--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/common/GaugeDischargeValuesFinder.java	Mon Jun 25 19:21:11 2018 +0200
@@ -0,0 +1,118 @@
+/** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
+ * Software engineering by
+ *  Björnsen Beratende Ingenieure GmbH
+ *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
+ *
+ * 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.sinfo.common;
+
+import org.apache.commons.lang.math.DoubleRange;
+import org.apache.commons.math.FunctionEvaluationException;
+import org.apache.commons.math.analysis.UnivariateRealFunction;
+import org.apache.commons.math.analysis.interpolation.LinearInterpolator;
+import org.dive4elements.river.artifacts.model.Calculation;
+import org.dive4elements.river.model.DischargeTable;
+import org.dive4elements.river.model.DischargeTableValue;
+import org.dive4elements.river.model.Gauge;
+
+import gnu.trove.TDoubleArrayList;
+
+/**
+ * Loading and search/interpolation of a gauge's discharge table (.at)
+ *
+ * @author Matthias Schäfer
+ *
+ */
+public final class GaugeDischargeValuesFinder {
+
+    /***** FIELDS *****/
+
+    // private static Logger log = Logger.getLogger(GaugeDischargeValuesFinder.class);
+
+    private final Gauge gauge;
+
+    private Calculation problems;
+
+    private final UnivariateRealFunction wInterpolator;
+
+    private final DoubleRange wRange;
+
+
+    /***** CONSTRUCTORS *****/
+
+    private GaugeDischargeValuesFinder(final Gauge gauge, final Calculation problems, final DischargeTable dischargeTable) {
+        this.gauge = gauge;
+        this.problems = problems;
+        final TDoubleArrayList ws = new TDoubleArrayList();
+        final TDoubleArrayList qs = new TDoubleArrayList();
+        for (final DischargeTableValue v : DischargeTable.getValuesSortedByW(dischargeTable)) {
+            ws.add(v.getW().doubleValue());
+            qs.add(v.getQ().doubleValue());
+        }
+        if (ws.size() >= 2) {
+            this.wInterpolator = new LinearInterpolator().interpolate(ws.toNativeArray(), qs.toNativeArray());
+            this.wRange = new DoubleRange(ws.get(0), ws.get(ws.size() - 1));
+        }
+        else {
+            this.wInterpolator = null;
+            this.wRange = null;
+        }
+        if ((this.wInterpolator == null) && (this.problems != null)) {
+            this.problems.addProblem("gauge_discharge_table.missing", gauge.getName());
+            // Report only once
+            this.problems = null;
+        }
+    }
+
+
+    /***** METHODS *****/
+
+    /**
+     * Loads the the main discharge table of a gauge (GAUGE.at)
+     *
+     * @return The discharge table values finder of the gauge, or null
+     */
+    public static GaugeDischargeValuesFinder loadValues(final Gauge gauge, final Calculation problems) {
+        final DischargeTable table = DischargeTable.getGaugeMainDischargeTable(gauge);
+        if ((table == null) || (table.getDischargeTableValues().size() == 0)) {
+            problems.addProblem("gauge_discharge_table.missing", gauge.getName());
+            return null;
+        }
+        else
+            return new GaugeDischargeValuesFinder(gauge, problems, table);
+    }
+
+    /**
+     * If this provider may return valid data at all.
+     */
+    public boolean isValid() {
+        return (this.wInterpolator != null);
+    }
+
+    /**
+     * Discharge for a W
+     *
+     * @param w
+     *            W in cm above gauge datum
+     * @return Q, or NegInf for w less than all, or PosInf for w greater then all, or NaN in case of exception
+     */
+    public double getDischarge(final double w) {
+        try {
+            if (this.wInterpolator == null)
+                return Double.NaN;
+            else if (w < this.wRange.getMinimumDouble())
+                return Double.NEGATIVE_INFINITY;
+            else if (w > this.wRange.getMaximumDouble())
+                return Double.POSITIVE_INFINITY;
+            else
+                return this.wInterpolator.value(w);
+        }
+        catch (@SuppressWarnings("unused") final FunctionEvaluationException e) {
+            // ignore exception because this can/will happen regularly
+            return Double.NaN;
+        }
+    }
+}
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