Package it.unimi.dsi.webgraph

Class ScatteredArcsASCIIGraph

java.lang.Object

it.unimi.dsi.webgraph.ImmutableGraph

it.unimi.dsi.webgraph.ImmutableSequentialGraph

it.unimi.dsi.webgraph.ScatteredArcsASCIIGraph

All Implemented Interfaces:

FlyweightPrototype<ImmutableGraph>

public class ScatteredArcsASCIIGraph
extends ImmutableSequentialGraph

An ImmutableGraph that corresponds to a graph stored as a scattered list of arcs.

A scattered list of arcs describes a graph in a fairly loose way. Each line contains an arc specified as two node identifiers separated by whitespace (but we suggest exactly one TAB character). Sources and targets can be in any order.

In the standard description, node identifiers can be in the range [-2⁶³..2⁶³): they will be remapped in a compact identifier space by assigning to each newly seen identifier a new node number. The list of identifiers in order of appearance is available in ids. Lines can be empty, or comments starting with #. Characters following the target will be discarded with a warning.

Warning: Lines not conforming the above specification will cause an error to be logged, but will be otherwise ignored.

Alternatively, you can provide an Object2LongFunction<String> with default return value -1 that will be used to map identifiers to node numbers, along with a Charset to parse lines and the number of nodes of the graph (which must be a strict upper bound for the largest value returned by the function). Note that in principle an Object2IntFunction would be sufficient, but we want to make easier using functions from Sux4J such as GOV3Function.

Additionally, the resulting graph can be symmetrized, and its loops be removed, using suitable constructor options.

This class has no load method, and its main method converts a scattered-arcs representation directly into a BVGraph.

Using ScatteredArcsASCIIGraph to convert your data

A simple (albeit rather inefficient) way to import data into WebGraph is using ASCII graphs specified by scattered arcs. Suppose you create the following file, named example.arcs:

  # My graph
  -1 15
  15 2
  2 -1 This will cause a warning to be logged
  OOPS! (This will cause an error to be logged)
  -1 2
 

Then, the command

  java it.unimi.dsi.webgraph.ScatteredArcsASCIIGraph example <example.arcs
 

will produce a compressed graph in BVGraph format with basename example. The file example.ids will contain the list of longs -1, 15, 2. The node with identifer -1 will be the node 0 in the output graph, the node with identifier 15 will be node 1, and the node with identifier 2 will be node 2. The graph example will thus have three nodes and four arcs (viz., <0,1>, <0,2>, <1,2> and <2,0>).

Memory requirements

To convert node identifiers to node numbers, instances of this class use a custom map that in the worst case will require 19.5×2^{⌈log(4n/3)⌉} ≤ 52n bytes, where n is the number of distinct identifiers. Storing batches of arcs in memory requires 8 bytes per arc.

Nested Class Summary

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

ImmutableGraph.LoadMethod

Field Summary

Fields

Modifier and Type	Field	Description
static int	DEFAULT_BATCH_SIZE	The default batch size.
long[]	ids	The list of identifiers in order of appearance.

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

GRAPHCLASS_PROPERTY_KEY, NUMBER_OF_THREADS_PROPERTY, PROPERTIES_EXTENSION

Constructor Summary

Constructors

Constructor	Description
ScatteredArcsASCIIGraph(InputStream is)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, boolean symmetrize)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, boolean symmetrize, boolean noLoops)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, boolean symmetrize, boolean noLoops, int batchSize)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, boolean symmetrize, boolean noLoops, int batchSize, File tempDir)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, boolean symmetrize, boolean noLoops, int batchSize, File tempDir, ProgressLogger pl)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, Object2LongFunction<? extends CharSequence> function, Charset charset, int n)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, Object2LongFunction<? extends CharSequence> function, Charset charset, int n, boolean symmetrize)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, Object2LongFunction<? extends CharSequence> function, Charset charset, int n, boolean symmetrize, boolean noLoops)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, Object2LongFunction<? extends CharSequence> function, Charset charset, int n, boolean symmetrize, boolean noLoops, int batchSize)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, Object2LongFunction<? extends CharSequence> function, Charset charset, int n, boolean symmetrize, boolean noLoops, int batchSize, File tempDir)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(InputStream is, Object2LongFunction<? extends CharSequence> function, Charset charset, int n, boolean symmetrize, boolean noLoops, int batchSize, File tempDir, ProgressLogger pl)	Creates a scattered-arcs ASCII graph.
ScatteredArcsASCIIGraph(Iterator<long[]> arcs, boolean symmetrize, boolean noLoops, int batchSize, File tempDir, ProgressLogger pl)	Creates a scattered-arcs ASCII graph.

Method Summary

Modifier and Type	Method	Description
ScatteredArcsASCIIGraph	copy()	Throws an UnsupportedOperationException.
boolean	hasCopiableIterators()	Whether the node iterators returned by this graph support NodeIterator.copy(int).
static void	main(String[] args)
NodeIterator	nodeIterator(int from)	Returns a node iterator for scanning the graph sequentially, starting from the given node.
long	numArcs()	Returns the number of arcs of this graph (optional operation).
int	numNodes()	Returns the number of nodes of this graph.

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

outdegree, randomAccess, successorArray

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

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

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_BATCH_SIZE

public static final int DEFAULT_BATCH_SIZE

The default batch size.

See Also:

Constant Field Values

ids

public long[] ids

The list of identifiers in order of appearance.

Constructor Details

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a standard scattered list of arcs.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
boolean symmetrize)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a standard scattered list of arcs.

symmetrize - the new graph will be forced to be symmetric.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
boolean symmetrize,
boolean noLoops)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a standard scattered list of arcs.

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
boolean symmetrize,
boolean noLoops,
int batchSize)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a standard scattered list of arcs.

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
boolean symmetrize,
boolean noLoops,
int batchSize,
File tempDir)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a standard scattered list of arcs.

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

tempDir - a temporary directory for the batches, or null for File.createTempFile(java.lang.String, java.lang.String)'s choice.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
boolean symmetrize,
boolean noLoops,
int batchSize,
File tempDir,
ProgressLogger pl)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a standard scattered list of arcs.

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

tempDir - a temporary directory for the batches, or null for File.createTempFile(java.lang.String, java.lang.String)'s choice.

pl - a progress logger, or null.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
Object2LongFunction<? extends CharSequence> function,
Charset charset,
int n)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a scattered list of arcs.

function - an explicitly provided function from string representing nodes to node numbers, or null for the standard behaviour.

charset - a character set that will be used to read the identifiers passed to function, or null for ISO-8859-1 (used only if function is not null).

n - the number of nodes of the graph (used only if function is not null).

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
Object2LongFunction<? extends CharSequence> function,
Charset charset,
int n,
boolean symmetrize)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a scattered list of arcs.

function - an explicitly provided function from string representing nodes to node numbers, or null for the standard behaviour.

charset - a character set that will be used to read the identifiers passed to function, or null for ISO-8859-1 (used only if function is not null).

n - the number of nodes of the graph (used only if function is not null).

symmetrize - the new graph will be forced to be symmetric.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
Object2LongFunction<? extends CharSequence> function,
Charset charset,
int n,
boolean symmetrize,
boolean noLoops)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a scattered list of arcs.

function - an explicitly provided function from string representing nodes to node numbers, or null for the standard behaviour.

charset - a character set that will be used to read the identifiers passed to function, or null for ISO-8859-1 (used only if function is not null).

n - the number of nodes of the graph (used only if function is not null).

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
Object2LongFunction<? extends CharSequence> function,
Charset charset,
int n,
boolean symmetrize,
boolean noLoops,
int batchSize)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a scattered list of arcs.

function - an explicitly provided function from string representing nodes to node numbers, or null for the standard behaviour.

charset - a character set that will be used to read the identifiers passed to function, or null for ISO-8859-1 (used only if function is not null).

n - the number of nodes of the graph (used only if function is not null).

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
Object2LongFunction<? extends CharSequence> function,
Charset charset,
int n,
boolean symmetrize,
boolean noLoops,
int batchSize,
File tempDir)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a scattered list of arcs.

function - an explicitly provided function from string representing nodes to node numbers, or null for the standard behaviour.

charset - a character set that will be used to read the identifiers passed to function, or null for ISO-8859-1 (used only if function is not null).

n - the number of nodes of the graph (used only if function is not null).

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

tempDir - a temporary directory for the batches, or null for File.createTempFile(java.lang.String, java.lang.String)'s choice.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(InputStream is,
Object2LongFunction<? extends CharSequence> function,
Charset charset,
int n,
boolean symmetrize,
boolean noLoops,
int batchSize,
File tempDir,
ProgressLogger pl)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

is - an input stream containing a scattered list of arcs.

function - an explicitly provided function from string representing nodes to node numbers, or null for the standard behaviour.

charset - a character set that will be used to read the identifiers passed to function, or null for ISO-8859-1 (used only if function is not null).

n - the number of nodes of the graph (used only if function is not null).

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

tempDir - a temporary directory for the batches, or null for File.createTempFile(java.lang.String, java.lang.String)'s choice.

pl - a progress logger, or null.

Throws:

IOException

ScatteredArcsASCIIGraph

public ScatteredArcsASCIIGraph(Iterator<long[]> arcs,
boolean symmetrize,
boolean noLoops,
int batchSize,
File tempDir,
ProgressLogger pl)
                        throws IOException

Creates a scattered-arcs ASCII graph.

Parameters:

arcs - an iterator returning the arcs as two-element arrays.

symmetrize - the new graph will be forced to be symmetric.

noLoops - the new graph will have no loops.

batchSize - the number of integers in a batch; two arrays of integers of this size will be allocated by this method.

tempDir - a temporary directory for the batches, or null for File.createTempFile(java.lang.String, java.lang.String)'s choice.

pl - a progress logger, or null.

Throws:

IOException

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.

numArcs

public long numArcs()

Description copied from class: ImmutableGraph

Returns the number of arcs of this graph (optional operation).

Overrides:

numArcs in class ImmutableGraph

Returns:

the number of arcs.

nodeIterator

public NodeIterator nodeIterator(int from)

Description copied from class: ImmutableGraph

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

Overrides:

nodeIterator in class ImmutableSequentialGraph

Parameters:

from - the node from which the iterator will iterate.

Returns:

a NodeIterator for accessing nodes and successors sequentially.

hasCopiableIterators

public boolean hasCopiableIterators()

Description copied from class: ImmutableGraph

Whether the node iterators returned by this graph support NodeIterator.copy(int).

Overrides:

hasCopiableIterators in class ImmutableGraph

Returns:

true if this graph provides copiable iterators.

copy

public ScatteredArcsASCIIGraph 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

main

public static void main(String[] args)
                 throws IllegalArgumentException,
SecurityException,
IOException,
JSAPException,
ClassNotFoundException

Throws:

IllegalArgumentException

SecurityException

IOException

JSAPException

ClassNotFoundException