Module org.jgrapht.io
Package org.jgrapht.nio.graph6

Class Graph6Sparse6Importer<V,E>

java.lang.Object
org.jgrapht.nio.BaseEventDrivenImporter<V,E>
org.jgrapht.nio.graph6.Graph6Sparse6Importer<V,E>
Type Parameters:
V - graph vertex type
E - graph edge type
All Implemented Interfaces:
GraphImporter<V,E>
public class Graph6Sparse6Importer<V,E> extends BaseEventDrivenImporter<V,E> implements GraphImporter<V,E>
Importer which reads graphs in graph6 or sparse6 format.

A description of the format can be found here. graph6 and sparse6 are formats for storing undirected graphs in a compact manner, using only printable ASCII characters. Files in these formats have text format and contain one line per graph. graph6 is suitable for small graphs, or large dense graphs. sparse6 is more space-efficient for large sparse graphs. Typically, files storing graph6 graphs have the 'g6' extension. Similarly, files storing sparse6 graphs have a 's6' file extension. sparse6 graphs support loops and multiple edges, graph6 graphs do not.

Note that a g6/s6 string may contain backslashes '\'. Thus, escaping is required. E.g. 

 ":?@MnDA\oi"
may result in undefined behavior. This should have been: 
 ":?@MnDA\\oi"

The graph vertices and edges are build using the corresponding graph suppliers. The id of the vertices in the original file are reported as a vertex attribute named "ID". Note, however, that in this file format the identifiers from the input files are always going to be integers starting from zero, as the format does not retain such information in order to achieve compactness.

The default behavior of the importer is to use the graph vertex supplier in order to create vertices. The user can also bypass vertex creation by providing a custom vertex factory method using setVertexFactory(Function). The factory method is responsible to create a new graph vertex given the vertex identifier read from file.

Author:
Dimitrios Michail

  • Field Details

    • DEFAULT_VERTEX_ID_KEY

      public static final String DEFAULT_VERTEX_ID_KEY
      Default key used for vertex ID.
      See Also:

  • Constructor Details

    • Graph6Sparse6Importer

      public Graph6Sparse6Importer()
      Construct a new importer

  • Method Details

    • getVertexFactory

      public Function<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(Function<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, Reader input)
      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.

      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