Module org.jgrapht.io

Package org.jgrapht.nio.dimacs

Class DIMACSImporter<V,E>

java.lang.Object

org.jgrapht.nio.BaseEventDrivenImporter<V,E>

org.jgrapht.nio.dimacs.DIMACSImporter<V,E>

Type Parameters:

V - the graph vertex type

E - the graph edge type

All Implemented Interfaces:

GraphImporter<V,E>

public class DIMACSImporter<V,E>
extends BaseEventDrivenImporter<V,E>
implements GraphImporter<V,E>

Imports a graph specified in DIMACS format.

See DIMACSFormat for a description of all the supported DIMACS formats.

In summary, one of the most common DIMACS formats was used in the 2nd DIMACS challenge and follows the following structure:

 
 DIMACS G {
    c <comments> ignored during parsing of the graph
    p edge <number of nodes> <number of edges>
    e <edge source 1> <edge target 1>
    e <edge source 2> <edge target 2>
    e <edge source 3> <edge target 3>
    e <edge source 4> <edge target 4>
    ...
 }
 
 

Although not specified directly in the DIMACS format documentation, this implementation also allows for the a weighted variant:

 
 e <edge source 1> <edge target 1> <edge_weight> 
 
 

Note: the current implementation does not fully implement the DIMACS specifications! Special (rarely used) fields specified as 'Optional Descriptors' are currently not supported (ignored).

Author:

Michael Behrisch (adaptation of GraphReader class), Joris Kinable, Dimitrios Michail

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.String	DEFAULT_VERTEX_ID_KEY	Default key used for vertex ID.

Constructor Summary

Constructors

Constructor	Description
DIMACSImporter()	Construct a new DIMACSImporter
DIMACSImporter(double defaultWeight)	Construct a new DIMACSImporter

Method Summary

Modifier and Type	Method	Description
java.util.function.Function<java.lang.Integer,V>	getVertexFactory()	Get the user custom vertex factory.
void	importGraph(Graph<V,E> graph, java.io.Reader input)	Import a graph.
void	setVertexFactory(java.util.function.Function<java.lang.Integer,V> vertexFactory)	Set the user custom vertex factory.

Methods inherited from class org.jgrapht.nio.BaseEventDrivenImporter

addEdgeAttributeConsumer, addEdgeConsumer, addEdgeCountConsumer, addGraphAttributeConsumer, addImportEventConsumer, addVertexAttributeConsumer, addVertexConsumer, addVertexCountConsumer, notifyEdge, notifyEdgeAttribute, notifyEdgeCount, notifyGraphAttribute, notifyImportEvent, notifyVertex, notifyVertexAttribute, notifyVertexCount, removeEdgeAttributeConsumer, removeEdgeConsumer, removeEdgeCountConsumer, removeGraphAttributeConsumer, removeImportEventConsumer, removeVertexAttributeConsumer, removeVertexConsumer, removeVertexCountConsumer

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jgrapht.nio.GraphImporter

importGraph, importGraph

Field Detail

DEFAULT_VERTEX_ID_KEY

public static final java.lang.String DEFAULT_VERTEX_ID_KEY

Default key used for vertex ID.

See Also:

Constant Field Values

Constructor Detail

DIMACSImporter

public DIMACSImporter(double defaultWeight)

Construct a new DIMACSImporter

Parameters:

defaultWeight - default edge weight

DIMACSImporter

public DIMACSImporter()

Construct a new DIMACSImporter

Method Detail

getVertexFactory

public java.util.function.Function<java.lang.Integer,V> getVertexFactory()

Get the user custom vertex factory. This is null by default and the graph supplier is used instead.

Returns:

the user custom vertex factory

setVertexFactory

public void setVertexFactory(java.util.function.Function<java.lang.Integer,V> vertexFactory)

Set the user custom vertex factory. The default behavior is being null in which case the graph vertex supplier is used. If supplied the vertex factory is called every time a new vertex is encountered in the file. The method is called with parameter the vertex identifier from the file and should return the actual graph vertex to add to the graph.

Parameters:

vertexFactory - a vertex factory

importGraph

public void importGraph(Graph<V,E> graph,
                        java.io.Reader input)
                 throws ImportException

Import a graph.

The provided graph must be able to support the features of the graph that is read. For example if the file contains self-loops then the graph provided must also support self-loops. The same for multiple edges.

If the provided graph is a weighted graph, the importer also reads edge weights. Otherwise edge weights are ignored.

Specified by:

importGraph in interface GraphImporter<V,E>

Parameters:

graph - the output graph

input - the input reader

Throws:

ImportException - in case an error occurs, such as I/O or parse error