# HG changeset patch
# User Sascha L. Teichmann <sascha.teichmann@intevation.de>
# Date 1338828296 0
# Node ID ab81ffd1343e1f4b391ad0af7529f5cb6eb1c320
# Parent  05a3fe8800b33840debccf6c7cc4fda9fcfb9021
FixA: Reactivated rewrite of the outlier checks.

flys-artifacts/trunk@4576 c6561f87-3c4e-4783-a992-168aeb5c3f6f

diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/ChangeLog
--- a/flys-artifacts/ChangeLog	Mon Jun 04 10:13:20 2012 +0000
+++ b/flys-artifacts/ChangeLog	Mon Jun 04 16:44:56 2012 +0000
@@ -1,3 +1,30 @@
+2012-06-04	Sascha L. Teichmann	<sascha.teichmann@intevation.de>
+
+	Implemented outlier checks in fixings analysis. Expected to be
+	still broken, but the code is in the right place now and has the
+	right structure.
+
+	* src/main/java/de/intevation/flys/artifacts/math/Outlier.java:
+	  Fixed endless loop.
+
+	* src/main/java/de/intevation/flys/artifacts/model/Parameters.java:
+	  Added further set methods for indexed access.
+
+	* src/main/java/de/intevation/flys/artifacts/model/fixings/Fitting.java:
+	  New. Out factored fitting code from FixCalculation. Checks for outliers, too.
+
+	* src/main/java/de/intevation/flys/artifacts/model/fixings/FixCalculation.java:
+	  Moved fitting code out to separate class. Streamlined code a bit.
+
+	* src/main/java/de/intevation/flys/artifacts/model/fixings/FixResult.java:
+	  Store the outliers from fitting in separate data structure, too.
+
+	* src/main/java/de/intevation/flys/artifacts/model/fixings/QW.java: New.
+	  Base class for delta W/t data. Used as storage for outliers.
+
+	* src/main/java/de/intevation/flys/artifacts/model/fixings/QWD.java:
+	  Is a sub class of QW now.
+
 2012-06-04	Sascha L. Teichmann	<sascha.teichmann@intevation.de>
 
 	* src/main/java/de/intevation/flys/artifacts/model/fixings/FixCalculation.java:
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/Outlier.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/Outlier.java	Mon Jun 04 10:13:20 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/Outlier.java	Mon Jun 04 16:44:56 2012 +0000
@@ -7,6 +7,7 @@
 
 import org.apache.commons.math.distribution.TDistributionImpl;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.ArrayList;
 
@@ -14,9 +15,13 @@
 
 public class Outlier
 {
+    public static final double DEFAULT_ALPHA = 0.05;
+
     private static Logger log = Logger.getLogger(Outlier.class);
 
-    public static class IndexedValue {
+    public static class IndexedValue
+    implements          Comparable<IndexedValue>
+    {
         protected int    index;
         protected double value;
 
@@ -43,12 +48,60 @@
         public void setValue(double value) {
             this.value = value;
         }
+
+        @Override
+        public int compareTo(IndexedValue other) {
+            int diff = index - other.index;
+            if (index < 0) return -1;
+            return index > 0 ? +1 : 0;
+        }
     } // class IndexedValue
 
+    public static class Outliers {
+
+        protected List<IndexedValue> retained;
+        protected List<IndexedValue> removed;
+
+        public Outliers() {
+        }
+
+        public Outliers(
+            List<IndexedValue> retained,
+            List<IndexedValue> removed
+        ) {
+            this.retained = retained;
+            this.removed  = removed;
+        }
+
+        public boolean hasOutliers() {
+            return !removed.isEmpty();
+        }
+
+        public List<IndexedValue> getRetained() {
+            return retained;
+        }
+
+        public void setRetained(List<IndexedValue> retained) {
+            this.retained = retained;
+        }
+
+        public List<IndexedValue> getRemoved() {
+            return removed;
+        }
+
+        public void setRemoved(List<IndexedValue> removed) {
+            this.removed = removed;
+        }
+    } // class Outliers
+
     public Outlier() {
     }
 
-    public static List<IndexedValue> findOutliers(
+    public static Outliers findOutliers(List<IndexedValue> inputValues) {
+        return findOutliers(inputValues, DEFAULT_ALPHA);
+    }
+
+    public static Outliers findOutliers(
         List<IndexedValue> inputValues,
         double             alpha
     ) {
@@ -69,7 +122,7 @@
 
             for (IndexedValue value: values) {
                 mean.increment(value.getValue());
-                std.increment(value.getValue());
+                std .increment(value.getValue());
             }
 
             double m = mean.getResult();
@@ -98,14 +151,18 @@
                     outliers.add(values.get(iv));
                     values.remove(iv);
                 }
+                else {
+                    break;
+                }
             }
             catch (MathException me) {
                 log.error(me);
             }
         }
 
+        Collections.sort(outliers);
 
-        return outliers;
+        return new Outliers(values, outliers);
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/Parameters.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/Parameters.java	Mon Jun 04 10:13:20 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/Parameters.java	Mon Jun 04 16:44:56 2012 +0000
@@ -40,7 +40,6 @@
     public int newRow() {
 
         int N = columns[0].size();
-        log.debug("new row: " + N);
 
         for (int i = 0; i < columns.length; ++i) {
             columns[i].add(Double.NaN);
@@ -71,6 +70,20 @@
         }
     }
 
+    public boolean set(int row, int [] indices, double [] values) {
+        boolean invalid = false;
+        for (int i = 0; i < indices.length; ++i) {
+            double v = values[i];
+            if (Double.isNaN(v)) {
+                invalid = true;
+            }
+            else {
+                columns[indices[i]].setQuick(row, v);
+            }
+        }
+        return invalid;
+    }
+
     public int size() {
         return columns[0].size();
     }
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/Fitting.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/Fitting.java	Mon Jun 04 16:44:56 2012 +0000
@@ -0,0 +1,170 @@
+package de.intevation.flys.artifacts.model.fixings;
+
+import de.intevation.flys.artifacts.math.fitting.Function;
+
+import de.intevation.flys.artifacts.math.Outlier;
+
+import de.intevation.flys.artifacts.math.Outlier.IndexedValue;
+import de.intevation.flys.artifacts.math.Outlier.Outliers;
+
+import org.apache.commons.math.MathException;
+
+import org.apache.commons.math.optimization.fitting.CurveFitter;
+
+import org.apache.commons.math.optimization.general.LevenbergMarquardtOptimizer;
+
+import gnu.trove.TDoubleArrayList;
+
+import org.apache.log4j.Logger;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Fitting
+{
+    private static Logger log = Logger.getLogger(Fitting.class);
+
+    /** Use instance of this factory to find meta infos for outliers. */
+    public interface QWFactory {
+
+        QW create(double q, double w);
+
+    } // interface QWFactory
+
+    protected Function      function;
+    protected QWFactory     qwFactory;
+    protected double        chiSqr;
+    protected double []     parameters;
+    protected ArrayList<QW> removed;
+
+
+    public Fitting() {
+        removed = new ArrayList<QW>();
+    }
+
+    public Fitting(Function function) {
+        this();
+        this.function = function;
+    }
+
+    public Fitting(Function function, QWFactory qwFactory) {
+        this(function);
+        this.qwFactory = qwFactory;
+    }
+
+    public Function getFunction() {
+        return function;
+    }
+
+    public void setFunction(Function function) {
+        this.function = function;
+    }
+
+    public double getChiSquare() {
+        return chiSqr;
+    }
+
+    public void reset() {
+        chiSqr     = 0.0;
+        parameters = null;
+        removed.clear();
+    }
+
+    public boolean hasOutliers() {
+        return !removed.isEmpty();
+    }
+
+    public List<QW> getOutliers() {
+        return removed;
+    }
+
+    public QW [] outliersToArray() {
+        return removed.toArray(new QW[removed.size()]);
+    }
+
+    public double [] getParameters() {
+        return parameters;
+    }
+
+    public boolean fit(double [] qs, double [] ws) {
+
+        TDoubleArrayList xs = new TDoubleArrayList(qs.length);
+        TDoubleArrayList ys = new TDoubleArrayList(ws.length);
+
+        for (int i = 0; i < qs.length; ++i) {
+            if (!Double.isNaN(qs[i]) && !Double.isNaN(ws[i])) {
+                xs.add(qs[i]);
+                ys.add(ws[i]);
+            }
+            else {
+                log.warn("remove invalid value " + qs[i] + " " + ws[i]);
+            }
+        }
+
+        if (xs.size() < 2) {
+            return false;
+        }
+
+        LevenbergMarquardtOptimizer lmo = new LevenbergMarquardtOptimizer();
+
+        double [] parameters;
+
+        List<IndexedValue> inputs = new ArrayList<IndexedValue>(xs.size());
+
+        for (;;) {
+            CurveFitter cf = new CurveFitter(lmo);
+
+            for (int i = 0, N = xs.size(); i < N; ++i) {
+                cf.addObservedPoint(xs.getQuick(i), ys.getQuick(i));
+            }
+
+            try {
+                parameters = cf.fit(function, function.getInitialGuess());
+            }
+            catch (MathException me) {
+                log.warn(me);
+                return false;
+            }
+
+            if (qwFactory == null) {
+                break;
+            }
+
+            inputs.clear();
+
+            // This is the paraterized function for a given km.
+            de.intevation.flys.artifacts.math.Function instance =
+                function.instantiate(parameters);
+
+            for (int i = 0, N = xs.size(); i < N; ++i) {
+                double y = instance.value(xs.getQuick(i));
+                if (Double.isNaN(y)) {
+                    continue;
+                }
+                inputs.add(new IndexedValue(i, ys.getQuick(i) - y));
+            }
+
+            Outliers outliers = Outlier.findOutliers(inputs);
+
+            if (!outliers.hasOutliers()) {
+                break;
+            }
+
+            List<IndexedValue> rem = outliers.getRemoved();
+
+            for (int i = rem.size()-1; i >= 0; --i) {
+                int idx = rem.get(i).getIndex();
+                removed.add(
+                    qwFactory.create(
+                        xs.getQuick(idx), ys.getQuick(idx)));
+                xs.remove(idx);
+                ys.remove(idx);
+            }
+        }
+
+        chiSqr = lmo.getChiSquare();
+
+        return true;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/FixCalculation.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/FixCalculation.java	Mon Jun 04 10:13:20 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/FixCalculation.java	Mon Jun 04 16:44:56 2012 +0000
@@ -25,19 +25,14 @@
 
