    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
    018    package org.apache.commons.math3.stat.clustering;
    019
    020    import java.io.Serializable;
    021    import java.util.Arrays;
    022    import java.util.Collection;
    023
    024    import org.apache.commons.math3.util.MathArrays;
    025
    026    /**
    027     * A simple implementation of {@link Clusterable} for points with integer coordinates.
    028     * @version $Id: EuclideanIntegerPoint.java 1416643 2012-12-03 19:37:14Z tn $
    029     * @since 2.0
    030     */
    031    public class EuclideanIntegerPoint implements Clusterable<EuclideanIntegerPoint>, Serializable {
    032
    033        /** Serializable version identifier. */
    034        private static final long serialVersionUID = 3946024775784901369L;
    035
    036        /** Point coordinates. */
    037        private final int[] point;
    038
    039        /**
    040         * Build an instance wrapping an integer array.
    041         * <p>The wrapped array is referenced, it is <em>not</em> copied.</p>
    042         * @param point the n-dimensional point in integer space
    043         */
    044        public EuclideanIntegerPoint(final int[] point) {
    045            this.point = point;
    046        }
    047
    048        /**
    049         * Get the n-dimensional point in integer space.
    050         * @return a reference (not a copy!) to the wrapped array
    051         */
    052        public int[] getPoint() {
    053            return point;
    054        }
    055
    056        /** {@inheritDoc} */
    057        public double distanceFrom(final EuclideanIntegerPoint p) {
    058            return MathArrays.distance(point, p.getPoint());
    059        }
    060
    061        /** {@inheritDoc} */
    062        public EuclideanIntegerPoint centroidOf(final Collection<EuclideanIntegerPoint> points) {
    063            int[] centroid = new int[getPoint().length];
    064            for (EuclideanIntegerPoint p : points) {
    065                for (int i = 0; i < centroid.length; i++) {
    066                    centroid[i] += p.getPoint()[i];
    067                }
    068            }
    069            for (int i = 0; i < centroid.length; i++) {
    070                centroid[i] /= points.size();
    071            }
    072            return new EuclideanIntegerPoint(centroid);
    073        }
    074
    075        /** {@inheritDoc} */
    076        @Override
    077        public boolean equals(final Object other) {
    078            if (!(other instanceof EuclideanIntegerPoint)) {
    079                return false;
    080            }
    081            return Arrays.equals(point, ((EuclideanIntegerPoint) other).point);
    082        }
    083
    084        /** {@inheritDoc} */
    085        @Override
    086        public int hashCode() {
    087            return Arrays.hashCode(point);
    088        }
    089
    090        /**
    091         * {@inheritDoc}
    092         * @since 2.1
    093         */
    094        @Override
    095        public String toString() {
    096            return Arrays.toString(point);
    097        }
    098
    099    }