com.eatthepath.jvptree

Interface ThresholdSelectionStrategy<P,E extends P>

All Known Implementing Classes:

MedianDistanceThresholdSelectionStrategy, SamplingMedianDistanceThresholdSelectionStrategy

public interface ThresholdSelectionStrategy<P,E extends P>

A strategy for choosing a distance threshold for vp-tree nodes. The main feature of vp-trees is that they partition collections of points into collections of points that are closer to a given point (the vantage point) than a certain threshold or farther away from the vantage point than the threshold. Given a list of points, a ThresholdSelectionStrategy chooses the distance that will be used by a vp-tree node to partition its points.

Author:

Jon Chambers

Method Summary

Modifier and Type	Method and Description
double	selectThreshold(List<E> points, P origin, DistanceFunction<P> distanceFunction) Chooses a partitioning distance threshold appropriate for the given list of points.

Method Detail

selectThreshold

double selectThreshold(List<E> points,
                       P origin,
                       DistanceFunction<P> distanceFunction)

Chooses a partitioning distance threshold appropriate for the given list of points. Implementations are allowed to reorder the list of points, but must not add or remove points from the list.

Parameters:

points - the points for which to choose a partitioning distance threshold

origin - the point from which the threshold distances should be calculated

distanceFunction - the function to be used to calculate distances between points

Returns:

a partitioning threshold distance appropriate for the given list of points; ideally, some points should be closer to the origin than the returned threshold, and some should be farther