Mercurial > dive4elements > river
comparison flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/Outlier.java @ 2645:4f7d1ea38404
Added simple Grubb's outlier test.
flys-artifacts/trunk@4300 c6561f87-3c4e-4783-a992-168aeb5c3f6f
| author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
|---|---|
| date | Wed, 25 Apr 2012 15:57:23 +0000 |
| parents | |
| children | c11da3540b70 |
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| 2644:0a84313efe60 | 2645:4f7d1ea38404 |
|---|---|
| 1 package de.intevation.flys.artifacts.math; | |
| 2 | |
| 3 import org.apache.commons.math.stat.descriptive.moment.Mean; | |
| 4 import org.apache.commons.math.stat.descriptive.moment.StandardDeviation; | |
| 5 | |
| 6 import org.apache.commons.math.distribution.TDistributionImpl; | |
| 7 | |
| 8 import java.util.List; | |
| 9 import java.util.ArrayList; | |
| 10 | |
| 11 public class Outlier | |
| 12 { | |
| 13 public static class IndexedValue { | |
| 14 protected int index; | |
| 15 protected double value; | |
| 16 | |
| 17 public IndexedValue() { | |
| 18 } | |
| 19 | |
| 20 public IndexedValue(int index, double value) { | |
| 21 this.index = index; | |
| 22 this.value = value; | |
| 23 } | |
| 24 | |
| 25 public int getIndex() { | |
| 26 return index; | |
| 27 } | |
| 28 | |
| 29 public void setIndex(int index) { | |
| 30 this.index = index; | |
| 31 } | |
| 32 | |
| 33 public double getValue() { | |
| 34 return value; | |
| 35 } | |
| 36 | |
| 37 public void setValue(double value) { | |
| 38 this.value = value; | |
| 39 } | |
| 40 } // class IndexedValue | |
| 41 | |
| 42 public Outlier() { | |
| 43 } | |
| 44 | |
| 45 public static List<IndexedValue> findOutliers( | |
| 46 List<IndexedValue> inputValues, | |
| 47 double alpha | |
| 48 ) { | |
| 49 ArrayList<IndexedValue> outliers = new ArrayList<IndexedValue>(); | |
| 50 | |
| 51 ArrayList<IndexedValue> values = | |
| 52 new ArrayList<IndexedValue>(inputValues); | |
| 53 | |
| 54 for (;;) { | |
| 55 int N = values.size(); | |
| 56 | |
| 57 if (N < 4) { | |
| 58 break; | |
| 59 } | |
| 60 | |
| 61 Mean mean = new Mean(); | |
| 62 StandardDeviation std = new StandardDeviation(); | |
| 63 | |
| 64 for (IndexedValue value: values) { | |
| 65 mean.increment(value.getValue()); | |
| 66 std.increment(value.getValue()); | |
| 67 } | |
| 68 | |
| 69 double m = mean.getResult(); | |
| 70 double s = std.getResult(); | |
| 71 | |
| 72 double maxZ = -Double.MAX_VALUE; | |
| 73 int iv = -1; | |
| 74 for (int i >= 0; i = N-1; --i) { | |
| 75 IndexedValue v = values.get(i); | |
| 76 double z = Math.abs(m - v.getValue())/s; | |
| 77 if (z > maxZ) { | |
| 78 maxZ = z; | |
| 79 iv = i; | |
| 80 } | |
| 81 } | |
| 82 | |
| 83 double t = Math.sqrt((N*(N-2)*z*z)/((N-1)*(N-1) - N*z*z)) | |
| 84 | |
| 85 TDistributionImpl tdist = new TDistributionImpl(N-2); | |
| 86 | |
| 87 double p = tdist.cumulativeProbability(t) | |
| 88 } | |
| 89 | |
| 90 | |
| 91 return outliers; | |
| 92 } | |
| 93 } | |
| 94 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |