[mlpack-svn] r16220 - mlpack/trunk/src/mlpack/core/tree

fastlab-svn at coffeetalk-1.cc.gatech.edu fastlab-svn at coffeetalk-1.cc.gatech.edu
Thu Feb 6 15:08:59 EST 2014


Author: rcurtin
Date: Thu Feb  6 15:08:58 2014
New Revision: 16220

Log:
TraversalInfo, a new idea for doing things.  This will need to be further
documented...


Added:
   mlpack/trunk/src/mlpack/core/tree/traversal_info.hpp

Added: mlpack/trunk/src/mlpack/core/tree/traversal_info.hpp
==============================================================================
--- (empty file)
+++ mlpack/trunk/src/mlpack/core/tree/traversal_info.hpp	Thu Feb  6 15:08:58 2014
@@ -0,0 +1,85 @@
+/**
+ * @file traversal_info.hpp
+ * @author Ryan Curtin
+ *
+ * This class will hold the traversal information for dual-tree traversals.  A
+ * dual-tree traversal should be updating the members of this class before
+ * Score() is called.
+ */
+#ifndef __MLPACK_CORE_TREE_TRAVERSAL_INFO_HPP
+#define __MLPACK_CORE_TREE_TRAVERSAL_INFO_HPP
+
+/**
+ * The TraversalInfo class holds traversal information which is used in
+ * dual-tree (and single-tree) traversals.  A traversal should be updating the
+ * members of this class before Score() is called.  This class should be held as
+ * a member of the RuleType class and the interface to it should be through a
+ * TraversalInfo() method.
+ *
+ * The information held by this class is the last node combination visited
+ * before the current node combination was recursed into, and the score
+ * resulting from when Score() was called on that combination.  However, this
+ * information is identical for a query node and a reference node in a
+ * particular node combination, so traversals only need to update the
+ * TraversalInfo object in a query node (and the algorithms should only use the
+ * TraversalInfo object from a query node).
+ *
+ * In general, this auxiliary traversal information is used to try and make a
+ * prune without needing to call BaseCase() or calculate the distance between
+ * nodes.  Using this information you can place bounds on the distance between
+ * the two nodes quickly.
+ *
+ * If the traversal is not updating the members of this class correctly, a
+ * likely result is a null pointer dereference.  Dual-tree algorithms should
+ * assume that the members are set properly and should not need to check for
+ * null pointers.
+ *
+ * There is one exception, which is the root node combination; the score can be
+ * set to 0 and the query and reference nodes can just be set to the root nodes;
+ * no algorithm should be able to prune the root combination anyway.
+ */
+template<typename TreeType>
+class TraversalInfo
+{
+ public:
+  /**
+   * Create the TraversalInfo object and initialize the pointers to NULL.
+   */
+  TraversalInfo() :
+    lastQueryNode(NULL),
+    lastReferenceNode(NULL),
+    lastScore(0.0),
+    lastBaseCase(0.0) { /* Nothing to do. */ }
+
+  //! Get the last query node.
+  TreeType* LastQueryNode() const { return lastQueryNode; }
+  //! Modify the last query node.
+  TreeType*& LastQueryNode() { return lastQueryNode; }
+
+  //! Get the last reference node.
+  TreeType* LastReferenceNode() const { return lastReferenceNode; }
+  //! Modify the last reference node.
+  TreeType*& LastReferenceNode() { return lastReferenceNode; }
+
+  //! Get the score associated with the last query and reference nodes.
+  double LastScore() const { return lastScore; }
+  //! Modify the score associated with the last query and reference nodes.
+  double& LastScore() { return lastScore; }
+
+  //! Get the base case associated with the last node combination.
+  double LastBaseCase() const { return lastBaseCase; }
+  //! Modify the base case associated with the last node combination.
+  double& LastBaseCase() { return lastBaseCase; }
+
+ private:
+  //! The last query node.
+  TreeType* lastQueryNode;
+  //! The last reference node.
+  TreeType* lastReferenceNode;
+  //! The last score.
+  double lastScore;
+  //! The last base case.
+  double lastBaseCase;
+};
+
+#endif



More information about the mlpack-svn mailing list