Package it.unimi.dsi.webgraph.examples

Class ErdosRenyiGraph

java.lang.Object

it.unimi.dsi.webgraph.ImmutableGraph

it.unimi.dsi.webgraph.ImmutableSequentialGraph

it.unimi.dsi.webgraph.examples.ErdosRenyiGraph

All Implemented Interfaces:

FlyweightPrototype<ImmutableGraph>

public class ErdosRenyiGraph
extends ImmutableSequentialGraph

An Erdős–Rényi random graph: the number of nodes is fixed, and there is a fixed probability that an arc is put between any two nodes (independently for every pair).

Note that an instance of this class is not random-access: you can, however, make a mutable copy of the returned graph and then take its immutable view.

Warning: From version 3.5.2, this classes uses BinomialDistribution instead of the previous COLT-based Binomial class. As a side-effect, the graphs generated with the same parameters will be different.

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.webgraph.ImmutableGraph

ImmutableGraph.LoadMethod

Field Summary

Fields inherited from class it.unimi.dsi.webgraph.ImmutableGraph

GRAPHCLASS_PROPERTY_KEY, NUMBER_OF_THREADS_PROPERTY, PROPERTIES_EXTENSION

Constructor Summary

Constructors

Constructor	Description
ErdosRenyiGraph(int n, double p)	Creates an Erdős–Rényi graph with given parameters and no loops.
ErdosRenyiGraph(int n, double p, boolean loops)	Creates an Erdős–Rényi graph with given parameters.
ErdosRenyiGraph(int n, double p, long seed, boolean loops)	Creates an Erdős–Rényi graph with given parameters and random seed.
ErdosRenyiGraph(int n, long m, boolean loops)	Creates an Erdős–Rényi graph with given parameters and random seed.
ErdosRenyiGraph(int n, long m, long seed, boolean loops)	Creates an Erdős–Rényi graph with given parameters and random seed.
ErdosRenyiGraph(String n, String p)	Creates an Erdős–Rényi graph with given parameters and no loops.
ErdosRenyiGraph(String n, String p, String loops)	Creates an Erdős–Rényi graph with given parameters.
ErdosRenyiGraph(String n, String p, String seed, String loops)	Creates an Erdős–Rényi graph with given parameters and random seed.

Method Summary

Modifier and Type	Method	Description
ErdosRenyiGraph	copy()	Throws an UnsupportedOperationException.
ImmutableGraph	generate()	Deprecated. An instance of this class is already an ImmutableSequentialGraph.
ImmutableSequentialGraph	generate(long seed)	Deprecated. An instance of this class is already an ImmutableSequentialGraph.
static void	main(String[] arg)
NodeIterator	nodeIterator()	Returns a node iterator for scanning the graph sequentially, starting from the first node.
int	numNodes()	Returns the number of nodes of this graph.

Methods inherited from class it.unimi.dsi.webgraph.ImmutableSequentialGraph

nodeIterator, outdegree, randomAccess, successorArray

Methods inherited from class it.unimi.dsi.webgraph.ImmutableGraph

basename, equals, hasCopiableIterators, hashCode, load, load, load, loadMapped, loadMapped, loadOffline, loadOffline, loadOnce, loadSequential, loadSequential, numArcs, outdegrees, splitNodeIterators, store, store, successors, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

ErdosRenyiGraph

public ErdosRenyiGraph(int n,
double p,
long seed,
boolean loops)

Creates an Erdős–Rényi graph with given parameters and random seed.

Parameters:

n - the number of nodes.

p - the probability of generating an arc.

seed - a seed for pseudorandom number generation.

loops - whether loops are allowed or not.

ErdosRenyiGraph

public ErdosRenyiGraph(int n,
double p,
boolean loops)

Creates an Erdős–Rényi graph with given parameters.

Parameters:

n - the number of nodes.

p - the probability of generating an arc.

loops - whether loops are allowed or not.

ErdosRenyiGraph

public ErdosRenyiGraph(int n,
double p)

Creates an Erdős–Rényi graph with given parameters and no loops.

Parameters:

n - the number of nodes.

p - the probability of generating an arc.

ErdosRenyiGraph

public ErdosRenyiGraph(String n,
String p,
String seed,
String loops)

Creates an Erdős–Rényi graph with given parameters and random seed.

This constructor can be used with an ObjectParser.

Parameters:

n - the number of nodes.

p - the probability of generating an arc.

seed - a seed for pseudorandom number generation.

loops - whether loops are allowed or not.

ErdosRenyiGraph

public ErdosRenyiGraph(String n,
String p)

Creates an Erdős–Rényi graph with given parameters and no loops.

This constructor can be used with an ObjectParser.

Parameters:

n - the number of nodes.

p - the probability of generating an arc.

ErdosRenyiGraph

public ErdosRenyiGraph(String n,
String p,
String loops)

Creates an Erdős–Rényi graph with given parameters.

This constructor can be used with an ObjectParser.

Parameters:

n - the number of nodes.

p - the probability of generating an arc.

loops - whether loops are allowed or not.

ErdosRenyiGraph

public ErdosRenyiGraph(int n,
long m,
long seed,
boolean loops)

Creates an Erdős–Rényi graph with given parameters and random seed.

Parameters:

n - the number of nodes.

m - the expected number of arcs.

seed - a seed for pseudorandom number generation.

loops - whether loops are allowed or not.

ErdosRenyiGraph

public ErdosRenyiGraph(int n,
long m,
boolean loops)

Creates an Erdős–Rényi graph with given parameters and random seed.

Parameters:

n - the number of nodes.

m - the expected number of arcs.

loops - whether loops are allowed or not.

Method Details

numNodes

public int numNodes()

Description copied from class: ImmutableGraph

Returns the number of nodes of this graph.

Albeit this method is not optional, it is allowed that this method throws an UnsupportedOperationException if this graph has never been entirely traversed using a node iterator. This apparently bizarre behaviour is necessary to support implementations as ArcListASCIIGraph, which do not know the actual number of nodes until a traversal has been completed.

Specified by:

numNodes in class ImmutableGraph

Returns:

the number of nodes.

copy

public ErdosRenyiGraph copy()

Description copied from class: ImmutableSequentialGraph

Throws an UnsupportedOperationException.

Specified by:

copy in interface FlyweightPrototype<ImmutableGraph>

Overrides:

copy in class ImmutableSequentialGraph

Returns:

a flyweight copy of this immutable graph.

See Also:

FlyweightPrototype

nodeIterator

public NodeIterator nodeIterator()

Description copied from class: ImmutableGraph

Returns a node iterator for scanning the graph sequentially, starting from the first node.

Overrides:

nodeIterator in class ImmutableGraph

Returns:

a NodeIterator for accessing nodes and successors sequentially.

generate

@Deprecated
public ImmutableSequentialGraph generate(long seed)

Deprecated.

An instance of this class is already an ImmutableSequentialGraph.

Generates an Erdős–Rényi graph with the specified seed.

This method exists only for backward compatibility.

Parameters:

seed - the seed for random generation.

Returns:

the generated graph.

generate

@Deprecated
public ImmutableGraph generate()

Deprecated.

An instance of this class is already an ImmutableSequentialGraph.

Generates an Erdős–Rényi graph.

This method exists only for backward compatibility.

Returns:

the generated graph.

main

public static void main(String[] arg)
                 throws IOException,
JSAPException

Throws:

IOException

JSAPException