    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.math3.stat.clustering;
    018
    019    import java.io.Serializable;
    020    import java.util.Collection;
    021    import java.util.Arrays;
    022
    023    import org.apache.commons.math3.util.MathArrays;
    024
    025    /**
    026     * A simple implementation of {@link Clusterable} for points with double coordinates.
    027     * @version $Id: EuclideanDoublePoint.java 1413096 2012-11-23 22:34:05Z erans $
    028     * @since 3.1
    029     */
    030    public class EuclideanDoublePoint implements Clusterable<EuclideanDoublePoint>, Serializable {
    031
    032        /** Serializable version identifier. */
    033        private static final long serialVersionUID = 8026472786091227632L;
    034
    035        /** Point coordinates. */
    036        private final double[] point;
    037
    038        /**
    039         * Build an instance wrapping an integer array.
    040         * <p>
    041         * The wrapped array is referenced, it is <em>not</em> copied.
    042         *
    043         * @param point the n-dimensional point in integer space
    044         */
    045        public EuclideanDoublePoint(final double[] point) {
    046            this.point = point;
    047        }
    048
    049        /** {@inheritDoc} */
    050        public EuclideanDoublePoint centroidOf(final Collection<EuclideanDoublePoint> points) {
    051            final double[] centroid = new double[getPoint().length];
    052            for (final EuclideanDoublePoint p : points) {
    053                for (int i = 0; i < centroid.length; i++) {
    054                    centroid[i] += p.getPoint()[i];
    055                }
    056            }
    057            for (int i = 0; i < centroid.length; i++) {
    058                centroid[i] /= points.size();
    059            }
    060            return new EuclideanDoublePoint(centroid);
    061        }
    062
    063        /** {@inheritDoc} */
    064        public double distanceFrom(final EuclideanDoublePoint p) {
    065            return MathArrays.distance(point, p.getPoint());
    066        }
    067
    068        /** {@inheritDoc} */
    069        @Override
    070        public boolean equals(final Object other) {
    071            if (!(other instanceof EuclideanDoublePoint)) {
    072                return false;
    073            }
    074            return Arrays.equals(point, ((EuclideanDoublePoint) other).point);
    075        }
    076
    077        /**
    078         * Get the n-dimensional point in integer space.
    079         *
    080         * @return a reference (not a copy!) to the wrapped array
    081         */
    082        public double[] getPoint() {
    083            return point;
    084        }
    085
    086        /** {@inheritDoc} */
    087        @Override
    088        public int hashCode() {
    089            return Arrays.hashCode(point);
    090        }
    091
    092        /** {@inheritDoc} */
    093        @Override
    094        public String toString() {
    095            return Arrays.toString(point);
    096        }
    097
    098    }