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Andy2003Andy2003
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Add a spatial function to convert WKT to Geo-JSON (#406)
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‎src/main/java/org/neo4j/gis/spatial/functions/SpatialFunctions.java‎

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package org.neo4j.gis.spatial.functions;
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import org.locationtech.jts.geom.Geometry;
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import org.locationtech.jts.io.ParseException;
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import org.locationtech.jts.io.WKTReader;
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import org.neo4j.gis.spatial.Layer;
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import org.neo4j.gis.spatial.procedures.SpatialProcedures.GeometryResult;
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import org.neo4j.gis.spatial.utilities.GeoJsonUtils;
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import org.neo4j.gis.spatial.utilities.SpatialApiBase;
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import org.neo4j.graphdb.Node;
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import org.neo4j.procedure.Description;
@@ -55,4 +59,14 @@ public Object asGeometry(@Name("geometry") Object geometry) {
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}
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@UserFunction("spatial.wktToGeoJson")
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@Description("Converts a WKT to GeoJson structure")
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public Object wktToGeoJson(@Name("wkt") String wkt) throws ParseException {
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if (wkt == null) {
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return null;
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}
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WKTReader wktReader = new WKTReader();
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Geometry geometry = wktReader.read(wkt);
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return GeoJsonUtils.toGeoJsonStructure(geometry);
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}
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}

‎src/main/java/org/neo4j/gis/spatial/utilities/GeoJsonUtils.java‎

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/*
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* Copyright (c) "Neo4j"
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* Neo4j Sweden AB [http://neo4j.com]
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*
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* This file is part of Neo4j Spatial.
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*
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* Neo4j is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.neo4j.gis.spatial.utilities;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Map;
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import java.util.stream.IntStream;
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import java.util.stream.Stream;
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import org.locationtech.jts.geom.Coordinate;
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import org.locationtech.jts.geom.Geometry;
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import org.locationtech.jts.geom.GeometryCollection;
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import org.locationtech.jts.geom.LineString;
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import org.locationtech.jts.geom.Point;
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import org.locationtech.jts.geom.Polygon;
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public class GeoJsonUtils {
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private GeoJsonUtils() {
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}
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public static Map<String, Object> toGeoJsonStructure(Geometry geometry) {
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if (geometry instanceof GeometryCollection geometryCollection && "GeometryCollection".equals(
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geometry.getGeometryType())) {
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return Map.of(
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"type", geometry.getGeometryType(),
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"geometries", IntStream.range(0, geometryCollection.getNumGeometries())
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.mapToObj(geometryCollection::getGeometryN)
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.map(GeoJsonUtils::toGeoJsonStructure)
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.toList()
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);
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}
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return Map.of(
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"type", geometry.getGeometryType(),
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"coordinates", getCoordinates(geometry)
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);
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}
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private static List<?> getCoordinates(Geometry geometry) {
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if (geometry instanceof Point point) {
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return getPoint(point.getCoordinate());
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}
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if (geometry instanceof LineString lineString) {
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return Arrays.stream(lineString.getCoordinates()).map(GeoJsonUtils::getPoint).toList();
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}
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if (geometry instanceof Polygon polygon) {
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return Stream.concat(
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Stream.of(polygon.getExteriorRing()),
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IntStream.range(0, polygon.getNumInteriorRing())
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.mapToObj(polygon::getInteriorRingN)
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)
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.map(GeoJsonUtils::getCoordinates)
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.toList();
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}
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if (geometry instanceof GeometryCollection geometryCollection) {
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return IntStream.range(0, geometryCollection.getNumGeometries())
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.mapToObj(geometryCollection::getGeometryN)
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.map(GeoJsonUtils::getCoordinates)
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.toList();
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}
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throw new IllegalArgumentException("Unsupported geometry type: " + geometry.getGeometryType());
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}
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private static List<Object> getPoint(Coordinate coordinate) {
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if (Double.isNaN(coordinate.getZ())) {
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return List.of(coordinate.getX(), coordinate.getY());
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}
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return List.of(
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coordinate.getX(),
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coordinate.getY(),
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coordinate.getZ());
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}
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}

