gum::Arc Class Reference

The base class for all directed edges. More...

#include <graphElements.h>

Public Member Functions
Constructors / Destructors
	Arc (NodeId tail, NodeId head)
	basic constructor. Creates tail -> head.
	Arc (const Arc &src)
	copy constructor
	~Arc ()
	destructor
Accessors
GUM_NODISCARD NodeId	tail () const
	returns the tail of the arc
GUM_NODISCARD NodeId	head () const
	returns the head of the arc
GUM_NODISCARD NodeId	other (NodeId id) const
	returns an extremal node of an edge given the ID of the other one
GUM_NODISCARD NodeId	first () const
	returns one extremal node ID (whichever one it is is unspecified)
GUM_NODISCARD NodeId	second () const
	returns the node ID of the other extremal node ID
Operators
Arc &	operator= (const Arc &src)
	copy operator
bool	operator== (const Arc &src) const =default
	checks whether two arcs are equal

Private Member Functions
void	_setTail_ (NodeId id)
	modifies the tail of the arc
void	_setHead_ (NodeId id)
	modifies the head of the arc
void	operator- ()
	reverses the direction of the arc

Private Attributes
NodeId	n1
	the extremal nodes of the edge (their order is unimportant)
NodeId	n2

Detailed Description

The base class for all directed edges.

This class is used as a basis for manipulating all directed edges (i.e., edges in which the order of the nodes is meaningful). For instance, in an arrow, one node is near the head and the other one is farther, hence these nodes have different status and swapping the nodes results in reversing the direction of the arrow. Thus, the nodes in an arrow can be thought of as asymmetric and the arrow's graphical representation contains a pointed extremity so as to account for this asymmetry. In aGrUM, the latter is taken into account by Arc.

Usage example:

// creation of an arc (directed edge) from 3 to 4
Arc arc1 (3,4);
  *
// compare two arcs
if (Arc(3,4) != Arc(4,3)) cerr << "ok, this is asymmetric" << endl;
 
// get the extremities of the edge
cerr << arc1.tail() << " = 3 and " << arc1.head() << " = 4\n";
cerr << "arc1 = (3 -> " << edge1.other (3) << ")" << endl;
 
// display an arc in a console
cerr << arc1 << endl;

Definition at line 261 of file graphElements.h.

Constructor & Destructor Documentation

Arc() [1/2]

gum::Arc::Arc	(	NodeId	tail,
		NodeId	head )

basic constructor. Creates tail -> head.

Warning

the order in which the nodes are passed is important

References head(), and tail().

Referenced by Arc(), operator=(), and operator==().

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Arc() [2/2]

gum::Arc::Arc

(

const Arc &

src

)

copy constructor

References Arc().

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~Arc()

gum::Arc::~Arc

(

)

destructor

Member Function Documentation

_setHead_()

void gum::Arc::_setHead_ ( NodeId id )

private

modifies the head of the arc

_setTail_()

void gum::Arc::_setTail_ ( NodeId id )

private

modifies the tail of the arc

first()

GUM_NODISCARD NodeId gum::Arc::first

(

)

const

returns one extremal node ID (whichever one it is is unspecified)

References GUM_NODISCARD.

Referenced by gum::BarrenNodesFinder::barrenNodes().

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head()

GUM_NODISCARD NodeId gum::Arc::head

(

)

const

returns the head of the arc

References GUM_NODISCARD.

Referenced by Arc(), gum::BarrenNodesFinder::barrenNodes(), gum::ArcGraphPart::eraseArc(), gum::BayesNet< GUM_SCALAR >::eraseArc(), gum::InfluenceDiagram< GUM_SCALAR >::eraseArc(), gum::DAGCycleDetector::hasCycleFromModifications(), and gum::BayesNet< GUM_SCALAR >::reverseArc().

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operator-()

void gum::Arc::operator- ( )

private

reverses the direction of the arc

operator=()

Arc & gum::Arc::operator=

(

const Arc &

src

)

copy operator

References Arc().

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operator==()

bool gum::Arc::operator== ( const Arc & src ) const

default

checks whether two arcs are equal

Two arcs are considered equal if they have the same head and tail (by same we mean they have the same ID).

References Arc().

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other()

GUM_NODISCARD NodeId gum::Arc::other

(

NodeId

id

)

const

returns an extremal node of an edge given the ID of the other one

References GUM_NODISCARD.

second()

GUM_NODISCARD NodeId gum::Arc::second

(

)

const

returns the node ID of the other extremal node ID

References GUM_NODISCARD.

tail()

GUM_NODISCARD NodeId gum::Arc::tail

(

)

const

returns the tail of the arc

References GUM_NODISCARD.

Referenced by Arc(), gum::BarrenNodesFinder::barrenNodes(), gum::ArcGraphPart::eraseArc(), gum::BayesNet< GUM_SCALAR >::eraseArc(), gum::InfluenceDiagram< GUM_SCALAR >::eraseArc(), gum::DAGCycleDetector::hasCycleFromModifications(), and gum::BayesNet< GUM_SCALAR >::reverseArc().

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Member Data Documentation

n1

NodeId gum::Arc::n1

private

the extremal nodes of the edge (their order is unimportant)

Definition at line 319 of file graphElements.h.

n2

NodeId gum::Arc::n2

private

Definition at line 320 of file graphElements.h.

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The documentation for this class was generated from the following file:

• agrum/base/graphs/graphElements.h