perf(geobase): double arrays as List<double> instead of Iterable<doub…

…le> in Position, Box and PositionSeries #200, #203
navibyte · Sep 13, 2023 · 6c2d1fa · 6c2d1fa
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diff --git a/dart/geobase/CHANGELOG.md b/dart/geobase/CHANGELOG.md
@@ -8,6 +8,7 @@ NOTE: Version 0.6.0 currently [under development](https://github.com/navibyte/ge
 * [Testing feature and geometry equality #188](https://github.com/navibyte/geospatial/issues/188)
 * [Factories on Position and Box to create from double arrays #199](https://github.com/navibyte/geospatial/issues/199)
 * [Redesigned PositionData supporting positions from coordinate value array and position objects #200](https://github.com/navibyte/geospatial/issues/200)
+* [Coordinates using data structures from typed data #203](https://github.com/navibyte/geospatial/issues/203)
 
 ⚠️ Breaking changes:
 * [Allow a position stored as "Position" in Point, and a bounding box as "Box" in Geometry classes #192](https://github.com/navibyte/geospatial/issues/192)

diff --git a/dart/geobase/lib/src/coordinates/base/box.dart b/dart/geobase/lib/src/coordinates/base/box.dart
@@ -89,9 +89,6 @@ abstract class Box extends Positionable {
 
   /// A bounding box with coordinate values as a view backed by [source].
   ///
-  /// A double iterable of [source] may be represented by a [List] or any
-  /// [Iterable] with efficient `length` and `elementAt` implementations.
-  ///
   /// The [source] must contain 4, 6 or 8 coordinate values. Supported
   /// coordinate value combinations by coordinate [type] are:
   ///
@@ -110,7 +107,7 @@ abstract class Box extends Positionable {
   /// xyz  | west, south, minElev, east, north, maxElev
   /// xym  | west, south, minM, east, north, maxM
   /// xyzm | west, south, minElev, minM, east, north, maxElev, maxM
-  factory Box.view(Iterable<double> source, {Coords? type}) {
+  factory Box.view(List<double> source, {Coords? type}) {
     final coordType = type ?? Coords.fromDimension(source.length ~/ 2);
     if (source.length != 2 * coordType.coordinateDimension) {
       throw invalidCoordinates;
@@ -943,6 +940,9 @@ class _BoxCoords extends Box {
   final Coords _type;
 
   /// A bounding box with coordinate values of [type] from [source].
+  ///
+  /// A double iterable of [source] may be represented by a [List] or any
+  /// [Iterable] with efficient `length` and `elementAt` implementations.
   const _BoxCoords.view(Iterable<double> source, {Coords type = Coords.xy})
       : _data = source,
         _type = type;

diff --git a/dart/geobase/lib/src/coordinates/base/position.dart b/dart/geobase/lib/src/coordinates/base/position.dart
@@ -99,9 +99,6 @@ abstract class Position extends Positionable {
 
   /// A position with coordinate values as a view backed by [source].
   ///
-  /// A double iterable of [source] may be represented by a [List] or any
-  /// [Iterable] with efficient `length` and `elementAt` implementations.
-  ///
   /// The [source] must contain 2, 3 or 4 coordinate values. Supported
   /// coordinate value combinations by coordinate [type] are:
   ///
@@ -120,7 +117,7 @@ abstract class Position extends Positionable {
   /// xyz  | lon, lat, elev
   /// xym  | lon, lat, m
   /// xyzm | lon, lat, elev, m
-  factory Position.view(Iterable<double> source, {Coords? type}) {
+  factory Position.view(List<double> source, {Coords? type}) {
     final len = source.length;
     final coordType = type ?? Coords.fromDimension(len);
     if (len != coordType.coordinateDimension) {
@@ -733,6 +730,9 @@ class _PositionCoords extends Position {
   final Coords _type;
 
