1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.math.stat.clustering;
19
20 import java.io.Serializable;
21 import java.util.Collection;
22
23 import org.apache.commons.math.util.MathUtils;
24
25 /**
26 * A simple implementation of {@link Clusterable} for points with integer coordinates.
27 * @version $Revision: 795984 $ $Date: 2009-07-20 16:13:24 -0400 (Mon, 20 Jul 2009) $
28 * @since 2.0
29 */
30 public class EuclideanIntegerPoint implements Clusterable<EuclideanIntegerPoint>, Serializable {
31
32 /** Serializable version identifier. */
33 private static final long serialVersionUID = 3946024775784901369L;
34
35 /** Point coordinates. */
36 private final int[] point;
37
38 /**
39 * Build an instance wrapping an integer array.
40 * <p>The wrapped array is referenced, it is <em>not</em> copied.</p>
41 * @param point the n-dimensional point in integer space
42 */
43 public EuclideanIntegerPoint(final int[] point) {
44 this.point = point;
45 }
46
47 /**
48 * Get the n-dimensional point in integer space.
49 * @return a reference (not a copy!) to the wrapped array
50 */
51 public int[] getPoint() {
52 return point;
53 }
54
55 /** {@inheritDoc} */
56 public double distanceFrom(final EuclideanIntegerPoint p) {
57 return MathUtils.distance(point, p.getPoint());
58 }
59
60 /** {@inheritDoc} */
61 public EuclideanIntegerPoint centroidOf(final Collection<EuclideanIntegerPoint> points) {
62 int[] centroid = new int[getPoint().length];
63 for (EuclideanIntegerPoint p : points) {
64 for (int i = 0; i < centroid.length; i++) {
65 centroid[i] += p.getPoint()[i];
66 }
67 }
68 for (int i = 0; i < centroid.length; i++) {
69 centroid[i] /= points.size();
70 }
71 return new EuclideanIntegerPoint(centroid);
72 }
73
74 /** {@inheritDoc} */
75 @Override
76 public boolean equals(final Object other) {
77 if (!(other instanceof EuclideanIntegerPoint)) {
78 return false;
79 }
80 final int[] otherPoint = ((EuclideanIntegerPoint) other).getPoint();
81 if (point.length != otherPoint.length) {
82 return false;
83 }
84 for (int i = 0; i < point.length; i++) {
85 if (point[i] != otherPoint[i]) {
86 return false;
87 }
88 }
89 return true;
90 }
91
92 /** {@inheritDoc} */
93 @Override
94 public int hashCode() {
95 int hashCode = 0;
96 for (Integer i : point) {
97 hashCode += i.hashCode() * 13 + 7;
98 }
99 return hashCode;
100 }
101
102 }