edu.stanford.math.plex4.metric.utility

Class MetricUtility

java.lang.Object

edu.stanford.math.plex4.metric.utility.MetricUtility

public class MetricUtility
extends java.lang.Object

This class contains various functions for dealing with metric spaces.

Author:

Andrew Tausz

Constructor Summary

Constructors

Constructor and Description
MetricUtility()

Method Summary

Methods

Modifier and Type	Method and Description
static double[]	computeCentroid(AbstractObjectMetricSpace<double[]> metricSpace) This function computes the centroid of the set of points within the metric space.
static double[]	computeMaxima(AbstractObjectMetricSpace<double[]> metricSpace) This function computes the coordinate-wise maxima of a given Euclidean metric space.
static double[]	computeMinima(AbstractObjectMetricSpace<double[]> metricSpace) This function computes the coordinate-wise minima of a given Euclidean metric space.
static double	estimateDiameter(AbstractIntMetricSpace metricSpace) This function performs randomized sampling to find the estimated diameter of the given metric space.
static double	estimateDiameter(AbstractIntMetricSpace metricSpace, int trials) This function estimates the diameter of the supplied metric space.
static <T> int[]	filterByNeighborDistance(AbstractSearchableMetricSpace<T> metricSpace, int k, double proportion)
static double[]	getAllDistances(AbstractIntMetricSpace metricSpace, int index)
static <T> double[]	getKthNearestNeighborDistances(AbstractSearchableMetricSpace<T> metricSpace, int k)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MetricUtility

public MetricUtility()

Method Detail

estimateDiameter

public static double estimateDiameter(AbstractIntMetricSpace metricSpace,
                      int trials)

This function estimates the diameter of the supplied metric space. The diameter is defined as the smallest number r such that d(x, y) <= r for all x, y in the space. The estimate is obtained by randomly choosing pairs (i, j), and taking the maximum distance over all pairs.

Parameters:

metricSpace - the metric space to estimate the diameter of

trials - the number of random pairs to choose

Returns:

an estimate of the diameter of the metric space

estimateDiameter

public static double estimateDiameter(AbstractIntMetricSpace metricSpace)

This function performs randomized sampling to find the estimated diameter of the given metric space. It uses a default number of samples equal to 100.

Parameters:

metricSpace - the metric space to estimate the diameter of

Returns:

an estimate of the diameter of the metric space

computeMaxima

public static double[] computeMaxima(AbstractObjectMetricSpace<double[]> metricSpace)

This function computes the coordinate-wise maxima of a given Euclidean metric space.

Parameters:

metricSpace - the metric space to compute the maxima for

Returns:

the componentwise minima of the elements of the metric space

computeMinima

public static double[] computeMinima(AbstractObjectMetricSpace<double[]> metricSpace)

This function computes the coordinate-wise minima of a given Euclidean metric space.

Parameters:

metricSpace - the metric space to compute the minima for

Returns:

the componentwise minima of the elements of the metric space

computeCentroid

public static double[] computeCentroid(AbstractObjectMetricSpace<double[]> metricSpace)

This function computes the centroid of the set of points within the metric space.

Parameters:

metricSpace - the metric space to compute the centroid of

Returns:

the centroid of the given metric space

getAllDistances

public static double[] getAllDistances(AbstractIntMetricSpace metricSpace,
                       int index)

getKthNearestNeighborDistances

public static <T> double[] getKthNearestNeighborDistances(AbstractSearchableMetricSpace<T> metricSpace,
                                          int k)

filterByNeighborDistance

public static <T> int[] filterByNeighborDistance(AbstractSearchableMetricSpace<T> metricSpace,
                                 int k,
                                 double proportion)