 import de.intevation.flys.utils.DateAverager;
 import de.intevation.flys.utils.DoubleUtil;
-import de.intevation.flys.utils.Pair;
+import de.intevation.flys.utils.EpsilonComparator;
 
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-
-import org.apache.commons.math.MathException;
-
-import org.apache.commons.math.optimization.fitting.CurveFitter;
-
-import org.apache.commons.math.optimization.general.LevenbergMarquardtOptimizer;
+import java.util.TreeMap;
 
 import org.apache.log4j.Logger;
 
@@ -46,6 +41,8 @@
 {
     private static Logger log = Logger.getLogger(FixCalculation.class);
 
+    public static final double EPSILON = 1e-4;
+
     protected String       river;
     protected double       from;
     protected double       to;
@@ -71,6 +68,7 @@
         DateRange [] analysisPeriods = access.getAnalysisPeriods();
         Integer   qSectorStart       = access.getQSectorStart();
         Integer   qSectorEnd         = access.getQSectorEnd();
+        Boolean   preprocessing      = access.getPreprocessing();
 
         if (river == null) {
             // TODO: i18n
@@ -117,6 +115,11 @@
             addProblem("fix.missing.qend.sector");
         }
 
+        if (preprocessing == null) {
+            // TODO: i18n
+            addProblem("fix.missing.preprocessing");
+        }
+
         if (!hasProblems()) {
             this.river           = river;
             this.from            = from;
@@ -127,6 +130,7 @@
             this.analysisPeriods = analysisPeriods;
             this.qSectorStart    = qSectorStart;
             this.qSectorEnd      = qSectorEnd;
+            this.preprocessing   = preprocessing;
         }
     }
 
@@ -153,30 +157,9 @@
             return new CalculationResult(this);
         }
 
-        FixingsColumnFactory fcf = FixingsColumnFactory.getInstance();
-
-        List<FixingsColumn> dataColumns =
-            new ArrayList<FixingsColumn>(events.length);
-
-        for (int eventId: events) {
-            IdFilter idFilter = new IdFilter(eventId);
+        final List<Column> eventColumns = getEventColumns(overview);
 
