <: Geometry: PointFeatureExtraction[*, Tile, D]](geom: I): Array[PointFeature[D]] =
-        FeatureExtraction[I, Tile, Point, D].features(geom, self).map(_.mapData(_.head))
+      def apply[I <: Geometry: PointFeatureExtractor[*, Tile, D]](geom: I): Array[PointFeature[D]] =
+        FeatureExtractor[I, Tile, Point, D].features(geom, self)
     }
   }
 }

raster/src/main/scala/geotrellis/raster/package.scala

@@ -185,7 +185,7 @@ package object raster extends Implicits {
     def fill(v: Double) = { java.util.Arrays.fill(arr, v) ; arr }
   }
 
-  type PointFeatureExtraction[I <: Geometry, T <: CellGrid[Int], D] = FeatureExtraction[I, T, Point, D]
+  type PointFeatureExtractor[I <: Geometry, T <: CellGrid[Int], D] = FeatureExtractor[I, T, Point, D]
 
   /* http://stackoverflow.com/questions/3508077/how-to-define-type-disjunction-union-types */
   sealed class TileOrMultibandTile[T]

raster/src/test/scala/geotrellis/raster/FeatureExtractionSpec.scala → raster/src/test/scala/geotrellis/raster/FeatureExtractorSpec.scala

@@ -21,7 +21,7 @@ import geotrellis.raster.testkit._
 
 import org.scalatest._
 
-class FeatureExtractionSpec extends FunSpec with Matchers {
+class FeatureExtractorSpec extends FunSpec with Matchers {
   describe("Tile") {
     it("should extract all int point features") {
       val ext = Extent(0.0, 0.0, 3.0, 3.0)