   /// A position with coordinate values of [type] from [source].
+  ///
+  /// A double iterable of [source] may be represented by a [List] or any
+  /// [Iterable] with efficient `length` and `elementAt` implementations.
   const _PositionCoords.view(Iterable<double> source, {required Coords type})
       : _data = source,
         _type = type;

diff --git a/dart/geobase/lib/src/coordinates/base/position_series.dart b/dart/geobase/lib/src/coordinates/base/position_series.dart
@@ -62,14 +62,9 @@ abstract class PositionSeries implements Positionable {
   /// less coordinate values than `type.coordinateDimension`, then the view is
   /// considered empty.
   ///
-  /// An iterable collection of [source] may be represented by a [List] or any
-  /// [Iterable] with efficient `length` and `elementAt` implementations. A lazy
-  /// iterable with a lot of coordinate values may produce very poor
-  /// performance.
-  ///
   /// See [Position] for description about supported coordinate values.
   factory PositionSeries.view(
-    Iterable<double> source, {
+    List<double> source, {
     Coords type = Coords.xy,
   }) =>
       _PositionDataCoords.view(source, type: type);
@@ -81,27 +76,31 @@ abstract class PositionSeries implements Positionable {
   /// resolved from those positions (a type returned is such that it's valid
   /// for all positions).
   ///
-  /// An iterable collection of [source] may be represented by a [List] or any
-  /// [Iterable] with efficient `length` and `elementAt` implementations. A lazy
-  /// iterable with a lot of position objects may produce very poor performance.
+  /// If [source] is `List<Position>` then it's used directly as a source for a
+  /// new `PositionSeries` object. If [source] is `Iterable<Position>` then
+  /// items are iterated and copied to a list that is used as a source.
   ///
   /// See [Position] for description about supported coordinate values.
   factory PositionSeries.from(Iterable<Position> source, {Coords? type}) {
+    // ensure a list data structure
+    final data =
+        source is List<Position> ? source : source.toList(growable: false);
+
     if (type != null) {
-      return _PositionArray.view(source, type: type);
+      return _PositionArray.view(data, type: type);
     } else {
       var is3D = true;
       var isMeasured = true;
 
-      for (final elem in source) {
+      for (final elem in data) {
         final type = elem.type;
         is3D &= type.is3D;
         isMeasured &= type.isMeasured;
         if (!is3D && !isMeasured) break;
       }
 
       return _PositionArray.view(
-        source,
+        data,
         type: Coords.select(is3D: is3D, isMeasured: isMeasured),
       );
     }
@@ -384,6 +383,10 @@ class _PositionArray extends PositionSeries {
   final Coords _type;
 
   /// A series of positions with positions stored in [source].
+  ///
+  /// An iterable collection of [source] may be represented by a [List] or any
+  /// [Iterable] with efficient `length` and `elementAt` implementations. A lazy
+  /// iterable with a lot of position objects may produce very poor performance.
   const _PositionArray.view(
     Iterable<Position> source, {
     required Coords type,
@@ -508,6 +511,11 @@ class _PositionDataCoords extends PositionSeries {
   final Coords _type;
 
   /// A series of positions with coordinate values of [type] from [source].
+  ///
+  /// An iterable collection of [source] may be represented by a [List] or any
+  /// [Iterable] with efficient `length` and `elementAt` implementations. A lazy
+  /// iterable with a lot of coordinate values may produce very poor
+  /// performance.
   const _PositionDataCoords.view(
     Iterable<double> source, {
     Coords type = Coords.xy,

diff --git a/dart/geobase/lib/src/utils/coord_utils.dart b/dart/geobase/lib/src/utils/coord_utils.dart
@@ -11,7 +11,7 @@ import '/src/codes/coords.dart';
 /// A function to create an object of [T] from [coordinates] of [type].
 @internal
 typedef CreateAt<T> = T Function(
-  Iterable<double> coordinates, {
+  List<double> coordinates, {
   required Coords type,
 });
 
@@ -30,7 +30,7 @@ T doCreateRange<T>(
   if (coordinates is List<double>) {
     // the source coordinates is a List, get range
     return to.call(
-      coordinates.getRange(start, end),
+      coordinates.getRange(start, end).toList(growable: false),
       type: type,
     );
   } else {

diff --git a/dart/geobase/lib/src/vector_data/model/geometry/linestring.dart b/dart/geobase/lib/src/vector_data/model/geometry/linestring.dart
@@ -51,9 +51,7 @@ class LineString extends SimpleGeometry {
   /// The coordinate type of all positions in a chain should be the same.
   factory LineString.from(Iterable<Position> chain, {Box? bounds}) =>
       LineString(
-        PositionSeries.from(
-          chain is List<Position> ? chain : chain.toList(growable: false),
-        ),
+        PositionSeries.from(chain),
         bounds: bounds,
       );
 

diff --git a/dart/geobase/lib/src/vector_data/model/geometry/multi_linestring.dart b/dart/geobase/lib/src/vector_data/model/geometry/multi_linestring.dart
@@ -60,13 +60,7 @@ class MultiLineString extends SimpleGeometry {
     Box? bounds,
   }) =>
       MultiLineString(
-        lineStrings
-            .map(
-              (chain) => PositionSeries.from(
-                chain is List<Position> ? chain : chain.toList(growable: false),
-              ),
-            )
-            .toList(growable: false),
+        lineStrings.map(PositionSeries.from).toList(growable: false),
         bounds: bounds,
       );
 

diff --git a/dart/geobase/lib/src/vector_data/model/geometry/multi_polygon.dart b/dart/geobase/lib/src/vector_data/model/geometry/multi_polygon.dart
@@ -68,15 +68,8 @@ class MultiPolygon extends SimpleGeometry {
       MultiPolygon(
         polygons
             .map(
-              (polygon) => polygon
-                  .map(
-                    (ring) => PositionSeries.from(
-                      ring is List<Position>
-                          ? ring
-                          : ring.toList(growable: false),
-                    ),
-                  )
-                  .toList(growable: false),
+              (polygon) =>
+                  polygon.map(PositionSeries.from).toList(growable: false),
             )
             .toList(growable: false),
         bounds: bounds,

diff --git a/dart/geobase/lib/src/vector_data/model/geometry/polygon.dart b/dart/geobase/lib/src/vector_data/model/geometry/polygon.dart
@@ -72,13 +72,7 @@ class Polygon extends SimpleGeometry {
     Box? bounds,
   }) =>
       Polygon(
-        rings
-            .map(
-              (ring) => PositionSeries.from(
-                ring is List<Position> ? ring : ring.toList(growable: false),
-              ),
-            )
-            .toList(growable: false),
+        rings.map(PositionSeries.from).toList(growable: false),
         bounds: bounds,
       );
 

diff --git a/dart/geobase/test/coordinates/position_coords_test.dart b/dart/geobase/test/coordinates/position_coords_test.dart
@@ -257,7 +257,7 @@ void main() {
 
 void _testCoordinateOrder(
   String text,
-  Iterable<double> coords, [
+  List<double> coords, [
   Coords? type,
 ]) {
   final factories = [Position.create];

diff --git a/dart/geobase/test/coordinates/position_series_test.dart b/dart/geobase/test/coordinates/position_series_test.dart
@@ -171,8 +171,8 @@ void main() {
 
     test('Test equalsCoords', () {
       final iter = arr.map((e) => e * 10.0);
-      final xyIter2 = PositionSeries.view(iter);
-      final xyIter3 = PositionSeries.view(iter);
+      final xyIter2 = PositionSeries.view(iter.toList(growable: false));
+      final xyIter3 = PositionSeries.view(iter.toList(growable: false));
 
       expect(xy1.equalsCoords(xyIter2), false);
       expect(xyIter3.equalsCoords(xyIter2), true);