Package it.unimi.dsi.big.webgraph.examples

Class IntegerListImmutableGraph

java.lang.Object

it.unimi.dsi.big.webgraph.ImmutableGraph

it.unimi.dsi.big.webgraph.ImmutableSequentialGraph

it.unimi.dsi.big.webgraph.examples.IntegerListImmutableGraph

All Implemented Interfaces:

it.unimi.dsi.lang.FlyweightPrototype<ImmutableGraph>

public class IntegerListImmutableGraph
extends ImmutableSequentialGraph

Exposes a graph in a simple binary format as an (offline-only) ImmutableGraph.

This class is a simple example that should help in understanding how to interface WebGraph with external data. We have a graph contained in a file and represented by a list of binary 32-bit integers as follows: first we have the number of nodes, then the number of successors of node 0, then the list in increasing order of successors of node 0, then the number of successors of node 1, then the list in increasing order of successors of node 1, and so on.

If we want to transform this graph into, say, a BVGraph, we must create a class that exposes the file as an ImmutableGraph and than save it using BVGraph.store(ImmutableGraph,CharSequence) or by calling the main method of BVGraph. A complete implementation is not necessary, as BVGraph uses just nodeIterator(). Since we are just interesting in importing data, we do not implement efficient random access methods, and the only loading method we implement is loadOffline(CharSequence).

Nested Class Summary

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

ImmutableGraph.LoadMethod

Field Summary

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

GRAPHCLASS_PROPERTY_KEY, NUMBER_OF_THREADS_PROPERTY, PROPERTIES_EXTENSION

Method Summary

Modifier and Type	Method	Description
static ImmutableGraph	load(java.lang.CharSequence basename)
static ImmutableGraph	load(java.lang.CharSequence basename, it.unimi.dsi.logging.ProgressLogger pl)
static ImmutableGraph	loadOffline(java.lang.CharSequence basename)
static ImmutableGraph	loadOffline(java.lang.CharSequence basename, it.unimi.dsi.logging.ProgressLogger pl)
static ImmutableGraph	loadSequential(java.lang.CharSequence basename)	Deprecated.
static ImmutableGraph	loadSequential(java.lang.CharSequence basename, it.unimi.dsi.logging.ProgressLogger pl)	Deprecated.
NodeIterator	nodeIterator()	Returns a node iterator for scanning the graph sequentially, starting from the first node.
long	numNodes()	Returns the number of nodes of this graph.

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

copy, nodeIterator, outdegree, randomAccess, successorBigArray

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

basename, equals, hasCopiableIterators, hashCode, intNumNodes, load, loadMapped, loadMapped, loadOnce, numArcs, outdegrees, splitNodeIterators, store, store, successors, toString, wrap, wrap

Methods inherited from class java.lang.Object

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

Method Detail

numNodes

public long 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.

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.

load

public static ImmutableGraph load(java.lang.CharSequence basename,
                                  it.unimi.dsi.logging.ProgressLogger pl)

load

public static ImmutableGraph load(java.lang.CharSequence basename)

loadSequential

@Deprecated
public static ImmutableGraph loadSequential(java.lang.CharSequence basename,
                                            it.unimi.dsi.logging.ProgressLogger pl)

Deprecated.

loadSequential

@Deprecated
public static ImmutableGraph loadSequential(java.lang.CharSequence basename)

Deprecated.

loadOffline

public static ImmutableGraph loadOffline(java.lang.CharSequence basename,
                                         it.unimi.dsi.logging.ProgressLogger pl)
                                  throws java.io.IOException

Throws:

java.io.IOException

loadOffline

public static ImmutableGraph loadOffline(java.lang.CharSequence basename)
                                  throws java.io.IOException

Throws:

java.io.IOException