1 files changed, 62 insertions, 57 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/utilities/referencepoints/GridBasedReferencePoints.java b/src/de/lmu/ifi/dbs/elki/utilities/referencepoints/GridBasedReferencePoints.java
index 007efe6f..5ebee64b 100644
--- a/src/de/lmu/ifi/dbs/elki/utilities/referencepoints/GridBasedReferencePoints.java
+++ b/src/de/lmu/ifi/dbs/elki/utilities/referencepoints/GridBasedReferencePoints.java
@@ -4,7 +4,7 @@ package de.lmu.ifi.dbs.elki.utilities.referencepoints;
  This file is part of ELKI:
  Environment for Developing KDD-Applications Supported by Index-Structures
 
- Copyright (C) 2013
+ Copyright (C) 2014
  Ludwig-Maximilians-Universität München
  Lehr- und Forschungseinheit für Datenbanksysteme
  ELKI Development Team
@@ -29,50 +29,35 @@ import java.util.Collection;
 import de.lmu.ifi.dbs.elki.data.NumberVector;
 import de.lmu.ifi.dbs.elki.database.relation.Relation;
 import de.lmu.ifi.dbs.elki.database.relation.RelationUtil;
+import de.lmu.ifi.dbs.elki.logging.Logging;
 import de.lmu.ifi.dbs.elki.math.MathUtil;
-import de.lmu.ifi.dbs.elki.utilities.DatabaseUtil;
+import de.lmu.ifi.dbs.elki.math.linearalgebra.Vector;
+import de.lmu.ifi.dbs.elki.utilities.exceptions.AbortException;
 import de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizer;
 import de.lmu.ifi.dbs.elki.utilities.optionhandling.OptionID;
 import de.lmu.ifi.dbs.elki.utilities.optionhandling.constraints.CommonConstraints;
 import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameterization.Parameterization;
 import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.DoubleParameter;
 import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.IntParameter;
-import de.lmu.ifi.dbs.elki.utilities.pairs.Pair;
 
 /**
  * Grid-based strategy to pick reference points.
  * 
  * @author Erich Schubert
- * 
- * @param <V> Object type
  */
-public class GridBasedReferencePoints<V extends NumberVector<?>> implements ReferencePointsHeuristic<V> {
-  // TODO: add "grid sampling" option.
-
-  /**
-   * Parameter to specify the grid resolution.
-   * <p>
-   * Key: {@code -grid.size}
-   * </p>
-   */
-  public static final OptionID GRID_ID = new OptionID("grid.size", "The number of partitions in each dimension. Points will be placed on the edges of the grid, except for a grid size of 0, where only the mean is generated as reference point.");
-
+public class GridBasedReferencePoints implements ReferencePointsHeuristic {
   /**
-   * Parameter to specify the extra scaling of the space, to allow
-   * out-of-data-space reference points.
-   * <p>
-   * Key: {@code -grid.oversize}
-   * </p>
+   * Class logger.
    */
-  public static final OptionID GRID_SCALE_ID = new OptionID("grid.scale", "Scale the grid by the given factor. This can be used to obtain reference points outside the used data space.");
+  private static final Logging LOG = Logging.getLogger(GridBasedReferencePoints.class);
 
   /**
-   * Holds the value of {@link #GRID_ID}.
+   * Holds the grid resolution.
    */
   protected int gridres;
 
   /**
-   * Holds the value of {@link #GRID_SCALE_ID}.
+   * Holds the grid scale.
    */
   protected double gridscale;
 
@@ -89,46 +74,47 @@ public class GridBasedReferencePoints<V extends NumberVector<?>> implements Refe
   }
 
   @Override
-  public <T extends V> Collection<V> getReferencePoints(Relation<T> db) {
-    Relation<V> database = DatabaseUtil.relationUglyVectorCast(db);
-    Pair<V, V> minmax = DatabaseUtil.computeMinMax(database);
-    NumberVector.Factory<V, ?> factory = RelationUtil.getNumberVectorFactory(database);
-
-    int dim = RelationUtil.dimensionality(db);
+  public Collection<? extends NumberVector> getReferencePoints(Relation<? extends NumberVector> db) {
+    double[][] minmax = RelationUtil.computeMinMax(db);
+    final int dim = minmax[0].length;
 
