WelzlEncloser2DTest.java
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* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
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* https://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.commons.geometry.enclosing.euclidean.twod;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.commons.geometry.core.GeometryTestUtils;
import org.apache.commons.geometry.enclosing.EnclosingBall;
import org.apache.commons.geometry.euclidean.EuclideanTestUtils;
import org.apache.commons.geometry.euclidean.twod.Vector2D;
import org.apache.commons.numbers.core.Precision;
import org.apache.commons.rng.UniformRandomProvider;
import org.apache.commons.rng.simple.RandomSource;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
class WelzlEncloser2DTest {
private static final double TEST_EPS = 1e-10;
private static final Precision.DoubleEquivalence TEST_PRECISION =
Precision.doubleEquivalenceOfEpsilon(TEST_EPS);
private final WelzlEncloser2D encloser = new WelzlEncloser2D(TEST_PRECISION);
@Test
void testNoPoints() {
// arrange
final String msg = "Unable to generate enclosing ball: no points given";
// act/assert
GeometryTestUtils.assertThrowsWithMessage(() -> {
encloser.enclose(null);
}, IllegalArgumentException.class, msg);
GeometryTestUtils.assertThrowsWithMessage(() -> {
encloser.enclose(new ArrayList<Vector2D>());
}, IllegalArgumentException.class, msg);
}
@Test
void testRegularPoints() {
// arrange
final List<Vector2D> list = buildList(22, 26, 30, 38, 64, 28, 8, 54, 11, 15);
// act/assert
checkDisk(list, Arrays.asList(list.get(2), list.get(3), list.get(4)));
}
@Test
void testSolutionOnDiameter() {
// arrange
final List<Vector2D> list = buildList(22, 26, 30, 38, 64, 28, 8, 54);
// act/assert
checkDisk(list, Arrays.asList(list.get(2), list.get(3)));
}
@Test
void testReducingBall1() {
// arrange
final List<Vector2D> list = buildList(0.05380958511396061, 0.57332359658700000,
0.99348810731127870, 0.02056421361521466,
0.01203950647796437, 0.99779675042261860,
0.00810189987706078, 0.00589246003827815,
0.00465180821202149, 0.99219972923046940);
// act/assert
checkDisk(list, Arrays.asList(list.get(1), list.get(3), list.get(4)));
}
@Test
void testReducingBall2() {
// arrange
final List<Vector2D> list = buildList(0.016930586154703, 0.333955448537779,
0.987189104892331, 0.969778855274507,
0.983696889599935, 0.012904580013266,
0.013114499572905, 0.034740156356895);
// act/assert
checkDisk(list, Arrays.asList(list.get(1), list.get(2), list.get(3)));
}
@Test
void testLargeSamples() {
// arrange
final UniformRandomProvider random = RandomSource.XO_SHI_RO_256_PP.create(0xa2a63cad12c01fb2L);
for (int k = 0; k < 100; ++k) {
final int nbPoints = random.nextInt(10000);
final List<Vector2D> points = new ArrayList<>();
for (int i = 0; i < nbPoints; ++i) {
final double x = random.nextDouble();
final double y = random.nextDouble();
points.add(Vector2D.of(x, y));
}
// act/assert
checkDisk(points);
}
}
@Test
void testEnclosingWithPrecision() {
// arrange
final List<Vector2D> points = Arrays.asList(
Vector2D.of(271.59, 57.282),
Vector2D.of(269.145, 57.063),
Vector2D.of(309.117, 77.187),
Vector2D.of(316.989, 34.835),
Vector2D.of(323.101, 53.972)
);
final double precision = 1;
final Precision.DoubleEquivalence precisionContext = Precision.doubleEquivalenceOfEpsilon(precision);
final WelzlEncloser2D customPrecisionEncloser = new WelzlEncloser2D(precisionContext);
// act
final EnclosingBall<Vector2D> result = customPrecisionEncloser.enclose(points);
// assert
Assertions.assertEquals(27.099954200964234, result.getRadius(), TEST_EPS);
EuclideanTestUtils.assertCoordinatesEqual(Vector2D.of(296.0056977503686, 53.469890753441945),
result.getCenter(), TEST_EPS);
}
private List<Vector2D> buildList(final double... coordinates) {
final List<Vector2D> list = new ArrayList<>(coordinates.length / 2);
for (int i = 0; i < coordinates.length; i += 2) {
list.add(Vector2D.of(coordinates[i], coordinates[i + 1]));
}
return list;
}
private void checkDisk(final List<Vector2D> points, final List<Vector2D> refSupport) {
final EnclosingBall<Vector2D> disk = checkDisk(points);
// compare computed disk with expected disk
final EnclosingBall<Vector2D> expected = new DiskGenerator().ballOnSupport(refSupport);
Assertions.assertEquals(refSupport.size(), disk.getSupportSize());
Assertions.assertEquals(expected.getRadius(), disk.getRadius(), 1.0e-10);
Assertions.assertEquals(expected.getCenter().getX(), disk.getCenter().getX(), 1.0e-10);
Assertions.assertEquals(expected.getCenter().getY(), disk.getCenter().getY(), 1.0e-10);
for (final Vector2D s : disk.getSupport()) {
boolean found = false;
for (final Vector2D rs : refSupport) {
if (s == rs) {
found = true;
break;
}
}
Assertions.assertTrue(found);
}
// check removing any point of the support disk fails to enclose the point
for (int i = 0; i < disk.getSupportSize(); ++i) {
final List<Vector2D> reducedSupport = new ArrayList<>();
int count = 0;
for (final Vector2D s : disk.getSupport()) {
if (count++ != i) {
reducedSupport.add(s);
}
}
final EnclosingBall<Vector2D> reducedDisk = new DiskGenerator().ballOnSupport(reducedSupport);
boolean foundOutside = false;
for (int j = 0; j < points.size() && !foundOutside; ++j) {
if (!reducedDisk.contains(points.get(j), TEST_PRECISION)) {
foundOutside = true;
}
}
Assertions.assertTrue(foundOutside);
}
}
private EnclosingBall<Vector2D> checkDisk(final List<Vector2D> points) {
final EnclosingBall<Vector2D> disk = encloser.enclose(points);
// all points are enclosed
for (final Vector2D v : points) {
Assertions.assertTrue(disk.contains(v, TEST_PRECISION));
}
// all support points are on the boundary
final Vector2D center = disk.getCenter();
final double radius = disk.getRadius();
for (final Vector2D s : disk.getSupport()) {
Assertions.assertTrue(TEST_PRECISION.eqZero(center.distance(s) - radius));
}
return disk;
}
}