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 * @version $Id: VectorialMean.java 1416643 2012-12-03 19:37:14Z tn $
028 */
029public class VectorialMean implements Serializable {
030
031    /** Serializable version identifier */
032    private static final long serialVersionUID = 8223009086481006892L;
033
034    /** Means for each component. */
035    private final Mean[] means;
036
037    /** Constructs a VectorialMean.
038     * @param dimension vectors dimension
039     */
040    public VectorialMean(int dimension) {
041        means = new Mean[dimension];
042        for (int i = 0; i < dimension; ++i) {
043            means[i] = new Mean();
044        }
045    }
046
047    /**
048     * Add a new vector to the sample.
049     * @param v vector to add
050     * @throws DimensionMismatchException if the vector does not have the right dimension
051     */
052    public void increment(double[] v) throws DimensionMismatchException {
053        if (v.length != means.length) {
054            throw new DimensionMismatchException(v.length, means.length);
055        }
056        for (int i = 0; i < v.length; ++i) {
057            means[i].increment(v[i]);
058        }
059    }
060
061    /**
062     * Get the mean vector.
063     * @return mean vector
064     */
065    public double[] getResult() {
066        double[] result = new double[means.length];
067        for (int i = 0; i < result.length; ++i) {
068            result[i] = means[i].getResult();
069        }
070        return result;
071    }
072
073    /**
074     * Get the number of vectors in the sample.
075     * @return number of vectors in the sample
076     */
077    public long getN() {
078        return (means.length == 0) ? 0 : means[0].getN();
079    }
080
081    /** {@inheritDoc} */
082    @Override
083    public int hashCode() {
084        final int prime = 31;
085        int result = 1;
086        result = prime * result + Arrays.hashCode(means);
087        return result;
088    }
089
090    /** {@inheritDoc} */
091    @Override
092    public boolean equals(Object obj) {
093        if (this == obj) {
094            return true;
095        }
096        if (!(obj instanceof VectorialMean)) {
097            return false;
098        }
099        VectorialMean other = (VectorialMean) obj;
100        if (!Arrays.equals(means, other.means)) {
101            return false;
102        }
103        return true;
104    }
105
106}