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Java example source code file (WelzlEncloser2DTest.java)

This example Java source code file (WelzlEncloser2DTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, diskgenerator, enclosingball, list, randomgenerator, test, util, vector2d, well1024a, welzlencloser, welzlencloser2dtest

The WelzlEncloser2DTest.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * 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
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math3.geometry.enclosing;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.math3.geometry.euclidean.twod.DiskGenerator;
import org.apache.commons.math3.geometry.euclidean.twod.Euclidean2D;
import org.apache.commons.math3.geometry.euclidean.twod.Vector2D;
import org.apache.commons.math3.random.RandomGenerator;
import org.apache.commons.math3.random.Well1024a;
import org.junit.Assert;
import org.junit.Test;


public class WelzlEncloser2DTest {

    @Test
    public void testNullList() {
        DiskGenerator generator = new DiskGenerator();
        WelzlEncloser<Euclidean2D, Vector2D> encloser =
                new WelzlEncloser<Euclidean2D, Vector2D>(1.0e-10, generator);
        EnclosingBall<Euclidean2D, Vector2D> ball = encloser.enclose(null);
        Assert.assertTrue(ball.getRadius() < 0);
    }

    @Test
    public void testNoPoints() {
        DiskGenerator generator = new DiskGenerator();
        WelzlEncloser<Euclidean2D, Vector2D> encloser =
                new WelzlEncloser<Euclidean2D, Vector2D>(1.0e-10, generator);
        EnclosingBall<Euclidean2D, Vector2D> ball = encloser.enclose(new ArrayList());
        Assert.assertTrue(ball.getRadius() < 0);
    }

    @Test
    public void testRegularPoints() {
        List<Vector2D> list = buildList(22, 26, 30, 38, 64, 28,  8, 54, 11, 15);
        checkDisk(list, Arrays.asList(list.get(2), list.get(3), list.get(4)));
    }

    @Test
    public void testSolutionOnDiameter() {
        List<Vector2D> list = buildList(22, 26, 30, 38, 64, 28,  8, 54);
        checkDisk(list, Arrays.asList(list.get(2), list.get(3)));
    }

    @Test
    public void testReducingBall1() {
        List<Vector2D> list = buildList(0.05380958511396061, 0.57332359658700000,
                                        0.99348810731127870, 0.02056421361521466,
                                        0.01203950647796437, 0.99779675042261860,
                                        0.00810189987706078, 0.00589246003827815,
                                        0.00465180821202149, 0.99219972923046940);
        checkDisk(list, Arrays.asList(list.get(1), list.get(3), list.get(4)));
    }

    @Test
    public void testReducingBall2() {
        List<Vector2D> list = buildList(0.016930586154703, 0.333955448537779,
                                        0.987189104892331, 0.969778855274507,
                                        0.983696889599935, 0.012904580013266,
                                        0.013114499572905, 0.034740156356895);
        checkDisk(list, Arrays.asList(list.get(1), list.get(2), list.get(3)));
    }

    @Test
    public void testLargeSamples() {
        RandomGenerator random = new Well1024a(0xa2a63cad12c01fb2l);
        for (int k = 0; k < 100; ++k) {
            int nbPoints = random.nextInt(10000);
            List<Vector2D> points = new ArrayList();
            for (int i = 0; i < nbPoints; ++i) {
                double x = random.nextDouble();
                double y = random.nextDouble();
                points.add(new Vector2D(x, y));
            }
            checkDisk(points);
        }
    }

    private List<Vector2D> buildList(final double ... coordinates) {
        List<Vector2D> list = new ArrayList(coordinates.length / 2);
        for (int i = 0; i < coordinates.length; i += 2) {
            list.add(new Vector2D(coordinates[i], coordinates[i + 1]));
        }
        return list;
    }

    private void checkDisk(List<Vector2D> points, List refSupport) {

        EnclosingBall<Euclidean2D, Vector2D> disk = checkDisk(points);

        // compare computed disk with expected disk
        DiskGenerator generator = new DiskGenerator();
        EnclosingBall<Euclidean2D, Vector2D> expected = generator.ballOnSupport(refSupport);
        Assert.assertEquals(refSupport.size(), disk.getSupportSize());
        Assert.assertEquals(expected.getRadius(),        disk.getRadius(),        1.0e-10);
        Assert.assertEquals(expected.getCenter().getX(), disk.getCenter().getX(), 1.0e-10);
        Assert.assertEquals(expected.getCenter().getY(), disk.getCenter().getY(), 1.0e-10);

        for (Vector2D s : disk.getSupport()) {
            boolean found = false;
            for (Vector2D rs : refSupport) {
                if (s == rs) {
                    found = true;
                }
            }
            Assert.assertTrue(found);
        }

        // check removing any point of the support disk fails to enclose the point
        for (int i = 0; i < disk.getSupportSize(); ++i) {
            List<Vector2D> reducedSupport = new ArrayList();
            int count = 0;
            for (Vector2D s : disk.getSupport()) {
                if (count++ != i) {
                    reducedSupport.add(s);
                }
            }
            EnclosingBall<Euclidean2D, Vector2D> reducedDisk = generator.ballOnSupport(reducedSupport);
            boolean foundOutside = false;
            for (int j = 0; j < points.size() && !foundOutside; ++j) {
                if (!reducedDisk.contains(points.get(j), 1.0e-10)) {
                    foundOutside = true;
                }
            }
            Assert.assertTrue(foundOutside);
        }

    }

    private EnclosingBall<Euclidean2D, Vector2D> checkDisk(List points) {

        WelzlEncloser<Euclidean2D, Vector2D> encloser =
                new WelzlEncloser<Euclidean2D, Vector2D>(1.0e-10, new DiskGenerator());
        EnclosingBall<Euclidean2D, Vector2D> disk = encloser.enclose(points);

        // all points are enclosed
        for (Vector2D v : points) {
            Assert.assertTrue(disk.contains(v, 1.0e-10));
        }

        for (Vector2D v : points) {
            boolean inSupport = false;
            for (Vector2D s : disk.getSupport()) {
                if (v == s) {
                    inSupport = true;
                }
            }
            if (inSupport) {
                // points on the support should be outside of reduced ball
                Assert.assertFalse(disk.contains(v, -0.001));
            }
        }

        return disk;

    }

}

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