‎src/test/java/org/neo4j/gis/spatial/functions/SpatialFunctionsTest.java‎

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package org.neo4j.gis.spatial.functions;
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import static org.hamcrest.MatcherAssert.assertThat;
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import static org.hamcrest.Matchers.closeTo;
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import static org.hamcrest.Matchers.equalTo;
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import static org.junit.jupiter.api.Assertions.assertInstanceOf;
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import java.util.List;
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import java.util.Map;
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import org.hamcrest.MatcherAssert;
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import org.junit.jupiter.api.Nested;
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import org.junit.jupiter.api.Test;
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import org.neo4j.exceptions.KernelException;
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import org.neo4j.gis.spatial.AbstractApiTest;
@@ -69,4 +73,242 @@ public void literal_geometry_return() {
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"WITH spatial.asGeometry({latitude: 5.0, longitude: 4.0}) AS geometry RETURN geometry", "geometry");
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assertInstanceOf(Geometry.class, geometry, "Should be Geometry type");
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}
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/**
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* Test for all WKT types
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*
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* @see <a href="https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry">Wikipedia WKT</a>
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*/
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@Nested
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class WktToGeoJson {
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@Test
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public void testPoint() {
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String wkt = "POINT (30 10)";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "Point",
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"coordinates", List.of(30., 10.)
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)));
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}
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@Test
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public void testLineString() {
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String wkt = "LINESTRING (30 10, 10 30, 40 40)";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "LineString",
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"coordinates", List.of(List.of(30., 10.), List.of(10., 30.), List.of(40., 40.))
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)));
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}
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@Test
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public void testPolygon() {
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String wkt = "POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "Polygon",
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"coordinates",
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List.of( // Polygon
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List.of( // LineString
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List.of(30., 10.),
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List.of(40., 40.),
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List.of(20., 40.),
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List.of(10., 20.),
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List.of(30., 10.)
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)
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)
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)));
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}
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@Test
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public void testPolygonWithHole() {
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String wkt = "POLYGON ((35 10, 45 45, 15 40, 10 20, 35 10),\n"
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+ "(20 30, 35 35, 30 20, 20 30))";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "Polygon",
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"coordinates",
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List.of( // Polygon
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List.of( // LineString
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List.of(35., 10.),
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List.of(45., 45.),
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List.of(15., 40.),
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List.of(10., 20.),
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List.of(35., 10.)
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),
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List.of( // hole
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List.of(20., 30.),
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List.of(35., 35.),
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List.of(30., 20.),
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List.of(20., 30.)
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)
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)
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)));
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}
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@Test
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public void testMultiPoint() {
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String wkt = "MULTIPOINT ((10 40), (40 30), (20 20), (30 10))";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "MultiPoint",
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"coordinates", List.of(
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List.of(10., 40.),
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List.of(40., 30.),
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List.of(20., 20.),
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List.of(30., 10.)
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))));
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}
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@Test
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public void testMultiPoint2() {
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String wkt = "MULTIPOINT (10 40, 40 30, 20 20, 30 10)";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "MultiPoint",
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"coordinates", List.of(
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List.of(10., 40.),
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List.of(40., 30.),
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List.of(20., 20.),
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List.of(30., 10.)
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))));
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}
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@Test
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public void testMultiLineString() {
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String wkt = "MULTILINESTRING ((10 10, 20 20, 10 40),\n"
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+ "(40 40, 30 30, 40 20, 30 10))";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "MultiLineString",
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"coordinates", List.of(
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List.of( // LineString
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List.of(10., 10.),
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List.of(20., 20.),
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List.of(10., 40.)
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),
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List.of( // LineString
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List.of(40., 40.),
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List.of(30., 30.),
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List.of(40., 20.),
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List.of(30., 10.)
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)
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))));
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}
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@Test
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public void testMultiPolygon() {
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String wkt = "MULTIPOLYGON (((30 20, 45 40, 10 40, 30 20)),\n"
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+ "((15 5, 40 10, 10 20, 5 10, 15 5)))";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "MultiPolygon",
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"coordinates", List.of( // MultiPolygon
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List.of( // Polygon
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List.of( // LineString
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List.of(30., 20.),
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List.of(45., 40.),
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List.of(10., 40.),
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List.of(30., 20.)
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)
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),
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List.of( // Polygon
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List.of( // LineString
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List.of(15., 5.),
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List.of(40., 10.),
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List.of(10., 20.),
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List.of(5., 10.),
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List.of(15., 5.)
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)
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)
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)
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)));
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}
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@Test
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public void testMultiPolygon2() {
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String wkt = """
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MULTIPOLYGON (((40 40, 20 45, 45 30, 40 40)),
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((20 35, 10 30, 10 10, 30 5, 45 20, 20 35),
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(30 20, 20 15, 20 25, 30 20)))""";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "MultiPolygon",
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"coordinates", List.of( // MultiPolygon
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List.of( // Polygon
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List.of( // LineString
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List.of(40., 40.),
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List.of(20., 45.),
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List.of(45., 30.),
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List.of(40., 40.)
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)
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),
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List.of( // Polygon
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List.of( // LineString
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List.of(20., 35.),
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List.of(10., 30.),
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List.of(10., 10.),
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List.of(30., 5.),
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List.of(45., 20.),
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List.of(20., 35.)
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),
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List.of( // hole
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List.of(30., 20.),
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List.of(20., 15.),
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List.of(20., 25.),
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List.of(30., 20.)
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)
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)
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)
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)));
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}
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@Test
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public void testGeometryCollection() {
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String wkt = """
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GEOMETRYCOLLECTION (POINT (40 10),
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LINESTRING (10 10, 20 20, 10 40),
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POLYGON ((40 40, 20 45, 45 30, 40 40)))""";
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Object json = executeObject("return spatial.wktToGeoJson($wkt) as json", Map.of("wkt", wkt),
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"json");
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assertThat(json, equalTo(Map.of(
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"type", "GeometryCollection",
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"geometries", List.of(
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Map.of( // Point
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"type", "Point",
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"coordinates", List.of(40., 10.)
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),
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Map.of( // LineString
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"type", "LineString",
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"coordinates", List.of(
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List.of(10., 10.),
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List.of(20., 20.),
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List.of(10., 40.)
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)
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),
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Map.of( // Polygon
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"type", "Polygon",
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"coordinates", List.of(
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List.of( // LineString
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List.of(40., 40.),
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List.of(20., 45.),
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List.of(45., 30.),
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List.of(40., 40.)
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)
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)
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)
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)
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)));
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}
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}
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}

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