     // Compute mean from minmax.
     double[] mean = new double[dim];
     for(int d = 0; d < dim; d++) {
-      mean[d] = (minmax.first.doubleValue(d) + minmax.second.doubleValue(d)) * .5;
+      mean[d] = (minmax[0][d] + minmax[1][d]) * .5;
     }
 
-    int gridpoints = Math.max(1, MathUtil.ipowi(gridres + 1, dim));
-    ArrayList<V> result = new ArrayList<>(gridpoints);
+    if(gridres <= 0) {
+      LOG.warning("Grid of resolution " + gridres + " will have a single point only.");
+      ArrayList<Vector> result = new ArrayList<>(1);
+      result.add(new Vector(mean));
+      return result;
+    }
+    final int grids = gridres + 1;
+    final int gridpoints = MathUtil.ipowi(grids, dim);
+    if(gridpoints < 0) {
+      throw new AbortException("Grids with more than 2^31 are not supported, or meaningful.");
+    }
+    if(gridpoints < 0 || gridpoints > db.size()) {
+      LOG.warning("Grid has " + gridpoints + " points, but you only have " + db.size() + " observations.");
+    }
+    ArrayList<Vector> result = new ArrayList<>(gridpoints);
     double[] delta = new double[dim];
-    if(gridres > 0) {
-      double halfgrid = gridres / 2.0;
-      for(int d = 0; d < dim; d++) {
-        delta[d] = (minmax.second.doubleValue(d) - minmax.first.doubleValue(d)) / gridres;
-      }
+    for(int d = 0; d < dim; d++) {
+      delta[d] = (minmax[1][d] - minmax[0][d]) / gridres;
+    }
 
-      double[] vec = new double[dim];
-      for(int i = 0; i < gridpoints; i++) {
-        int acc = i;
-        for(int d = 0; d < dim; d++) {
-          int coord = acc % (gridres + 1);
-          acc = acc / (gridres + 1);
-          vec[d] = mean[d] + (coord - halfgrid) * delta[d] * gridscale;
-        }
-        V newp = factory.newNumberVector(vec);
-        // logger.debug("New reference point: " + FormatUtil.format(vec));
-        result.add(newp);
+    double halfgrid = gridres * .5;
+    for(int i = 0; i < gridpoints; i++) {
+      double[] vec = new double[dim]; // Will be returned!
+      int acc = i;
+      for(int d = 0; d < dim; d++) {
+        int coord = acc % grids;
+        acc /= grids;
+        vec[d] = mean[d] + (coord - halfgrid) * delta[d] * gridscale;
       }
+      result.add(new Vector(vec));
     }
-    else {
-      result.add(factory.newNumberVector(mean));
-      // logger.debug("New reference point: " + FormatUtil.format(mean));
-    }
-
     return result;
   }
 
@@ -139,7 +125,26 @@ public class GridBasedReferencePoints<V extends NumberVector<?>> implements Refe
    * 
    * @apiviz.exclude
    */
-  public static class Parameterizer<V extends NumberVector<?>> extends AbstractParameterizer {
+  public static class Parameterizer extends AbstractParameterizer {
+    // TODO: add "grid sampling" option.
+
+    /**
+     * Parameter to specify the grid resolution.
+     * <p>
+     * Key: {@code -grid.size}
+     * </p>
+     */
+    public static final OptionID GRID_ID = new OptionID("grid.size", "The number of partitions in each dimension. Points will be placed on the edges of the grid, except for a grid size of 0, where only the mean is generated as reference point.");
+
+    /**
+     * Parameter to specify the extra scaling of the space, to allow
+     * out-of-data-space reference points.
+     * <p>
+     * Key: {@code -grid.oversize}
+     * </p>
+     */
+    public static final OptionID GRID_SCALE_ID = new OptionID("grid.scale", "Scale the grid by the given factor. This can be used to obtain reference points outside the used data space.");
+
     /**
      * Holds the value of {@link #GRID_ID}.
      */
@@ -167,8 +172,8 @@ public class GridBasedReferencePoints<V extends NumberVector<?>> implements Refe
     }
 
     @Override
-    protected GridBasedReferencePoints<V> makeInstance() {
-      return new GridBasedReferencePoints<>(gridres, gridscale);
+    protected GridBasedReferencePoints makeInstance() {
+      return new GridBasedReferencePoints(gridres, gridscale);
     }
   }
 }