Mercurial > dive4elements > river
diff flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/StdDevOutlier.java @ 4794:a7d080347ac3
MINFO: Allow two methods for outlier test in SQ relation.
* Methods can be switched as option in conf.xml.
* Methods:
- Find outliers via multiples of the standard deviation.
- Grubbs (used in Fix-Analysis)
author | Raimund Renkert <rrenkert@intevation.de> |
---|---|
date | Fri, 11 Jan 2013 13:57:38 +0100 |
parents | |
children | 8ee270a3ef25 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/StdDevOutlier.java Fri Jan 11 13:57:38 2013 +0100 @@ -0,0 +1,78 @@ +package de.intevation.flys.artifacts.math; + +import java.util.List; + +import org.apache.commons.math.MathException; + +import org.apache.commons.math.distribution.TDistributionImpl; + +import org.apache.commons.math.stat.descriptive.moment.Mean; +import org.apache.commons.math.stat.descriptive.moment.StandardDeviation; + +import org.apache.log4j.Logger; + +import de.intevation.flys.artifacts.model.sq.SQ; + +public class StdDevOutlier +{ + public static final double EPSILON = 1e-5; + + 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[] stdDevResult) { + boolean debug = log.isDebugEnabled(); + + if (debug) { + log.debug("factor for std dev: " + factor); + } + + int N = values.size(); + + if (debug) { + log.debug("Values to check: " + N); + } + + if (values.size() < 3) { + return null; + } + + StandardDeviation stdDev = new StandardDeviation(); + + double maxValue = -Double.MAX_VALUE; + int maxIndex = -1; + int ndx = 0; + for (int i = values.size()-1; i >= 0; --i) { + double value = Math.abs(values.get(i)); + stdDev.increment(value); + if (value > maxValue) { + maxValue = value; + maxIndex = ndx; + } + ++ndx; + } + + double sd = stdDev.getResult(); + + double accepted = factor * sd; + + if (debug) { + log.debug("std dev: " + stdDev); + log.debug("accepted: " + accepted); + log.debug("max value: " + maxValue); + } + if (stdDevResult != null) { + stdDevResult[0] = sd; + } + return maxValue > accepted ? maxIndex : null; + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :