Mercurial > dive4elements > river
comparison artifacts/src/main/java/org/dive4elements/river/artifacts/math/StdDevOutlier.java @ 5838:5aa05a7a34b7
Rename modules to more fitting names.
| author | Sascha L. Teichmann <teichmann@intevation.de> |
|---|---|
| date | Thu, 25 Apr 2013 15:23:37 +0200 |
| parents | flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/StdDevOutlier.java@bd047b71ab37 |
| children | 4897a58c8746 |
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| 5837:d9901a08d0a6 | 5838:5aa05a7a34b7 |
|---|---|
| 1 package org.dive4elements.river.artifacts.math; | |
| 2 | |
| 3 import java.util.List; | |
| 4 | |
| 5 import org.apache.commons.math.stat.descriptive.moment.StandardDeviation; | |
| 6 | |
| 7 import org.apache.log4j.Logger; | |
| 8 | |
| 9 public class StdDevOutlier | |
| 10 { | |
| 11 public static final double DEFAULT_FACTOR = 3; | |
| 12 | |
| 13 private static Logger log = Logger.getLogger(StdDevOutlier.class); | |
| 14 | |
| 15 protected StdDevOutlier() { | |
| 16 } | |
| 17 | |
| 18 public static Integer findOutlier(List<Double> values) { | |
| 19 return findOutlier(values, DEFAULT_FACTOR, null); | |
| 20 } | |
| 21 | |
| 22 public static Integer findOutlier( | |
| 23 List<Double> values, | |
| 24 double factor, | |
| 25 double [] stdDevResult | |
| 26 ) { | |
| 27 boolean debug = log.isDebugEnabled(); | |
| 28 | |
| 29 if (debug) { | |
| 30 log.debug("factor for std dev: " + factor); | |
| 31 } | |
| 32 | |
| 33 int N = values.size(); | |
| 34 | |
| 35 if (debug) { | |
| 36 log.debug("Values to check: " + N); | |
| 37 } | |
| 38 | |
| 39 if (N < 3) { | |
| 40 return null; | |
| 41 } | |
| 42 | |
| 43 StandardDeviation stdDev = new StandardDeviation(); | |
| 44 | |
| 45 double maxValue = -Double.MAX_VALUE; | |
| 46 int maxIndex = -1; | |
| 47 for (int i = N-1; i >= 0; --i) { | |
| 48 double value = Math.abs(values.get(i)); | |
| 49 stdDev.increment(value); | |
| 50 if (value > maxValue) { | |
| 51 maxValue = value; | |
| 52 maxIndex = i; | |
| 53 } | |
| 54 } | |
| 55 | |
| 56 double sd = stdDev.getResult(); | |
| 57 | |
| 58 double accepted = factor * sd; | |
| 59 | |
| 60 if (debug) { | |
| 61 log.debug("std dev: " + stdDev); | |
| 62 log.debug("accepted: " + accepted); | |
| 63 log.debug("max value: " + maxValue); | |
| 64 } | |
| 65 | |
| 66 if (stdDevResult != null) { | |
| 67 stdDevResult[0] = sd; | |
| 68 } | |
| 69 | |
| 70 return maxValue > accepted ? maxIndex : null; | |
| 71 } | |
| 72 } | |
| 73 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |