    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.math.stat.clustering;
    019
    020    import java.io.Serializable;
    021    import java.util.Collection;
    022
    023    import org.apache.commons.math.util.MathUtils;
    024
    025    /**
    026     * A simple implementation of {@link Clusterable} for points with integer coordinates.
    027     * @version $Revision: 1042376 $ $Date: 2010-12-05 16:54:55 +0100 (dim. 05 d??c. 2010) $
    028     * @since 2.0
    029     */
    030    public class EuclideanIntegerPoint implements Clusterable<EuclideanIntegerPoint>, Serializable {
    031
    032        /** Serializable version identifier. */
    033        private static final long serialVersionUID = 3946024775784901369L;
    034
    035        /** Point coordinates. */
    036        private final int[] point;
    037
    038        /**
    039         * Build an instance wrapping an integer array.
    040         * <p>The wrapped array is referenced, it is <em>not</em> copied.</p>
    041         * @param point the n-dimensional point in integer space
    042         */
    043        public EuclideanIntegerPoint(final int[] point) {
    044            this.point = point;
    045        }
    046
    047        /**
    048         * Get the n-dimensional point in integer space.
    049         * @return a reference (not a copy!) to the wrapped array
    050         */
    051        public int[] getPoint() {
    052            return point;
    053        }
    054
    055        /** {@inheritDoc} */
    056        public double distanceFrom(final EuclideanIntegerPoint p) {
    057            return MathUtils.distance(point, p.getPoint());
    058        }
    059
    060        /** {@inheritDoc} */
    061        public EuclideanIntegerPoint centroidOf(final Collection<EuclideanIntegerPoint> points) {
    062            int[] centroid = new int[getPoint().length];
    063            for (EuclideanIntegerPoint p : points) {
    064                for (int i = 0; i < centroid.length; i++) {
    065                    centroid[i] += p.getPoint()[i];
    066                }
    067            }
    068            for (int i = 0; i < centroid.length; i++) {
    069                centroid[i] /= points.size();
    070            }
    071            return new EuclideanIntegerPoint(centroid);
    072        }
    073
    074        /** {@inheritDoc} */
    075        @Override
    076        public boolean equals(final Object other) {
    077            if (!(other instanceof EuclideanIntegerPoint)) {
    078                return false;
    079            }
    080            final int[] otherPoint = ((EuclideanIntegerPoint) other).getPoint();
    081            if (point.length != otherPoint.length) {
    082                return false;
    083            }
    084            for (int i = 0; i < point.length; i++) {
    085                if (point[i] != otherPoint[i]) {
    086                    return false;
    087                }
    088            }
    089            return true;
    090        }
    091
    092        /** {@inheritDoc} */
    093        @Override
    094        public int hashCode() {
    095            int hashCode = 0;
    096            for (Integer i : point) {
    097                hashCode += i.hashCode() * 13 + 7;
    098            }
    099            return hashCode;
    100        }
    101
    102        /**
    103         * {@inheritDoc}
    104         * @since 2.1
    105         */
    106        @Override
    107        public String toString() {
    108            final StringBuilder buff = new StringBuilder("(");
    109            final int[] coordinates = getPoint();
    110            for (int i = 0; i < coordinates.length; i++) {
    111                buff.append(coordinates[i]);
    112                if (i < coordinates.length - 1) {
    113                    buff.append(",");
    114                }
    115            }
    116            buff.append(")");
    117            return buff.toString();
    118        }
    119
    120    }