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 package org.apache.commons.math4.legacy.ml.clustering;
18
19 import java.util.Collection;
20 import java.util.List;
21
22 import org.apache.commons.math4.legacy.ml.distance.DistanceMeasure;
23
24 /**
25 * Base class for clustering algorithms.
26 *
27 * @param <T> the type of points that can be clustered
28 * @since 3.2
29 */
30 public abstract class Clusterer<T extends Clusterable> {
31
32 /** The distance measure to use. */
33 private DistanceMeasure measure;
34
35 /**
36 * Build a new clusterer with the given {@link DistanceMeasure}.
37 *
38 * @param measure the distance measure to use
39 */
40 protected Clusterer(final DistanceMeasure measure) {
41 this.measure = measure;
42 }
43
44 /**
45 * Perform a cluster analysis on the given set of {@link Clusterable} instances.
46 *
47 * @param points the set of {@link Clusterable} instances
48 * @return a {@link List} of clusters
49 * @throws IllegalArgumentException if points are null or the number of
50 * data points is not compatible with this clusterer.
51 * @throws org.apache.commons.math4.legacy.exception.ConvergenceException
52 * if the algorithm has not yet converged after the maximum number of
53 * iterations has been exceeded.
54 */
55 public abstract List<? extends Cluster<T>> cluster(Collection<T> points);
56
57 /**
58 * Returns the {@link DistanceMeasure} instance used by this clusterer.
59 *
60 * @return the distance measure
61 */
62 public DistanceMeasure getDistanceMeasure() {
63 return measure;
64 }
65
66 /**
67 * Calculates the distance between two {@link Clusterable} instances
68 * with the configured {@link DistanceMeasure}.
69 *
70 * @param p1 the first clusterable
71 * @param p2 the second clusterable
72 * @return the distance between the two clusterables
73 */
74 protected double distance(final Clusterable p1, final Clusterable p2) {
75 return measure.compute(p1.getPoint(), p2.getPoint());
76 }
77 }