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 }