Mercurial > dive4elements > river
view artifacts/src/main/java/org/dive4elements/river/artifacts/math/StdDevOutlier.java @ 8755:30b1ddadf275
(issue1801) Unify reference gauge finding code
The basic way as described in the method comment of the
determineRefGauge method is now used in the WINFOArtifact,
MainValuesService and RiverUtils.getGauge method.
RiverUtils.getGauge previously just returned the first
gauge found. While this is now a behavior change I believe
that it is always more correct then the undeterministic
behavior of the previous implmenentation.
author | Andre Heinecke <andre.heinecke@intevation.de> |
---|---|
date | Wed, 24 Jun 2015 14:07:26 +0200 |
parents | b265cd6cfda5 |
children | 5e38e2924c07 |
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/* Copyright (C) 2011, 2012, 2013 by Bundesanstalt für Gewässerkunde * Software engineering by Intevation GmbH * * This file is Free Software under the GNU AGPL (>=v3) * and comes with ABSOLUTELY NO WARRANTY! Check out the * documentation coming with Dive4Elements River for details. */ package org.dive4elements.river.artifacts.math; import java.util.List; import org.apache.log4j.Logger; /* XXX: * Warning: This class is called StdDevOutlier because it caculates the * Standard Deviation method for outlier removal as the BFG calls it. * But the actual calculation used to remove the outliers calculates * the Standard Error and not the Standard Deviation! */ public class StdDevOutlier { public static final double DEFAULT_FACTOR = 3; private static Logger log = Logger.getLogger(StdDevOutlier.class); protected StdDevOutlier() { } public static Integer findOutlier(List<Double> values) { return findOutlier(values, DEFAULT_FACTOR, null); } public static Integer findOutlier( List<Double> values, double factor, double [] stdErrResult ) { boolean debug = log.isDebugEnabled(); if (debug) { log.debug("factor for std dev test (that calculates std err): " + factor); } int N = values.size(); if (debug) { log.debug("Values to check: " + N); } if (N < 3) { return null; } double maxValue = -Double.MAX_VALUE; int maxIndex = -1; double squareSumResiduals = 0; for (Double db: values) { squareSumResiduals += Math.pow(db, 2); } double stdErr = Math.sqrt(squareSumResiduals / (N - 2)); double accepted = factor * stdErr; for (int i = N-1; i >= 0; --i) { double value = Math.abs(values.get(i)); if (value > maxValue) { maxValue = value; maxIndex = i; } } if (debug) { log.debug("std err: " + stdErr); log.debug("accepted: " + accepted); log.debug("max value: " + maxValue); } if (stdErrResult != null) { stdErrResult[0] = stdErr; } return maxValue > accepted ? maxIndex : null; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :