[mlpack-svn] r14548 - mlpack/trunk/src/mlpack/core/tree/binary_space_tree

[fastlab-svn at coffeetalk-1.cc.gatech.edu]

Author: rcurtin
Date: 2013-03-13 16:46:41 -0400 (Wed, 13 Mar 2013)
New Revision: 14548

Modified:
   mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree.hpp
   mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree_impl.hpp
Log:
Cache furthest descendant distance.


Modified: mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree.hpp
===================================================================
--- mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree.hpp	2013-03-13 20:44:40 UTC (rev 14547)
+++ mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree.hpp	2013-03-13 20:46:41 UTC (rev 14548)
@@ -60,6 +60,8 @@
   StatisticType stat;
   //! The dimension this node split on if it is a parent.
   size_t splitDimension;
+  //! The distance to the furthest descendant, cached to speed things up.
+  double furthestDescendantDistance;
   //! The dataset.
   MatType& dataset;
 

Modified: mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree_impl.hpp
===================================================================
--- mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree_impl.hpp	2013-03-13 20:44:40 UTC (rev 14547)
+++ mlpack/trunk/src/mlpack/core/tree/binary_space_tree/binary_space_tree_impl.hpp	2013-03-13 20:46:41 UTC (rev 14548)
@@ -212,6 +212,7 @@
     bound(other.bound),
     stat(other.stat),
     splitDimension(other.splitDimension),
+    furthestDescendantDistance(other.furthestDescendantDistance),
     dataset(other.dataset)
 {
   // Create left and right children (if any).
@@ -384,9 +385,7 @@
 inline double BinarySpaceTree<BoundType, StatisticType, MatType>::
     FurthestDescendantDistance() const
 {
-  arma::vec centroid;
-  bound.Centroid(centroid);
-  return bound.MaxDistance(centroid);
+  return furthestDescendantDistance;
 }
 
 /**
@@ -443,6 +442,9 @@
   // We need to expand the bounds of this node properly.
   bound |= data.cols(begin, begin + count - 1);
 
+  // Calculate the furthest descendant distance.
+  furthestDescendantDistance = 0.5 * bound.Diameter();
+
   // Now, check if we need to split at all.
   if (count <= leafSize)
     return; // We can't split this.
@@ -493,6 +495,9 @@
   // We need to expand the bounds of this node properly.
   bound |= data.cols(begin, begin + count - 1);
 
+  // Calculate the furthest descendant distance.
+  furthestDescendantDistance = 0.5 * bound.Diameter();
+
   // First, check if we need to split at all.
   if (count <= leafSize)
     return; // We can't split this.