-            List<Fixing.Column> columns = overview.filter(null, idFilter);
-            if (columns.isEmpty()) {
-                // TODO: i18n
-                addProblem("fix.missing.column", eventId);
-                continue;
-            }
-            FixingsColumn dataColumn = fcf.getColumnData(columns.get(0));
-            if (dataColumn == null) {
-                // TODO: i18n
-                addProblem("fix.cannot.load.data", eventId);
-                continue;
-            }
-            dataColumns.add(dataColumn);
-        }
-
-        if (dataColumns.size() < 2) {
+        if (eventColumns.size() < 2) {
             // TODO: i18n
             addProblem("fix.too.less.data.columns");
             return new CalculationResult(this);
@@ -184,8 +167,33 @@
 
         double [] kms = DoubleUtil.explode(from, to, step / 1000.0);
 
-        double [] ws = new double[dataColumns.size()];
-        double [] qs = new double[ws.length];
+        final double [] qs = new double[eventColumns.size()];
+        final double [] ws = new double[qs.length];
+
+        // Depending on preprocessing we need to find the outliers.
+        Fitting.QWFactory qwFactory = !preprocessing
+            ? null // No outliers
+            : new Fitting.QWFactory() {
+                @Override
+                public QW create(double q, double w) {
+                    // Check all the event columns for close match
+                    // and take the description and the date from meta.
+                    for (int i = 0; i < qs.length; ++i) {
+                        if (Math.abs(qs[i]-q) < EPSILON
+                        &&  Math.abs(ws[i]-w) < EPSILON) {
+                            Column column = eventColumns.get(i);
+                            return new QW(
+                                q, w,
+                                column.getDescription(),
+                                column.getDate());
+                        }
+                    }
+                    log.warn("cannot find column for (" + q + ", " + w + ")");
+                    return new QW(q, w);
+                }
+            };
+
+        Fitting fitting = new Fitting(func, qwFactory);
 
         String [] parameterNames = func.getParameterNames();
 
@@ -198,43 +206,44 @@
             log.debug("number of kms: " + kms.length);
         }
 
-        int kmIndex     = results.columnIndex("km");
-        int chiSqrIndex = results.columnIndex("chi_sqr");
+        TreeMap<Double, QW []> outliers =
+            new TreeMap<Double, QW []>(EpsilonComparator.INSTANCE);
+
+        int kmIndex             = results.columnIndex("km");
+        int chiSqrIndex         = results.columnIndex("chi_sqr");
+        int [] parameterIndices = results.columnIndices(parameterNames);
 
         int numFailed = 0;
 
         for (int i = 0; i < kms.length; ++i) {
             double km = kms[i];
 
+            // Fill Qs and Ws from event columns.
             for (int j = 0; j < ws.length; ++j) {
-                FixingsColumn column = dataColumns.get(j);
-                qs[j] = column.getQ(km);
-                boolean interpolated = column.getW(km, ws, j);
+                boolean interpolated =
+                    eventColumns.get(j).getQW(km, qs, ws, j);
                 // TODO: mark as interpolated.
             }
 
-            Pair<double [], Double> fitResult = fit(func, km, ws, qs);
+            fitting.reset();
 
-            // TODO: Do preprocessing here!
-            if (fitResult == null) { // Problems are reported already.
+            if (!fitting.fit(qs, ws)) {
                 ++numFailed;
+                // TODO: i18n
+                addProblem(km, "fix.fitting.failed");
                 continue;
             }
 
+            if (fitting.hasOutliers()) {
+                outliers.put(Double.valueOf(km), fitting.outliersToArray());
+            }
+
             int row = results.newRow();
 
             results.set(row, kmIndex, km);
-            results.set(row, chiSqrIndex, fitResult.getB());
-
-            double [] parameters = fitResult.getA();
-            for (int j = 0; j < parameters.length; ++j) {
-                if (Double.isNaN(parameters[j])) {
-                    invalid = true;
-                }
-                else {
-                    results.set(row, parameterNames[j], parameters[j]);
-                }
-            }
+            results.set(row, chiSqrIndex, fitting.getChiSquare());
+            invalid |= results.set(
+                row, parameterIndices, fitting.getParameters());
         }
 
         if (debug) {
@@ -254,11 +263,42 @@
             overview,
             results);
 
