Package org.graphstream.algorithm.generator

Class WattsStrogatzGenerator

java.lang.Object
org.graphstream.stream.SourceBase
org.graphstream.algorithm.generator.BaseGenerator
org.graphstream.algorithm.generator.WattsStrogatzGenerator
All Implemented Interfaces:
Generator, org.graphstream.stream.Source
public class WattsStrogatzGenerator
extends BaseGenerator
A generator following the small-world model of Watts and Strogatz.

This generator creates small-world graphs of arbitrary size.

This model generates a ring of n nodes where each node is connected to its k nearest neighbours in the ring (k/2 on each side, which means k must be even). Then it process each node of the ring in order following the ring, and "rewiring" each of their edges toward the not yet processed nodes with randomly chosen nodes with a probability beta.

Usage

You must provide values for n, k and beta at construction time. You must ensure that k is event, that n >> k >> log(n) >> 1. Furthermore, beta being a probability it must be between 0 and 1.

By default, the generator will produce a placement for nodes using the ``xyz`` attribute.

This generator will produce the ring of nodes once begin() has been called. Then calling nextEvents() will rewire one node at a time return true until each node is processed, in which case it returns false. You must then call end().

Example

 Graph graph = new SingleGraph("This is a small world!");
 Generator gen = new WattsStrogatzGenerator(20, 2, 0.5);
 
 gen.addSink(graph);
 gen.begin();
 while(gen.nextEvents()) {}
 gen.end();
 
 graph.display(false); // Node position is provided.

Reference

This generator is based on the Watts-Strogatz model.

Scientific Reference :
Watts, D.J. and Strogatz, S.H. "Collective dynamics of 'small-world' networks". Nature 393 (6684): 409–10. doi:10.1038/30918. PMID 9623998. 1998.

  • Nested Class Summary

    Nested classes/interfaces inherited from class org.graphstream.stream.SourceBase

    org.graphstream.stream.SourceBase.ElementType

  • Constructor Summary

    Constructors 
    Constructor Description
    WattsStrogatzGenerator​(int n, int k, double beta)
    New Watts-Strogatz generator.

  • Method Summary

    Modifier and Type Method Description
    void begin()
    Begin the graph generation.
    void end()
    End the graph generation by finalizing it.
    boolean nextEvents()
    Perform the next step in generating the graph.

    Methods inherited from class org.graphstream.algorithm.generator.BaseGenerator

    addEdgeAttribute, addEdgeAttribute, addEdgeAttribute, addEdgeLabels, addNodeAttribute, addNodeAttribute, addNodeAttribute, addNodeLabels, isUsingInternalGraph, removeEdgeAttribute, removeNodeAttribute, setDirectedEdges, setRandomSeed, setUseInternalGraph

    Methods inherited from class org.graphstream.stream.SourceBase

    addAttributeSink, addElementSink, addSink, attributeSinks, clearAttributeSinks, clearElementSinks, clearSinks, elementSinks, removeAttributeSink, removeElementSink, removeSink, sendAttributeChangedEvent, sendAttributeChangedEvent, sendEdgeAdded, sendEdgeAdded, sendEdgeAttributeAdded, sendEdgeAttributeAdded, sendEdgeAttributeChanged, sendEdgeAttributeChanged, sendEdgeAttributeRemoved, sendEdgeAttributeRemoved, sendEdgeRemoved, sendEdgeRemoved, sendGraphAttributeAdded, sendGraphAttributeAdded, sendGraphAttributeChanged, sendGraphAttributeChanged, sendGraphAttributeRemoved, sendGraphAttributeRemoved, sendGraphCleared, sendGraphCleared, sendNodeAdded, sendNodeAdded, sendNodeAttributeAdded, sendNodeAttributeAdded, sendNodeAttributeChanged, sendNodeAttributeChanged, sendNodeAttributeRemoved, sendNodeAttributeRemoved, sendNodeRemoved, sendNodeRemoved, sendStepBegins, sendStepBegins

    Methods inherited from class java.lang.Object

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

    Methods inherited from interface org.graphstream.stream.Source

    addAttributeSink, addElementSink, addSink, clearAttributeSinks, clearElementSinks, clearSinks, removeAttributeSink, removeElementSink, removeSink

  • Constructor Details

    • WattsStrogatzGenerator

      public WattsStrogatzGenerator​(int n, int k, double beta)
      New Watts-Strogatz generator.
      Parameters:
      n - The number of nodes to generate.
      k - The base degree of each node.
      beta - Probability to "rewire" an edge.

  • Method Details

    • begin

      public void begin()
      Description copied from interface: Generator
      Begin the graph generation. This usually is the place for initialization of the generator. After calling this method, call the Generator.nextEvents() method to add elements to the graph.

    • nextEvents

      public boolean nextEvents()
      Description copied from interface: Generator
      Perform the next step in generating the graph. While this method returns true, there are still more elements to add to the graph to generate it. Be careful that some generators never return false here, since they can generate graphs of arbitrary size. For such generators, simply stop calling this method when enough elements have been generated. A call to this method can produce an undetermined number of nodes and edges. Checking nodes count is advisable when generating the graph to avoid an unwanted big graph.
      Returns:
      true while there are elements to add to the graph.

    • end

      public void end()
      Description copied from class: BaseGenerator
      End the graph generation by finalizing it. Once the Generator.nextEvents() method returned false (or even if you stop before), this method must be called to finish the graph. In addition, BaseGenerator adds a "clear" operations that removes all the kept edges and nodes identifiers and the associated data.
      Specified by:
      end in interface Generator
      Overrides:
      end in class BaseGenerator