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 }