-        FixResult fr = new FixResult(results, deltaWTsKM);
+        FixResult fr = new FixResult(results, deltaWTsKM, outliers);
 
         return new CalculationResult(fr, this);
     }
 
+
+    protected List<Column> getEventColumns(FixingsOverview overview) {
+
+        FixingsColumnFactory fcf = FixingsColumnFactory.getInstance();
+
+        List<Column> columns = new ArrayList<Column>(events.length);
+
+        for (int eventId: events) {
+            IdFilter idFilter = new IdFilter(eventId);
+
+            List<Fixing.Column> metas = overview.filter(null, idFilter);
+
+            if (metas.isEmpty()) {
+                // TODO: i18n
+                addProblem("fix.missing.column", eventId);
+                continue;
+            }
+
+            FixingsColumn data = fcf.getColumnData(metas.get(0));
+            if (data == null) {
+                // TODO: i18n
+                addProblem("fix.cannot.load.data", eventId);
+                continue;
+            }
+
+            columns.add(new Column(metas.get(0), data));
+        }
+
+        return columns;
+    }
+
     public DeltaWTsKM calculateDeltaWTs(
         Function        function,
         FixingsOverview overview,
@@ -413,7 +453,7 @@
                         }
 
                         Column column = cc.getColumn(meta);
-                        if (column == null || !column.getWQ(km, wq)) {
+                        if (column == null || !column.getQW(km, wq)) {
                             continue;
                         }
 
@@ -427,7 +467,7 @@
                         Date date = column.getDate();
                         String description = column.getDescription();
 
-                        QWD qwd = new QWD(wq[1], wq[0], dw, date, description);
+                        QWD qwd = new QWD(wq[1], wq[0], description, date, dw);
 
                         qwds.add(qwd);
 
@@ -451,7 +491,7 @@
                             String avgDescription = "avg.deltawt." + qSector;
 
                             QWD avgQWD = new QWD(
-                                avgQ, avgW, avgDw, avgDate, avgDescription);
+                                avgQ, avgW, avgDescription, avgDate, avgDw);
 
                             // TODO: Store average value.
                         }
@@ -490,7 +530,17 @@
             return meta.getDescription();
         }
 
-        public boolean getWQ(double km, double [] wq) {
+        public boolean getQW(
+            double    km, 
+            double [] qs, 
+            double [] ws,
+            int       index
+        ) {
+            qs[index] = data.getQ(km);
+            return data.getW(km, ws, index);
+        }
+
+        public boolean getQW(double km, double [] wq) {
             data.getW(km, wq, 0);
             if (Double.isNaN(wq[0])) return false;
             wq[1] = data.getQ(km);
@@ -587,35 +637,5 @@
         System.arraycopy(parameters, 0, result, 2, parameters.length);
         return result;
     }
-
-    protected Pair<double [], Double> fit(
-        Function  function,
-        double    km,
-        double [] ws, 
-        double [] qs
-    ) {
-        LevenbergMarquardtOptimizer lmo = new LevenbergMarquardtOptimizer();
-        CurveFitter cf = new CurveFitter(lmo);
-
-        for (int i = 0; i < ws.length; ++i) {
-            if (!Double.isNaN(ws[i]) && !Double.isNaN(qs[i])) {
-                cf.addObservedPoint(qs[i], ws[i]);
-            }
-        }
-
-        try {
-            double [] parameters =
-                cf.fit(function, function.getInitialGuess());
-            double chiSqr = lmo.getChiSquare();
-
-            return new Pair<double [], Double>(parameters, chiSqr);
-        }
-        catch (MathException me) {
-            log.warn(me, me);
-            addProblem(km, "fix.fitting.failed");
-        }
-
-        return null;
-    }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/FixResult.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/FixResult.java	Mon Jun 04 10:13:20 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/FixResult.java	Mon Jun 04 16:44:56 2012 +0000
@@ -2,6 +2,8 @@
 
 import de.intevation.flys.artifacts.model.Parameters;
 
