1 files changed, 163 insertions, 0 deletions
diff --git a/elki/src/main/java/de/lmu/ifi/dbs/elki/distance/distancefunction/geo/LatLngDistanceFunction.java b/elki/src/main/java/de/lmu/ifi/dbs/elki/distance/distancefunction/geo/LatLngDistanceFunction.java
new file mode 100644
index 00000000..2ccb13ec
--- /dev/null
+++ b/elki/src/main/java/de/lmu/ifi/dbs/elki/distance/distancefunction/geo/LatLngDistanceFunction.java
@@ -0,0 +1,163 @@
+package de.lmu.ifi.dbs.elki.distance.distancefunction.geo;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2015
+ Ludwig-Maximilians-Universität München
+ Lehr- und Forschungseinheit für Datenbanksysteme
+ ELKI Development Team
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Affero General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU Affero General Public License for more details.
+
+ You should have received a copy of the GNU Affero General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import de.lmu.ifi.dbs.elki.data.NumberVector;
+import de.lmu.ifi.dbs.elki.data.spatial.SpatialComparable;
+import de.lmu.ifi.dbs.elki.data.type.SimpleTypeInformation;
+import de.lmu.ifi.dbs.elki.data.type.TypeUtil;
+import de.lmu.ifi.dbs.elki.distance.distancefunction.AbstractSpatialDistanceFunction;
+import de.lmu.ifi.dbs.elki.math.geodesy.EarthModel;
+import de.lmu.ifi.dbs.elki.math.geodesy.SphericalVincentyEarthModel;
+import de.lmu.ifi.dbs.elki.utilities.documentation.Reference;
+import de.lmu.ifi.dbs.elki.utilities.exceptions.NotImplementedException;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizer;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameterization.Parameterization;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.ObjectParameter;
+
+/**
+ * Distance function for 2D vectors in Latitude, Longitude form.
+ * 
+ * The input data must be in degrees (not radians), and the output distance will
+ * be in meters (see {@link EarthModel#distanceDeg}).
+ * 
+ * This implementation allows index accelerated queries using R*-trees (by
+ * providing a point-to-rectangle minimum distance), as published in:
+ * <p>
+ * Erich Schubert, Arthur Zimek and Hans-Peter Kriegel<br />
+ * Geodetic Distance Queries on R-Trees for Indexing Geographic Data<br />
+ * Advances in Spatial and Temporal Databases - 13th International Symposium,
+ * SSTD 2013, Munich, Germany
+ * </p>
+ * 
+ * @author Erich Schubert
+ * 
+ * @apiviz.composedOf EarthModel
+ */
+public class LatLngDistanceFunction extends AbstractSpatialDistanceFunction {
+  /**
+   * Earth model to use.
+   */
+  private EarthModel model;
+
+  /**
+   * Constructor.
+   */
+  public LatLngDistanceFunction(EarthModel model) {
+    super();
+    this.model = model;
+  }
+
+  @Override
+  public double distance(NumberVector o1, NumberVector o2) {
+    return model.distanceDeg(o1.doubleValue(0), o1.doubleValue(1), o2.doubleValue(0), o2.doubleValue(1));
+  }
+
+  @Override
+  @Reference(authors = "Erich Schubert, Arthur Zimek and Hans-Peter Kriegel", title = "Geodetic Distance Queries on R-Trees for Indexing Geographic Data", booktitle = "Advances in Spatial and Temporal Databases - 13th International Symposium, SSTD 2013, Munich, Germany")
+  public double minDist(SpatialComparable mbr1, SpatialComparable mbr2) {
+    if(mbr1 instanceof NumberVector) {
+      if(mbr2 instanceof NumberVector) {
+        return distance((NumberVector) mbr1, (NumberVector) mbr2);
+      }
+      else {
+        NumberVector o1 = (NumberVector) mbr1;
+        return model.minDistDeg(o1.doubleValue(0), o1.doubleValue(1), mbr2.getMin(0), mbr2.getMin(1), mbr2.getMax(0), mbr2.getMax(1));
+      }
+    }
+    else {
+      if(mbr2 instanceof NumberVector) {
+        NumberVector o2 = (NumberVector) mbr2;
+        return model.minDistDeg(o2.doubleValue(0), o2.doubleValue(1), mbr1.getMin(0), mbr1.getMin(1), mbr1.getMax(0), mbr1.getMax(1));
+      }
+      else {
+        throw new NotImplementedException("This distance function cannot - yet - be used with this algorithm, as the lower bound rectangle to rectangle distances have not yet been formalized for geodetic data.");
+      }
+    }
+  }
+
+  @Override
+  public SimpleTypeInformation<? super NumberVector> getInputTypeRestriction() {
+    return TypeUtil.NUMBER_VECTOR_FIELD_2D;
+  }
+
+  @Override
+  public int hashCode() {
+    final int prime = 31;
+    int result = 1;
+    result = prime * result + ((model == null) ? 0 : model.hashCode());
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if(this == obj) {
+      return true;
+    }
+    if(obj == null) {
+      return false;
+    }
+    if(getClass() != obj.getClass()) {
+      return false;
+    }
+    LatLngDistanceFunction other = (LatLngDistanceFunction) obj;
+    if(model == null) {
+      if(other.model != null) {
+        return false;
+      }
+    }
+    else if(!model.equals(other.model)) {
+      return false;
+    }
+    return true;
+  }
+
+  /**
+   * Parameterization class.
+   * 
+   * @author Erich Schubert
+   * 
+   * @apiviz.exclude
+   */
+  public static class Parameterizer extends AbstractParameterizer {
+    /**
+     * Earth model used.
+     */
+    EarthModel model;
+
+    @Override
+    protected void makeOptions(Parameterization config) {
+      super.makeOptions(config);
+      ObjectParameter<EarthModel> modelP = new ObjectParameter<>(EarthModel.MODEL_ID, EarthModel.class, SphericalVincentyEarthModel.class);
+      if(config.grab(modelP)) {
+        model = modelP.instantiateClass(config);
+      }
+    }
+
+    @Override
+    protected LatLngDistanceFunction makeInstance() {
+      return new LatLngDistanceFunction(model);
+    }
+  }
+}