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Java example source code file (ChineseRings.java)

This example Java source code file (ChineseRings.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

chineserings, realdistribution, rotation, uniformrealdistribution, unitsphererandomvectorgenerator, vector3d

The ChineseRings.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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package org.apache.commons.math3.userguide.sofm;

import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;
import org.apache.commons.math3.geometry.euclidean.threed.Rotation;
import org.apache.commons.math3.random.UnitSphereRandomVectorGenerator;
import org.apache.commons.math3.distribution.RealDistribution;
import org.apache.commons.math3.distribution.UniformRealDistribution;

 * Class that creates two intertwined rings.
 * Each ring is composed of a cloud of points.
public class ChineseRings {
    /** Points in the two rings. */
    private final Vector3D[] points;

     * @param orientationRing1 Vector othogonal to the plane containing the
     * first ring.
     * @param radiusRing1 Radius of the first ring.
     * @param halfWidthRing1 Half-width of the first ring.
     * @param radiusRing2 Radius of the second ring.
     * @param halfWidthRing2 Half-width of the second ring.
     * @param numPointsRing1 Number of points in the first ring.
     * @param numPointsRing2 Number of points in the second ring.
    public ChineseRings(Vector3D orientationRing1,
                        double radiusRing1,
                        double halfWidthRing1,
                        double radiusRing2,
                        double halfWidthRing2,
                        int numPointsRing1,
                        int numPointsRing2) {
        // First ring (centered at the origin).
        final Vector3D[] firstRing = new Vector3D[numPointsRing1];
        // Second ring (centered around the first ring).
        final Vector3D[] secondRing = new Vector3D[numPointsRing2];

        // Create two rings lying in xy-plane.
        final UnitSphereRandomVectorGenerator unit
            = new UnitSphereRandomVectorGenerator(2);

        final RealDistribution radius1
            = new UniformRealDistribution(radiusRing1 - halfWidthRing1,
                                          radiusRing1 + halfWidthRing1);
        final RealDistribution widthRing1
            = new UniformRealDistribution(-halfWidthRing1, halfWidthRing1);

        for (int i = 0; i < numPointsRing1; i++) {
            final double[] v = unit.nextVector();
            final double r = radius1.sample();
            // First ring is in the xy-plane, centered at (0, 0, 0).
            firstRing[i] = new Vector3D(v[0] * r,
                                        v[1] * r,

        final RealDistribution radius2
            = new UniformRealDistribution(radiusRing2 - halfWidthRing2,
                                          radiusRing2 + halfWidthRing2);
        final RealDistribution widthRing2
            = new UniformRealDistribution(-halfWidthRing2, halfWidthRing2);

        for (int i = 0; i < numPointsRing2; i++) {
            final double[] v = unit.nextVector();
            final double r = radius2.sample();
            // Second ring is in the xz-plane, centered at (radiusRing1, 0, 0).
            secondRing[i] = new Vector3D(radiusRing1 + v[0] * r,
                                         v[1] * r);

        // Move first and second rings into position.
        final Rotation rot = new Rotation(Vector3D.PLUS_K,
        int count = 0;
        points = new Vector3D[numPointsRing1 + numPointsRing2];
        for (int i = 0; i < numPointsRing1; i++) {
            points[count++] = rot.applyTo(firstRing[i]);
        for (int i = 0; i < numPointsRing2; i++) {
            points[count++] = rot.applyTo(secondRing[i]);

     * Gets all the points.
    public Vector3D[] getPoints() {
        return points.clone();

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