mobios.index
Class VPKNNCursor

java.lang.Object
  mobios.index.Cursor
      mobios.index.VPKNNCursor

All Implemented Interfaces:

Iterator

public class VPKNNCursor
extends Cursor

Implements an Cursor, for KNN search in vp tree

Version:

2006.07.09

Author:

Weijia Xu

Constructor Summary

VPKNNCursor(KNNQuery query, Index index)

Method Summary

void	getCachedResult() Gets the results that have been cached based on current search stratagey, target radius and search status.
int[]	getCounters() return some counters
int[]	getDistanceCalculationNumber() return the number of distance calculations during the search
int	getHeight()
int[][]	getLevelNodeVisited() return the number of nodes visited in each level of the index tree.
int[][]	getLevelPointVisited() return the number of data objects that the query directly compute distance with in the leaf nodes of each level of the index tree.
int[]	getNodeVisitedNumber() Return the number of index node visited during the search
double[][]	getQueryPivotDistance() return the average distance between the query and the pivots for each layer.
void	queueResults(IndexObject obj, double distance) Queue the results found during the search
String	toString()

Methods inherited from class mobios.index.Cursor

hasNext, next, remove

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

VPKNNCursor

public VPKNNCursor(KNNQuery query,
                   Index index)

Parameters:

query -

index -

Method Detail

getHeight

public int getHeight()

Returns:

the height the of index tree

getNodeVisitedNumber

public int[] getNodeVisitedNumber()

Return the number of index node visited during the search

Returns:

an int array of length 2, the first element is the total number of index nodes visited during the search, the second is the number of internal nodes visited.

getCounters

public int[] getCounters()

return some counters

Returns:

an array of counters: 0: int resultConfirmedByPathDist; //number of data points that are confirmed to be results by path distance list //without computing the distance directly. it is a subset of resultWithoutDist. 1: int pointPrunedByPivotDist; //number of data points that are pruned by the pivot distance 2: int nodePrunedByPivotDist; //number of nodes that are pruned by the pivot distance 3: int pointPrunedByPathDist; //number of data points that are pruned by path distance list 4: int nodeWithoutDist; //number of nodes that are determined to be all results without computing distance directly. 5: int resultWithoutDist; //number of results that are determined to be results without computing distance directly. 6: int pivotAsResult; //number of pivots that are also search results 7: int pivotRowIDAsResult; //number of row IDs corresponding to those pivots being search results

getDistanceCalculationNumber

public int[] getDistanceCalculationNumber()

return the number of distance calculations during the search

Returns:

an int array of length 2, the first element is total number of distance calculations during the search, the second is the number of distance calculations between the query and the pivots

getQueryPivotDistance

public double[][] getQueryPivotDistance()

return the average distance between the query and the pivots for each layer.

Returns:

a 2-d double array, average distance between the query to the pivots (column) on each level (row). the length of a row is the max number of pivots in the level.

getLevelNodeVisited

public int[][] getLevelNodeVisited()

return the number of nodes visited in each level of the index tree.

Returns:

a 2-d int array, each row is the statistics of a level, starting from level 0, the root. each row is an int array of length 2, the first is the number of index nodes of the level that belong to the parent nodes of the nodes counted; the second is the number of nodes visited in the layer,

getLevelPointVisited

public int[][] getLevelPointVisited()

return the number of data objects that the query directly compute distance with in the leaf nodes of each level of the index tree.

Returns:

a 2-d int array, each row is the statistics of a level, starting from level 0, the root. each row is an int array of length 2, the first the total number of data objects in the leaf node visited of the level, the second is the number of data object that the query directly compute distance with. Note that the total number of index nodes of a level can not be found during the search. Also note that the first element can be 0.

toString

public String toString()

Overrides:

toString in class Object

Returns:

a string representation of the Visitor

queueResults

public void queueResults(IndexObject obj,
                         double distance)

Queue the results found during the search

Parameters:

obj - matching object

distance - distance of this matches

getCachedResult

public void getCachedResult()

Gets the results that have been cached based on current search stratagey, target radius and search status. move qulaified results from cahcedResults to result.