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 }