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.math.stat.descriptive.moment;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.math.DimensionMismatchException;
22
23 /**
24 * Returns the arithmetic mean of the available vectors.
25 * @since 1.2
26 * @version $Revision: 619928 $ $Date: 2008-02-08 09:19:17 -0700 (Fri, 08 Feb 2008) $
27 */
28 public class VectorialMean implements Serializable {
29
30 /** Serializable version identifier */
31 private static final long serialVersionUID = 8223009086481006892L;
32
33 /** Means for each component. */
34 private Mean[] means;
35
36 /** Constructs a VectorialMean.
37 * @param dimension vectors dimension
38 */
39 public VectorialMean(int dimension) {
40 means = new Mean[dimension];
41 for (int i = 0; i < dimension; ++i) {
42 means[i] = new Mean();
43 }
44 }
45
46 /**
47 * Add a new vector to the sample.
48 * @param v vector to add
49 * @exception DimensionMismatchException if the vector does not have the right dimension
50 */
51 public void increment(double[] v) throws DimensionMismatchException {
52 if (v.length != means.length) {
53 throw new DimensionMismatchException(v.length, means.length);
54 }
55 for (int i = 0; i < v.length; ++i) {
56 means[i].increment(v[i]);
57 }
58 }
59
60 /**
61 * Get the mean vector.
62 * @return mean vector
63 */
64 public double[] getResult() {
65 double[] result = new double[means.length];
66 for (int i = 0; i < result.length; ++i) {
67 result[i] = means[i].getResult();
68 }
69 return result;
70 }
71
72 /**
73 * Get the number of vectors in the sample.
74 * @return number of vectors in the sample
75 */
76 public long getN() {
77 return (means.length == 0) ? 0 : means[0].getN();
78 }
79
80 }