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 */ 017package org.apache.commons.math3.stat.descriptive.moment; 018 019import java.io.Serializable; 020import java.util.Arrays; 021 022import org.apache.commons.math3.exception.DimensionMismatchException; 023 024/** 025 * Returns the arithmetic mean of the available vectors. 026 * @since 1.2 027 */ 028public class VectorialMean implements Serializable { 029 030 /** Serializable version identifier */ 031 private static final long serialVersionUID = 8223009086481006892L; 032 033 /** Means for each component. */ 034 private final Mean[] means; 035 036 /** Constructs a VectorialMean. 037 * @param dimension vectors dimension 038 */ 039 public VectorialMean(int dimension) { 040 means = new Mean[dimension]; 041 for (int i = 0; i < dimension; ++i) { 042 means[i] = new Mean(); 043 } 044 } 045 046 /** 047 * Add a new vector to the sample. 048 * @param v vector to add 049 * @throws DimensionMismatchException if the vector does not have the right dimension 050 */ 051 public void increment(double[] v) throws DimensionMismatchException { 052 if (v.length != means.length) { 053 throw new DimensionMismatchException(v.length, means.length); 054 } 055 for (int i = 0; i < v.length; ++i) { 056 means[i].increment(v[i]); 057 } 058 } 059 060 /** 061 * Get the mean vector. 062 * @return mean vector 063 */ 064 public double[] getResult() { 065 double[] result = new double[means.length]; 066 for (int i = 0; i < result.length; ++i) { 067 result[i] = means[i].getResult(); 068 } 069 return result; 070 } 071 072 /** 073 * Get the number of vectors in the sample. 074 * @return number of vectors in the sample 075 */ 076 public long getN() { 077 return (means.length == 0) ? 0 : means[0].getN(); 078 } 079 080 /** {@inheritDoc} */ 081 @Override 082 public int hashCode() { 083 final int prime = 31; 084 int result = 1; 085 result = prime * result + Arrays.hashCode(means); 086 return result; 087 } 088 089 /** {@inheritDoc} */ 090 @Override 091 public boolean equals(Object obj) { 092 if (this == obj) { 093 return true; 094 } 095 if (!(obj instanceof VectorialMean)) { 096 return false; 097 } 098 VectorialMean other = (VectorialMean) obj; 099 if (!Arrays.equals(means, other.means)) { 100 return false; 101 } 102 return true; 103 } 104 105}