Dave Hoover
02899d1083
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6407 542714f4-19e9-0310-aa3c-eee0fc999fb1
94 lines
2.5 KiB
Java
94 lines
2.5 KiB
Java
//
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// $Id$
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//
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// Narya library - tools for developing networked games
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// Copyright (C) 2002-2011 Three Rings Design, Inc., All Rights Reserved
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// http://code.google.com/p/narya/
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package com.threerings.util;
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/**
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* Calculates live values for the mean, variance and standard deviation of a set of samples.
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* <em>Not thread safe!</em>
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*/
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public class RunningStats
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{
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/**
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* Adds a new sample.
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*/
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public void addSample (double sample)
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{
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// From http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#On-line_algorithm
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_numSamples++;
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double deltaToOld = sample - _mean;
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_mean += deltaToOld / _numSamples;
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double deltaToNew = sample - _mean;
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_varianceSum += deltaToOld * deltaToNew;
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if (sample < _min) {
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_min = sample;
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}
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if (sample > _max) {
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_max = sample;
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}
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}
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/**
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* Returns the minimum sample added or {@link Double#POSITIVE_INFINITY} if no samples have
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* been added.
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*/
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public double getMin ()
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{
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return _min;
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}
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/**
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* Returns the maximum sample added or {@link Double#NEGATIVE_INFINITY} if no samples have
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* been added.
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*/
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public double getMax ()
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{
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return _max;
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}
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public double getVariance ()
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{
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if (getNumSamples() == 0) {
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return 0;
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}
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return _varianceSum / getNumSamples();
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}
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public int getNumSamples ()
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{
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return _numSamples;
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}
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public double getMean ()
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{
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return _mean;
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}
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public double getStandardDeviation ()
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{
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return Math.sqrt(getVariance());
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}
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protected int _numSamples;
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protected double _mean;
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protected double _varianceSum;
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protected double _max = Double.NEGATIVE_INFINITY, _min = Double.POSITIVE_INFINITY;
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} |