edu.stanford.math.plex

Class LazyWitnessStream

java.lang.Object

edu.stanford.math.plex.SimplexStream

edu.stanford.math.plex.LazyWitnessStream

All Implemented Interfaces:

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

public class LazyWitnessStream
extends SimplexStream

A LazyWitnessStream is a SimplexStream whose elements are the simplices of the lazy Witness complex of a PointData instance. The implementation is very similar to the RipsStream, and in fact the results are analogous for nu=0. 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:

RipsStream, WitnessStream

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[]	finite_eij_array
double	granularity
int[]	landmarks
int	maxDimension
protected double	maxR
int	nu
PointData	pdata
protected SimplexStream.Stack	stack

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LazyWitnessStream()

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.
protected SimplexStream.Stack	find_simplices(double delta, double R_max, int nu, 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.
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

public final PointData pdata

granularity

public final double granularity

maxDimension

public final int maxDimension

landmarks

public final int[] landmarks

nu

public final int nu

maxR

protected double maxR

finite_eij_array

protected double[] finite_eij_array

stack

protected SimplexStream.Stack stack

Constructor Detail

LazyWitnessStream

protected LazyWitnessStream()

Method Detail

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

find_simplices

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