Package edu.cmu.tetrad.graph

Class Edges

java.lang.Object

edu.cmu.tetrad.graph.Edges

public final class Edges
extends Object

This factory class produces edges of the types commonly used for Tetrad-style graphs. For each method in the class, one supplies a pair of nodes, and an edge is returned, connecting those nodes, of the specified type. Methods are also included to help determine whether a specified edge falls into one of the types produced by this factory. It's entirely possible to produce edges of these types other than by using this factory. For randomUtil, an edge counts as a directed edge just in case it has one null endpoint and one arrow endpoint. Any edge which has one null endpoint and one arrow endpoint will do, whether or not this factory produced it. These helper methods provide a uniform way of testing whether an edge is in fact, e.g., a directed edge (or any of the other types).

Version:

$Id: $Id

Author:

josephramsey

Method Summary

Modifier and Type	Method	Description
static Edge	bidirectedEdge(Node nodeA, Node nodeB)	Constructs a new bidirected edge from nodeA to nodeB (<->).
static Edge	directedEdge(Node nodeA, Node nodeB)	Constructs a new directed edge from nodeA to nodeB (-->).
static Node	getDirectedEdgeHead(Edge edge)	For a directed edge, returns the node adjacent to the arrow endpoint.
static Node	getDirectedEdgeTail(Edge edge)	For a directed edge, returns the node adjacent to the null endpoint.
static boolean	isBidirectedEdge(Edge edge)	isBidirectedEdge.
static boolean	isDirectedEdge(Edge edge)	isDirectedEdge.
static boolean	isNondirectedEdge(Edge edge)	isNondirectedEdge.
static boolean	isPartiallyOrientedEdge(Edge edge)	isPartiallyOrientedEdge.
static boolean	isUndirectedEdge(Edge edge)	isUndirectedEdge.
static Edge	nondirectedEdge(Node nodeA, Node nodeB)	Constructs a new nondirected edge from nodeA to nodeB (o-o).
static Edge	partiallyOrientedEdge(Node nodeA, Node nodeB)	Constructs a new partially oriented edge from nodeA to nodeB (o->).
static void	sortEdges(List<Edge> edges)	sortEdges.
static Node	traverse(Node node, Edge edge)	If node is one endpoint of edge, returns the other endpoint.
static Node	traverseDirected(Node node, Edge edge)	For A -> B, given A, returns B; otherwise returns null.
static Node	traverseNondirected(Node node, Edge edge)	For A o-o B, given A, returns B; otherwise returns null.
static Node	traverseReverseDirected(Node node, Edge edge)	For A -> B, given B, returns A; otherwise returns null.
static Node	traverseSemiDirected(Node node, Edge edge)	For A --* B or A o-* B, given A, returns B.
static Edge	undirectedEdge(Node nodeA, Node nodeB)	Constructs a new undirected edge from nodeA to nodeB (--).

Methods inherited from class java.lang.Object

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

Method Details

bidirectedEdge

public static Edge bidirectedEdge(Node nodeA,
 Node nodeB)

Constructs a new bidirected edge from nodeA to nodeB (<->).

Parameters:

nodeA - a Node object

nodeB - a Node object

Returns:

a Edge object

directedEdge

public static Edge directedEdge(Node nodeA,
 Node nodeB)

Constructs a new directed edge from nodeA to nodeB (-->).

Parameters:

nodeA - a Node object

nodeB - a Node object

Returns:

a Edge object

partiallyOrientedEdge

public static Edge partiallyOrientedEdge(Node nodeA,
 Node nodeB)

Constructs a new partially oriented edge from nodeA to nodeB (o->).

Parameters:

nodeA - a Node object

nodeB - a Node object

Returns:

a Edge object

nondirectedEdge

public static Edge nondirectedEdge(Node nodeA,
 Node nodeB)

Constructs a new nondirected edge from nodeA to nodeB (o-o).

Parameters:

nodeA - a Node object

nodeB - a Node object

Returns:

a Edge object

undirectedEdge

public static Edge undirectedEdge(Node nodeA,
 Node nodeB)

Constructs a new undirected edge from nodeA to nodeB (--).

Parameters:

nodeA - a Node object

nodeB - a Node object

Returns:

a Edge object

isBidirectedEdge

public static boolean isBidirectedEdge(Edge edge)

isBidirectedEdge.

Parameters:

edge - a Edge object

Returns:

true iff an edge is a bidirected edge (<->).

isDirectedEdge

public static boolean isDirectedEdge(Edge edge)

isDirectedEdge.

Parameters:

edge - a Edge object

Returns:

true iff the given edge is a directed edge (-->).

isPartiallyOrientedEdge

public static boolean isPartiallyOrientedEdge(Edge edge)

isPartiallyOrientedEdge.

Parameters:

edge - a Edge object

Returns:

true iff the given edge is a partially oriented edge (o->)

isNondirectedEdge

public static boolean isNondirectedEdge(Edge edge)

isNondirectedEdge.

Parameters:

edge - a Edge object

Returns:

true iff some edge is an nondirected edge (o-o).

isUndirectedEdge

public static boolean isUndirectedEdge(Edge edge)

isUndirectedEdge.

Parameters:

edge - a Edge object

Returns:

true iff some edge is an undirected edge (-).

traverse

public static Node traverse(Node node,
 Edge edge)

If node is one endpoint of edge, returns the other endpoint.

Parameters:

node - The one endpoint.

edge - The edge

Returns:

The other endpoint.

traverseNondirected

public static Node traverseNondirected(Node node,
 Edge edge)

For A o-o B, given A, returns B; otherwise returns null.

Parameters:

node - The one endpoint.

edge - The edge

Returns:

The other endpoint.

traverseDirected

public static Node traverseDirected(Node node,
 Edge edge)

For A -> B, given A, returns B; otherwise returns null.

Parameters:

node - a Node object

edge - a Edge object

Returns:

a Node object

traverseReverseDirected

public static Node traverseReverseDirected(Node node,
 Edge edge)

For A -> B, given B, returns A; otherwise returns null.

Parameters:

node - a Node object

edge - a Edge object

Returns:

a Node object

traverseSemiDirected

public static Node traverseSemiDirected(Node node,
 Edge edge)

For A --* B or A o-* B, given A, returns B. For A <-* B, returns null. Added by ekorber, 2004/06/12.

Parameters:

node - a Node object

edge - a Edge object

Returns:

a Node object

getDirectedEdgeHead

public static Node getDirectedEdgeHead(Edge edge)

For a directed edge, returns the node adjacent to the arrow endpoint.

Parameters:

edge - a Edge object

Returns:

a Node object

Throws:

IllegalArgumentException - if the given edge is not a directed edge.

getDirectedEdgeTail

public static Node getDirectedEdgeTail(Edge edge)

For a directed edge, returns the node adjacent to the null endpoint.

Parameters:

edge - a Edge object

Returns:

a Node object

Throws:

IllegalArgumentException - if the given edge is not a directed edge.

sortEdges

public static void sortEdges(List<Edge> edges)

sortEdges.

Parameters:

edges - a List object