1 package org.djutils.means;
2
3 /**
4 * Compute the geometric (weighted) mean of a set of values. Geometric mean can not handle negative or zero values.
5 * <p>
6 * Copyright (c) 2013-2016 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
7 * BSD-style license. See <a href="https://djutils.org/docs/current/djutils/licenses.html">DJUTILS License</a>.
8 * <p>
9 * @version $Revision$, $LastChangedDate$, by $Author$, initial version Oct 26, 2018 <br>
10 * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
11 * @author <a href="https://www.tudelft.nl/staff/p.knoppers/">Peter Knoppers</a>
12 * @param <V> value type
13 * @param <W> weight type
14 */
15 public class GeometricMean<V extends Number, W extends Number> extends AbstractMean<GeometricMean<V, W>, V, W>
16 {
17
18 /** {@inheritDoc} */
19 @Override
20 public final double getMean()
21 {
22 return Math.exp(getSum() / getSumOfWeights());
23 }
24
25 /** {@inheritDoc} */
26 @Override
27 public final GeometricMean<V, W> addImpl(final V value, final Number weight)
28 {
29 increment(Math.log(value.doubleValue()) * weight.doubleValue(), weight.doubleValue());
30 return this;
31 }
32
33 /** {@inheritDoc} */
34 @Override
35 public final String toString()
36 {
37 return "GeometricMean [current sum of logarithmic values=" + getSum() + ", current sum of weights=" + getSumOfWeights()
38 + ", current geometric mean=" + getMean() + "]";
39 }
40
41 }