net.sf.oriented.pseudoline

Class EuclideanPseudoLines

java.lang.Object

net.sf.oriented.pseudoline.EuclideanPseudoLines

public class EuclideanPseudoLines
extends Object

This class takes a rank 3 oriented matroid and prepares it for processing from a Euclidean perspective. The origin is forced to be near the line at infinity (i.e. in an unbounded face). One of the lines is chosen as the line at infinity, and a face lying on that line is chosen as the positive face, and the oriented matroid may need reorienting to make that face actually be the positive face.

Author:

jeremycarroll

Constructor Summary

Constructors

Constructor and Description
EuclideanPseudoLines(OM om, Label infinity) Prepare the given oriented matroid for Euclidean processing, with the given line at infinity.
EuclideanPseudoLines(OM om, String infinity, String... alsoReorient) Prepare the given oriented matroid for Euclidean processing, with the given line at infinity, and a hint, which may or may not be followed, concerning which lines to re-orient.

Method Summary

Methods

Modifier and Type	Method and Description
PseudoLineDrawing	asDrawing() Prepare to draw this arrangement of pseudolines.
OM	getEquivalentOM() This is the oriented matroid which is actually being processed.
Label	getInfinity() This is the element at infinity as from the constructor.
Permutation	getPermutation() The elements of the original oriented matroid are permuted in the equivalent oriented matroid.
Label[]	getReorientation() This is the set of elements which were reoriented in the processing of this class.
void	switchFaceLattice() This method impacts performance.
String[]	toCrossingsString() Gives a representation of the modified oriented matroid as a list of crossings strings that can be used in FactoryFactory.fromCrossings(String...)

Methods inherited from class java.lang.Object

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

Constructor Detail

EuclideanPseudoLines

public EuclideanPseudoLines(OM om,
                    String infinity,
                    String... alsoReorient)

Prepare the given oriented matroid for Euclidean processing, with the given line at infinity, and a hint, which may or may not be followed, concerning which lines to re-orient.

Parameters:

om - The oriented matroid to process

infinity - Project this element to be the line at infinity

alsoReorient - reorient these elements too, before processing. To find which elements are actually reoriented you must call getReorientation()

Throws:

NotRank3Exception - If om is not of rank 3.

EuclideanPseudoLines

public EuclideanPseudoLines(OM om,
                    Label infinity)

Prepare the given oriented matroid for Euclidean processing, with the given line at infinity.

Parameters:

om - The oriented matroid to process

infinity - Project this element to be the line at infinity

Throws:

NotRank3Exception - If om is not of rank 3.

Method Detail

asDrawing

public PseudoLineDrawing asDrawing()
                            throws CoLoopCannotBeDrawnException

Prepare to draw this arrangement of pseudolines.

Returns:

A drawing from which an image can be constructed.

Throws:

CoLoopCannotBeDrawnException - If one of the elements other than infinity is a co-loop.

switchFaceLattice

public void switchFaceLattice()

This method impacts performance. Calling it may make your program faster, or it may make it slower. It is unlikely to leave the performance unchanged. Computing the face lattice is expensive. The algorithms need to compute the face lattice of the original oriented matroid; it may be more efficient to recompute the face lattice for the modified oriented matroid too, or it may not. Invoking this method does that recomputation.

toCrossingsString

public String[] toCrossingsString()

Gives a representation of the modified oriented matroid as a list of crossings strings that can be used in FactoryFactory.fromCrossings(String...)

Returns:

A list of crossing strings.

See Also:

getEquivalentOM()

getEquivalentOM

public OM getEquivalentOM()

This is the oriented matroid which is actually being processed. This is a reorientaiton of the oriented matroid passed to the constructor.

Returns:

An equivalent oriented matroid

See Also:

EuclideanPseudoLines(OM, String, String...), EuclideanPseudoLines(OM, Label), getReorientation()

getReorientation

public Label[] getReorientation()

This is the set of elements which were reoriented in the processing of this class.

Returns:

A list of elements reoriented for processing as a Euclidean arrangement of Psuedolines

See Also:

EuclideanPseudoLines(OM, String, String...), EuclideanPseudoLines(OM, Label), getEquivalentOM()

getPermutation

public Permutation getPermutation()

The elements of the original oriented matroid are permuted in the equivalent oriented matroid. This method gives access to the permutation.

Returns:

The permutation of the elements between the original oriented matroid, and the one used for processing as a Euclidean arrangement of Psuedolines

getInfinity

public Label getInfinity()

This is the element at infinity as from the constructor.

Returns:

The element at infinity.

See Also:

EuclideanPseudoLines(OM, String, String...), EuclideanPseudoLines(OM, Label)