edu.stanford.math.plex

Class WitnessStream

java.lang.Object

edu.stanford.math.plex.SimplexStream

edu.stanford.math.plex.WitnessStream

All Implemented Interfaces:

java.lang.Iterable<Simplex>, java.util.Iterator<Simplex>

public class WitnessStream
extends SimplexStream

A WitnessStream is an iterable Witness complex.

A WitnessStream is a SimplexStream whose elements are the simplices of the Witness complex of a PointData instance. That is, a simplex is added to the complex only each face is present and a witness is found for the entire simplex. The details of this construction are described in Topological estimation using witness complexes, Vin de Silva and Gunnar Carlsson, Symposium on Point-Based Graphics, ETH, Zurich, Switzerland, June 2-4, 2004.

Version:

$Id$

See Also:

LazyWitnessStream

Nested Class Summary

Nested classes/interfaces inherited from class edu.stanford.math.plex.SimplexStream

SimplexStream.ComparisonType, SimplexStream.Head, SimplexStream.Stack, SimplexStream.Tail

Field Summary

Fields

Modifier and Type	Field and Description
protected double	granularity
protected int[]	landmarks
protected int	maxDimension
protected double	maxR
protected PointData	pdata
protected SimplexStream.Stack	stack

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	WitnessStream()

Method Summary

Methods

Modifier and Type	Method and Description
double	convert_filtration_index(int fi) Convert a filtration index into a persistence parameter (i.e., double) -- gets overloaded by some subclasses.
static double	estimateRmax(PointData data, int[] landmarks) Estimate Rmax for a given PointData and landmark set.
protected SimplexStream.Stack	find_simplices(double delta, double R_max, int max_dimension, int[] landmarks, PointData data)
boolean	hasNext() Is there a next Simplex in the stream?
java.util.Iterator<Simplex>	iterator() Make an iterator for the stream.
protected static int	m_index(int n, int k, int N)
static int[]	makeRandomLandmarks(PointData data, int L) Randomly choose a subset of a given PointData for use as landmarks.
int	maxDimension() Max dimension of simplices in the stream.
Simplex	next() Next Simplex in the stream.
int	size() How many simplices are in the stream?

Methods inherited from class edu.stanford.math.plex.SimplexStream

convertInterval, convertInterval, remove, verify

Methods inherited from class java.lang.Object

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

Field Detail

pdata

protected final PointData pdata

granularity

protected final double granularity

maxDimension

protected final int maxDimension

landmarks

protected final int[] landmarks

maxR

protected double maxR

stack

protected SimplexStream.Stack stack

Constructor Detail

WitnessStream

protected WitnessStream()

Method Detail

makeRandomLandmarks

public static int[] makeRandomLandmarks(PointData data,
                        int L)

Randomly choose a subset of a given PointData for use as landmarks.

Parameters:

data - PointData from which to choose landmarks.

L - number of landmarks to choose.

Returns:

An int[] containing indices of the landmarks.

estimateRmax

public static double estimateRmax(PointData data,
                  int[] landmarks)

Estimate Rmax for a given PointData and landmark set.

Parameters:

data - The entire data set.

landmarks - The landmark set.

Returns:

The max/min of the landmarks to points distances.

hasNext

public boolean hasNext()

Is there a next Simplex in the stream?

Specified by:

hasNext in interface java.util.Iterator<Simplex>

Specified by:

hasNext in class SimplexStream

Returns:

Return true if the stream is not yet empty.

next

public Simplex next()

Next Simplex in the stream.

Specified by:

next in interface java.util.Iterator<Simplex>

Specified by:

next in class SimplexStream

Returns:

Return the smallest remaining Simplex instance.

size

public int size()

How many simplices are in the stream?

Specified by:

size in class SimplexStream

Returns:

The number of simplices in the stream.

maxDimension

public int maxDimension()

Max dimension of simplices in the stream.

Specified by:

maxDimension in class SimplexStream

Returns:

Max dimension of simplices in the stream.

convert_filtration_index

public double convert_filtration_index(int fi)

Convert a filtration index into a persistence parameter (i.e., double) -- gets overloaded by some subclasses.

Overrides:

convert_filtration_index in class SimplexStream

Parameters:

fi - Filtration index to convert.

Returns:

double persistence parameter.

iterator

public java.util.Iterator<Simplex> iterator()

Make an iterator for the stream.

Returns:

Iterator instance for the stream.

See Also:

Iterator

m_index

protected static int m_index(int n,
          int k,
          int N)

find_simplices

protected SimplexStream.Stack find_simplices(double delta,
                                 double R_max,
                                 int max_dimension,
                                 int[] landmarks,
                                 PointData data)