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.stat.descriptive.moment;
18
19 import java.util.Arrays;
20
21 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
22
23 /**
24 * Returns the arithmetic mean of the available vectors.
25 * @since 1.2
26 */
27 public class VectorialMean {
28 /** Means for each component. */
29 private final Mean[] means;
30
31 /** Constructs a VectorialMean.
32 * @param dimension vectors dimension
33 */
34 public VectorialMean(int dimension) {
35 means = new Mean[dimension];
36 for (int i = 0; i < dimension; ++i) {
37 means[i] = new Mean();
38 }
39 }
40
41 /**
42 * Add a new vector to the sample.
43 * @param v vector to add
44 * @throws DimensionMismatchException if the vector does not have the right dimension
45 */
46 public void increment(double[] v) throws DimensionMismatchException {
47 if (v.length != means.length) {
48 throw new DimensionMismatchException(v.length, means.length);
49 }
50 for (int i = 0; i < v.length; ++i) {
51 means[i].increment(v[i]);
52 }
53 }
54
55 /**
56 * Get the mean vector.
57 * @return mean vector
58 */
59 public double[] getResult() {
60 double[] result = new double[means.length];
61 for (int i = 0; i < result.length; ++i) {
62 result[i] = means[i].getResult();
63 }
64 return result;
65 }
66
67 /**
68 * Get the number of vectors in the sample.
69 * @return number of vectors in the sample
70 */
71 public long getN() {
72 return (means.length == 0) ? 0 : means[0].getN();
73 }
74
75 /** {@inheritDoc} */
76 @Override
77 public int hashCode() {
78 final int prime = 31;
79 int result = 1;
80 result = prime * result + Arrays.hashCode(means);
81 return result;
82 }
83
84 /** {@inheritDoc} */
85 @Override
86 public boolean equals(Object obj) {
87 if (this == obj) {
88 return true;
89 }
90 if (!(obj instanceof VectorialMean)) {
91 return false;
92 }
93 VectorialMean other = (VectorialMean) obj;
94 return Arrays.equals(means, other.means);
95 }
96 }