+import java.util.TreeMap;
+
 import java.io.Serializable;
 
 public class FixResult
@@ -9,13 +11,19 @@
 {
     protected Parameters parameters;
     protected DeltaWTsKM deltaWTsKM;
+    protected TreeMap<Double, QW []> outliers;
 
     public FixResult() {
     }
 
-    public FixResult(Parameters parameters, DeltaWTsKM deltaWTsKM) {
+    public FixResult(
+        Parameters             parameters,
+        DeltaWTsKM             deltaWTsKM,
+        TreeMap<Double, QW []> outliers
+    ) {
         this.parameters = parameters;
         this.deltaWTsKM = deltaWTsKM;
+        this.outliers   = outliers;
     }
 
     public Parameters getParameters() {
@@ -33,5 +41,13 @@
     public void setDeltaWTsKM(DeltaWTsKM deltaWTsKM) {
         this.deltaWTsKM = deltaWTsKM;
     }
+
+    public TreeMap<Double, QW []> getOutliers() {
+        return outliers;
+    }
+
+    public void setOutliers(TreeMap<Double, QW []> outliers) {
+        this.outliers = outliers;
+    }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/QW.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/QW.java	Mon Jun 04 16:44:56 2012 +0000
@@ -0,0 +1,61 @@
+package de.intevation.flys.artifacts.model.fixings;
+
+import java.util.Date;
+
+import java.io.Serializable;
+
+public class QW
+implements   Serializable
+{
+    protected double q;
+    protected double w;
+    protected String description;
+    protected Date   date;
+
+    public QW() {
+    }
+
+    public QW(double q, double w) {
+        this.q = q;
+        this.w = w;
+    }
+
+    public QW(double q, double w, String description, Date date) {
+        this(q, w);
+        this.description = description;
+        this.date        = date;
+    }
+
+    public double getQ() {
+        return q;
+    }
+
+    public void setQ(double q) {
+        this.q = q;
+    }
+
+    public double getW() {
+        return w;
+    }
+
+    public void setW(double w) {
+        this.w = w;
+    }
+
+    public Date getDate() {
+        return date;
+    }
+
+    public void setDate(Date date) {
+        this.date = date;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/QWD.java
--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/QWD.java	Mon Jun 04 10:13:20 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/fixings/QWD.java	Mon Jun 04 16:44:56 2012 +0000
@@ -2,16 +2,10 @@
 
 import java.util.Date;
 
-import java.io.Serializable;
-
 public class QWD
-implements   Serializable
+extends      QW
 {
-    protected double q;
-    protected double w;
     protected double deltaW;
-    protected Date   date;
-    protected String description;
 
     public QWD() {
     }
@@ -19,47 +13,20 @@
     public QWD(
         double q,
         double w,
-        double deltaW,
+        String description,
         Date   date,
-        String description
+        double deltaW
     ) {
-        this.q           = q;
-        this.w           = q;
-        this.deltaW      = deltaW;
-        this.date        = date;
-        this.description = description;
-    }
-
-    public double getQ() {
-        return q;
-    }
-
-    public void setQ(double q) {
-        this.q = q;
+        super(q, w, description, date);
+        this.deltaW = deltaW;
     }
 
-    public double getW() {
-        return w;
-    }
-
-    public void setW(double w) {
-        this.w = w;
+    public double getDeltaW() {
+        return deltaW;
     }
 
-    public Date getDate() {
-        return date;
-    }
-
-    public void setDate(Date date) {
-        this.date = date;
-    }
-
-    public String getDescription() {
-        return description;
-    }
-
-    public void setDescription(String description) {
-        this.description = description;
+    public void setDeltaW(double deltaW) {
+        this.deltaW = deltaW;
     }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
diff -r 05a3fe8800b3 -r ab81ffd1343e flys-artifacts/src/main/java/de/intevation/flys/utils/EpsilonComparator.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/utils/EpsilonComparator.java	Mon Jun 04 16:44:56 2012 +0000
@@ -0,0 +1,36 @@
+package de.intevation.flys.utils;
+
+import java.io.Serializable;
+
+import java.util.Comparator;
+
+public class EpsilonComparator
+implements   Serializable, Comparator<Double>
+{
+    public static final double EPSILON = 1e-5;
+
+    public static final EpsilonComparator INSTANCE =
+        new EpsilonComparator(EPSILON);
+
+    protected double epsilon;
+
+    public EpsilonComparator() {
+        this(EPSILON);
+    }
+
+    public EpsilonComparator(double epsilon) {
+        this.epsilon = Math.abs(epsilon);
+    }
+
+    private static final double value(Double x) {
+        return x != null ? x.doubleValue() : 0.0;
+    }
+
+    @Override
+    public int compare(Double a, Double b) {
+        double diff = value(a) - value(b);
+        if (diff < epsilon) return -1;
+        return diff > epsilon ? +1 : 0;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :