NAME

Graph::Easy - Render graphs as ASCII, HTML, SVG or Graphviz

SYNOPSIS

	use Graph::Easy;
	
	my $graph = Graph::Easy->new();

	$graph->add_edge ('Bonn', 'Berlin');

	print $graph->as_ascii( );

	# prints:

	# +------+     +--------+
	# | Bonn | --> | Berlin |
	# +------+     +--------+

	# slightly more verbose way:

	my $graph = Graph::Easy->new();

	my $bonn = Graph::Easy->add_node('Bonn');
	$bonn->set_attribute('border', 'solid 1px black')

	my $berlin = $graph->add_node('Berlin');

	$graph->add_edge ($bonn, $berlin);

	print $graph->as_ascii( );

	# adding edges with attributes:

        my $edge = Graph::Easy::Edge->new(
                label => 'train',
                style => 'dotted',
                color => 'red',
        );

	# now with the optional edge object
	$graph->add_edge ($bonn, $berlin, $edge);

	# raw HTML section
	print $graph->as_html( );

	# complete HTML page (with CSS)
	print $graph->as_html_file( );

	# creating a graph from a textual description	
	use Graph::Easy::Parser;
	my $parser = Graph::Easy::Parser->new();

	my $graph = $parser->from_text(
		"[ Bonn ] => [ Berlin ] \n".
		"[ Bonn ] => [ Rostock ]"
	);

	print $graph->as_ascii( );

	# Outputs something like:

	# +------+       +---------+
	# | Bonn |   --> | Rostock |
	# +------+       +---------+
	#   |
	#   |
	#   v
	# +--------+
	# | Berlin |
	# +--------+

	# Other possibilities:

	# SVG (possible after you installed Graph::Easy::As_svg):
	print $graph->as_svg( );

	# Graphviz:
	my $graphviz = $graph->as_graphviz();
	`dot -Tpng -o graph.png $graphviz`;

DESCRIPTION

Graph::Easy lets you generate graphs consisting of various shaped boxes connected with arrows.

It works on a grid (manhattan layout), and thus the output is most usefull for flow charts, network diagrams, or hirarchy trees.

Input

Apart from driving the module with Perl code, you can also use Graph::Easy::Parser to parse graph descriptions like:

[ Bonn ]      --> [ Berlin ]
[ Frankfurt ] <=> [ Dresden ]
[ Bonn ]      --> [ Frankfurt ]

See EXAMPLES for how this might be rendered.

Creating graphs

First, create a graph object:

my $graph = Graph::Easy->new();

Then add a node to it:

my $node = $graph->add_node('Koblenz');

Don't worry, adding the node again will do nothing:

$node = $graph->add_node('Koblenz');

You can get back a node by its name with node():

$node = $graph->node('Koblenz');

You can either add another node:

my $second = $graph->node('Frankfurt');

Or add an edge straight-away:

my ($first,$second,$edge) = $graph->add_edge('Mainz','Ulm');

Adding the edge the second time creates another edge from 'Mainz' to 'Ulm':

my $other_edge;
 ($first,$second,$other_edge) = $graph->add_edge('Mainz','Ulm');

You can even add a self-loop:

$graph->add_edge('Bremen','Bremen');

Output

The output can be done in various styles:

ASCII ART: Uses things like +, - < and | to render the boxes.
HTML: HTML tables with CSS making everything "pretty".
SVG: Creates a Scalable Vector Graphics output.
Graphviz: Creates graphviz code that can be feed to 'dot', 'neato' or similiar programs.

EXAMPLES

The following examples are given in the simple text format that is understood by Graph::Easy::Parser.

You can also see many more examples at:

http://bloodgate.com/perl/graph/

One node

The most simple graph (apart from the empty one :) is a graph consisting of only one node:

[ Dresden ]

Two nodes

A simple graph consisting of two nodes, linked together by a directed edge:

[ Bonn ] -> [ Berlin ]

Three nodes

A graph consisting of three nodes, and both are linked from the first:

[ Bonn ] -> [ Berlin ]
[ Bonn ] -> [ Hamburg ]

Three nodes in a chain

A graph consisting of three nodes, showing that you can chain connections together:

[ Bonn ] -> [ Berlin ] -> [ Hamburg ]

Two not connected graphs

A graph consisting of two seperate parts, both of them not connected to each other:

[ Bonn ] -> [ Berlin ]
[ Freiburg ] -> [ Hamburg ]

Three nodes, interlinked

A graph consisting of three nodes, and two of the are connected from the first node:

[ Bonn ] -> [ Berlin ]
[ Berlin ] -> [ Hamburg ]
[ Bonn ] -> [ Hamburg ]

Different edge styles

A graph consisting of a couple of nodes, linked with the different possible edge styles.

