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dzinaddzinad
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introduce TurfSimplify
1 parent 0b9f41b commit 30d7171

19 files changed

Lines changed: 825 additions & 2 deletions

‎CHANGELOG.md‎

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Mapbox welcomes participation and contributions from everyone.
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### main
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- Added `TurfSimplify#simplify` method to simplify `LineString` using Ramer-Douglas-Peucker algorithm. [1486](https://github.com/mapbox/mapbox-java/pull/1486)
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### v6.8.0-beta.3 - September 1, 2022
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- Added `subTypes` to `BannerComponents`. [#1485](https://github.com/mapbox/mapbox-java/pull/1485)

‎samples/build.gradle‎

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@@ -26,6 +26,7 @@ dependencies {
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implementation project(":services-tilequery")
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implementation project(":services-directions-refresh")
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implementation project(":services-isochrone")
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implementation project(":services-turf")
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}
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buildConfig {

‎samples/src/main/java/com/mapbox/samples/BasicTurfSimplify.java‎

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package com.mapbox.samples;
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import com.mapbox.api.directions.v5.DirectionsCriteria;
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import com.mapbox.api.directions.v5.models.DirectionsResponse;
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import com.mapbox.api.directions.v5.MapboxDirections;
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import com.mapbox.api.directions.v5.models.RouteOptions;
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import com.mapbox.core.constants.Constants;
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import com.mapbox.geojson.LineString;
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import com.mapbox.geojson.Point;
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import com.mapbox.sample.BuildConfig;
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import com.mapbox.turf.TurfSimplify;
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import retrofit2.Response;
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import java.io.IOException;
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import java.util.ArrayList;
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import java.util.List;
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public class BasicTurfSimplify {
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public static void main(String[] args) throws IOException {
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LineString complexLineString = generateLineString();
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LineString simplifiedLineString = LineString.fromLngLats(
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TurfSimplify.simplify(complexLineString.coordinates(), 0.001, true),
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complexLineString.bbox()
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);
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System.out.println("[Turf] complex: " + complexLineString.coordinates());
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System.out.println("[Turf] simplified: " + simplifiedLineString.coordinates());
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}
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private static LineString generateLineString() throws IOException {
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MapboxDirections.Builder builder = MapboxDirections.builder();
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// 1. Pass in all the required information to get a simple directions route.
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List<Point> coordinates = new ArrayList<>();
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coordinates.add(Point.fromLngLat(-95.6332, 29.7890));
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coordinates.add(Point.fromLngLat(-95.3591, 29.7576));
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RouteOptions routeOptions = RouteOptions.builder()
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.coordinatesList(coordinates)
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.profile(DirectionsCriteria.PROFILE_DRIVING_TRAFFIC)
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.build();
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builder.routeOptions(routeOptions);
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builder.accessToken(BuildConfig.MAPBOX_ACCESS_TOKEN);
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// 2. That's it! Now execute the command and get the response.
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Response<DirectionsResponse> response = builder.build().executeCall();
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return LineString.fromPolyline(response.body().routes().get(0).geometry(), Constants.PRECISION_6);
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}
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}

‎services-turf/src/main/java/com/mapbox/turf/TurfSimplify.java‎

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package com.mapbox.turf;
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import androidx.annotation.NonNull;
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import com.mapbox.geojson.Point;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* Use this class to simplify a complex line via Douglas-Peucker and radial algorithms.
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*/
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public class TurfSimplify {
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/**
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* Simplifies provided list of coordinates points into a shorter list of coordinates.
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*
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* @param original the coordinates to simplify
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* @param tolerance tolerance in the same measurement as the point coordinates
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* @param highQuality true for using Douglas-Peucker, false for Radial-Distance algorithm
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* @return simplified coordinates
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*/
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public static List<Point> simplify(
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@NonNull List<Point> original,
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double tolerance,
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boolean highQuality
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) {
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if (original.size() <= 2) {
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return original;
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}
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double squaredTolerance = tolerance * tolerance;
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List<Point> dpInput = highQuality ? original : simplifyRadial(original, squaredTolerance);
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return simplifyDouglasPeucker(dpInput, squaredTolerance);
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}
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private static List<Point> simplifyRadial(
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@NonNull List<Point> original,
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double squaredTolerance
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) {
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if (original.size() <= 2) {
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return original;
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}
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Point prevCoordinate = original.get(0);
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List<Point> newCoordinates = new ArrayList<>();
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newCoordinates.add(prevCoordinate);
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Point coordinate = original.get(1);
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for (int i = 1; i < original.size(); i++) {
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coordinate = original.get(i);
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if (squaredDistance(coordinate, prevCoordinate) > squaredTolerance) {
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newCoordinates.add(coordinate);
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prevCoordinate = coordinate;
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}
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}
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if (prevCoordinate != coordinate) {
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newCoordinates.add(coordinate);
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}
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return newCoordinates;
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}
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private static double squaredDistance(@NonNull Point p1, @NonNull Point p2) {
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double dx = p2.longitude() - p1.longitude();
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double dy = p2.latitude() - p1.latitude();
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return dx * dx + dy * dy;
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}
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private static List<Point> simplifyDouglasPeucker(
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@NonNull List<Point> original,
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double tolerance
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) {
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if (original.size() <= 2) {
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return original;
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}
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int lastPointIndex = original.size() - 1;
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List<Point> result = new ArrayList<>();
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result.add(original.get(0));
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simplifyDouglasPeuckerStep(original, 0, lastPointIndex, tolerance, result);
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result.add(original.get(lastPointIndex));
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return result;
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}
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private static void simplifyDouglasPeuckerStep(
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@NonNull List<Point> original,
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int startIndex,
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int endIndex,
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double tolerance,
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@NonNull List<Point> simplified
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) {
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double maxSquaredDistance = tolerance;
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int index = 0;
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for (int i = startIndex + 1; i < endIndex; i++) {
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double squaredDistance = squaredSegmentDistance(
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original.get(i),
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original.get(startIndex),
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original.get(endIndex)
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);
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if (squaredDistance > maxSquaredDistance) {
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index = i;
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maxSquaredDistance = squaredDistance;
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}
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}
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if (maxSquaredDistance > tolerance) {
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if (index - startIndex > 1) {
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simplifyDouglasPeuckerStep(original, startIndex, index, tolerance, simplified);
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}
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simplified.add(original.get(index));
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if (endIndex - index > 1) {
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simplifyDouglasPeuckerStep(original, index, endIndex, tolerance, simplified);
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}
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}
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}
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private static double squaredSegmentDistance(
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@NonNull Point point,
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@NonNull Point segmentStart,
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@NonNull Point segmentEnd
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) {
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double x = segmentStart.latitude();
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double y = segmentStart.longitude();
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double dx = segmentEnd.latitude() - x;
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double dy = segmentEnd.longitude() - y;
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if (dx != 0 || dy != 0) {
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double t = ((point.latitude() - x) * dx + (point.longitude() - y) * dy) / (dx * dx + dy * dy);
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if (t > 1) {
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x = segmentEnd.latitude();
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y = segmentEnd.longitude();
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} else if (t > 0) {
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x += dx * t;
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y += dy * t;
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}
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}
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dx = point.latitude() - x;
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dy = point.longitude() - y;
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return dx * dx + dy * dy;
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}
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}

‎services-turf/src/test/java/com/mapbox/turf/TestUtils.java‎

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@@ -33,12 +33,15 @@ public void compareJson(String expectedJson, String actualJson) {
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}
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protected String loadJsonFixture(String filename) {
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return readFile("src/test/resources/" + filename);
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}
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public String readFile(String filepath) {
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try {
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String filepath = "src/test/resources/" + filename;
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byte[] encoded = Files.readAllBytes(Paths.get(filepath));
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return new String(encoded, UTF_8);
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} catch (IOException e) {
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fail("Unable to load " + filename);
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fail("Unable to load " + filepath);
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return "";
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}
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}

‎services-turf/src/test/java/com/mapbox/turf/TurfSimplifySpecialCasesTest.java‎

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package com.mapbox.turf;
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import com.mapbox.geojson.Point;
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import org.junit.Test;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.List;
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import static org.junit.Assert.assertEquals;
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public class TurfSimplifySpecialCasesTest {
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@Test
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public void emptyCoordinates() {
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List<Point> input = new ArrayList<>();
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List<Point> output = TurfSimplify.simplify(input, 0.01, true);
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assertEquals(0, output.size());
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}
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@Test
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public void oneCoordinate() {
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List<Point> input = Collections.singletonList(Point.fromLngLat(1.0, 2.0));
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List<Point> output = TurfSimplify.simplify(input, 0.01, false);
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assertEquals(input, output);
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}
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@Test
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public void twoCoordinates() {
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List<Point> input = Arrays.asList(
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Point.fromLngLat(1.0, 2.0),
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Point.fromLngLat(-56.12, 87.09)
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);
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List<Point> output = TurfSimplify.simplify(input, 0.01, true);
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assertEquals(input, output);
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}
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}

