1 files changed, 97 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/algorithm/outlier/lof/parallel/SimplifiedLRDProcessor.java b/src/de/lmu/ifi/dbs/elki/algorithm/outlier/lof/parallel/SimplifiedLRDProcessor.java
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+++ b/src/de/lmu/ifi/dbs/elki/algorithm/outlier/lof/parallel/SimplifiedLRDProcessor.java
@@ -0,0 +1,97 @@
+package de.lmu.ifi.dbs.elki.algorithm.outlier.lof.parallel;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2014
+ 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.database.datastore.DataStore;
+import de.lmu.ifi.dbs.elki.database.ids.DBIDRef;
+import de.lmu.ifi.dbs.elki.database.ids.DBIDUtil;
+import de.lmu.ifi.dbs.elki.database.ids.DoubleDBIDListIter;
+import de.lmu.ifi.dbs.elki.database.ids.KNNList;
+import de.lmu.ifi.dbs.elki.parallel.Executor;
+import de.lmu.ifi.dbs.elki.parallel.processor.AbstractDoubleProcessor;
+import de.lmu.ifi.dbs.elki.parallel.variables.SharedDouble;
+
+/**
+ * Processor for the "local reachability density" of LOF.
+ * 
+ * Note: we compute 1/lrd, the local reachability distance.
+ * 
+ * @author Erich Schubert
+ *
+ * @apiviz.has Instance
+ */
+public class SimplifiedLRDProcessor extends AbstractDoubleProcessor {
+  /**
+   * KNN store
+   */
+  private DataStore<? extends KNNList> knns;
+
+  /**
+   * Constructor.
+   * 
+   * @param knns k nearest neighbors
+   */
+  public SimplifiedLRDProcessor(DataStore<? extends KNNList> knns) {
+    super();
+    this.knns = knns;
+  }
+
+  @Override
+  public Instance instantiate(Executor master) {
+    return new Instance(master.getInstance(output));
+  }
+
+  /**
+   * Instance
+   * 
+   * @author Erich Schubert
+   */
+  private class Instance extends AbstractDoubleProcessor.Instance {
+    /**
+     * Constructor.
+     * 
+     * @param output Output variable
+     */
+    public Instance(SharedDouble.Instance output) {
+      super(output);
+    }
+
+    @Override
+    public void map(DBIDRef id) {
+      KNNList knn = knns.get(id);
+      double lrd = 0.0;
+      int size = 0;
+      for(DoubleDBIDListIter n = knn.iter(); n.valid(); n.advance()) {
+        // Do not include the query object
+        if(DBIDUtil.equal(n, id)) {
+          continue;
+        }
+        lrd += n.doubleValue();
+        size++;
+      }
+      // Avoid division by zero.
+      output.set(lrd > 0 ? size / lrd : 0);
+    }
+  }
+}
+\ No newline at end of file