‎services-turf/src/test/java/com/mapbox/turf/TurfSimplifyTest.java‎

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package com.mapbox.turf;
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import com.google.gson.JsonArray;
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import com.google.gson.JsonObject;
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import com.google.gson.JsonParser;
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import com.mapbox.geojson.Point;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.junit.runners.Parameterized;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.List;
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import java.util.stream.Collectors;
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import static org.junit.Assert.assertEquals;
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@RunWith(Parameterized.class)
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public class TurfSimplifyTest {
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@Parameterized.Parameters(name = "{0}")
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public static Collection<Object[]> data() {
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return new TestUtils().getResourceFolderFileNames("turf-simplify/input")
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.stream()
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.map(s -> new Object[] { s })
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.collect(Collectors.toList());
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}
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private final String fileName;
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private final TestUtils testUtils = new TestUtils();
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public TurfSimplifyTest(String fileName) {
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this.fileName = fileName;
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}
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@Test
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public void simplify() {
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String inputContent = testUtils.readFile("src/test/resources/turf-simplify/input/" + fileName);
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JsonObject json = JsonParser.parseString(inputContent).getAsJsonObject();
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JsonObject properties = json.getAsJsonObject("properties");
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double tolerance = properties.get("tolerance").getAsDouble();
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boolean highQuality = properties.get("highQuality").getAsBoolean();
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List<Point> input = parseCoordinates(json);
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String expectedContent = testUtils.readFile("src/test/resources/turf-simplify/output/" + fileName);
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List<Point> expected = parseCoordinates(JsonParser.parseString(expectedContent).getAsJsonObject());
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List<Point> output = TurfSimplify.simplify(input, tolerance, highQuality);
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checkPointsEquality(output, expected, 0.00001);
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}
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private List<Point> parseCoordinates(JsonObject json) {
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List<Point> points = new ArrayList<>();
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JsonArray jsonArray = json.getAsJsonArray("coordinates");
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for (int i = 0; i < jsonArray.size(); i++) {
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JsonArray coord = jsonArray.get(i).getAsJsonArray();
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double longitude = coord.get(0).getAsDouble();
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double latitude = coord.get(1).getAsDouble();
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points.add(Point.fromLngLat(longitude, latitude));
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}
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return points;
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}
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private void checkPointsEquality(List<Point> actual, List<Point> expected, double tolerance) {
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assertEquals(expected.size(), actual.size());
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for (int i = 0; i < expected.size(); i++) {
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assertEquals(expected.get(i).latitude(), actual.get(i).latitude(), tolerance);
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assertEquals(expected.get(i).longitude(), actual.get(i).longitude(), tolerance);
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}
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}
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}

‎services-turf/src/test/resources/turf-simplify/input/set1.json‎

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{
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"properties": {
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"tolerance": 0.01,
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"highQuality": false
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},
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"coordinates": [
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[27.977542877197266, -26.17500493262446],
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[27.975482940673828, -26.17870225771557],
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[27.969818115234375, -26.177931991326645],
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[27.967071533203125, -26.177623883345735],
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[27.966899871826172, -26.1810130263384],
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[27.967758178710938, -26.1853263385099],
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[27.97290802001953, -26.1853263385099],
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[27.97496795654297, -26.18270756087535],
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[27.97840118408203, -26.1810130263384],
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[27.98011779785156, -26.183323749143113],
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[27.98011779785156, -26.18655868408986],
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[27.978744506835938, -26.18933141398614],
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[27.97496795654297, -26.19025564262006],
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[27.97119140625, -26.19040968001282],
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[27.969303131103516, -26.1899475672235],
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[27.96741485595703, -26.189639491012183],
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[27.9656982421875, -26.187945057286793],
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[27.965354919433594, -26.18563442612686],
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[27.96432495117187, -26.183015655416536]
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]
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}

‎services-turf/src/test/resources/turf-simplify/input/set1_high_precision.json‎

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{
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"properties": {
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"tolerance": 0.0001,
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"highQuality": false
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},
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"coordinates": [
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[27.977542877197266, -26.17500493262446],
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[27.975482940673828, -26.17870225771557],
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[27.969818115234375, -26.177931991326645],
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[27.967071533203125, -26.177623883345735],
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[27.966899871826172, -26.1810130263384],
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[27.967758178710938, -26.1853263385099],
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[27.97290802001953, -26.1853263385099],
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[27.97496795654297, -26.18270756087535],
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[27.97840118408203, -26.1810130263384],
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[27.98011779785156, -26.183323749143113],
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[27.98011779785156, -26.18655868408986],
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[27.978744506835938, -26.18933141398614],
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[27.97496795654297, -26.19025564262006],
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[27.97119140625, -26.19040968001282],
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[27.969303131103516, -26.1899475672235],
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[27.96741485595703, -26.189639491012183],
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[27.9656982421875, -26.187945057286793],
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[27.965354919433594, -26.18563442612686],
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[27.96432495117187, -26.183015655416536]
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]
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}

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