[ Bonn ] <-> [ Berlin ]		# bidirectional
[ Berlin ] ==> [ Rostock ]	# double
[ Hamburg ] ..> [ Altona ]	# dotted
[ Dresden ] - > [ Bautzen ]	# dashed
[ Leipzig ] ~~> [ Kirchhain ]	# wave
[ Hof ] .-> [ Chemnitz ]	# dot-dash
[ Magdeburg ] <=> [ Ulm ]	# bidrectional, double etc
[ Magdeburg ] -- [ Ulm ]	# arrow-less edge

More examples at: http://bloodgate.com/perl/graph/

METHODS

Graph::Easy supports the following methods:

new()

use Graph::Easy;

my $graph = Graph::Easy->new( );

Creates a new, empty Graph::Easy object.

Takes optinal a hash reference with a list of options. The following are valid options:

debug			if true, enables debug output

error()

my $error = $graph->error();

Returns the last error or '' for none. Optionally, takes an error message to be set.

$graph->error( 'Expected Foo, but found Bar.' );

add_edge()

my ($first, $second, $edge) = $graph->add_edge( 'node 1', 'node 2');
my $edge = $graph->add_edge( $x, $y, $edge);
$graph->add_edge( $x, $y);

Add an edge between nodes X and Y. The optional edge object defines the style of the edge, if not present, a default object will be used.

When called in scalar context, will return $edge. In array/list context it will return the two nodes and the edge object.

$x and $y should be either plain scalars with the names of the nodes, or objects of Graph::Easy::Node, while the optional $edge should be Graph::Easy::Edge.

Note: Graph::Easy graphs are multi-edged, and adding the same edge twice will result in two edges going from $x to $y!

You can use edge() to check whether an edge from X to Y already exists in the graph.

add_node()

my $node = $graph->add_node( 'Node 1' );
$graph->add_node( $x );

Add a single node X to the graph. $x should be either a Graph::Easy::Node object, or a unique name for the node. Will do nothing if the node already exists in the graph.

It returns an Graph::Easy::Node object.

add_cluster()

$cluster = $graph->add_cluster( 'cluster name' );

Create a cluster with the given name, and add it to the graph. The cluster is initially empty, you can add nodes to it with:

$cluster->add_node( $node );

and set it's center node with:

$cluster->center( $node );

Please see Graph::Easy::Cluster for more information.

get_attribute()

my $value = $graph->get_attribute( $class, $name );

Return the value of attribute $name from class $class.

Example:

my $color = $graph->attribute( 'node', 'color' );

attribute()

my $value = $graph->attribute( $class, $name );

attribute is an alias for get_attribute.

set_attribute()

$graph->set_attribute( $class, $name, $val );

Sets a given attribute named $name to the new value $val in the class specified in $class.

Example:

$graph->set_attribute( 'graph', 'gid', '123' );

The class can be one of graph, edge, node or group. The last three can also have subclasses like in node.subclassname.

set_attributes()

$graph->set_attributes( $class, $att );

Given a class name in $class and a hash of mappings between attribute names and values in $att, will set all these attributes.

The class can be one of graph, edge, node or group. The last three can also have subclasses like in node.subclassname.

Example:

$graph->set_attributes( 'node', { color => 'red', background => 'none' } );

timeout()

print $graph->timeout(), " seconds timeout for layouts.\n";
$graph->timeout(12);

Get/set the timeut for layouts in seconds. If the layout process did not finish after that time, it will be stopped and a warning will be printed.

layout()

$graph->layout();

Creates the internal structures to layout the graph. Usually you need not to call this method, because it will be done automatically when you call any of the as_FOO methods below.

as_ascii()

print $graph->as_ascii();

Return the graph layout in ASCII art.

as_ascii_html()

print $graph->as_ascii_html();

Return the graph layout in ASCII art, suitable to be embedded into an HTML page. Basically wraps the output from as_ascii() into <pre> </pre>.

as_html()

print $graph->as_html();

Return the graph layout as HTML section. See css() to get the CSS section to go with that HTML code. If you want a complete HTML page then use as_html_file().

as_html_file()

print $graph->as_html_file();

Return the graph layout as HTML complete with headers, CSS section and footer. Can be viewed in the browser of your choice.

html_page_header()

my $header = $graph->html_page_header();

Return the header of an HTML page. Used together with html_page_footer by as_html_page to construct a complete HTML page.

html_page_footer()

my $footer = $graph->html_page_footer();

Return the footer of an HTML page. Used together with html_page_header by as_html_page to construct a complete HTML page.

css()

my $css = $graph->css();

Return CSS code for that graph. See as_html().

as_txt()

print $graph->as_txt();

Return the graph as a textual representation, that can be parsed with Graph::Easy::Parser back to a graph.

This does not call layout() since the actual text representation is more a dump of the graph, than a certain layout.

nodes()

my $nodes = $graph->nodes();

In scalar context, returns the number of nodes/vertices the graph has. In list context returns a list of all the node objects (as reference).

sorted_nodes()

my $nodes =
 $graph->sorted_nodes( );		# default sort on 'id'
my $nodes = 
 $graph->sorted_nodes( 'name' );	# sort on 'name'
my $nodes = 
 $graph->sorted_nodes( 'layer', 'id' );	# sort on 'layer', then on 'id'

In scalar context, returns the number of nodes/vertices the graph has. In list context returns a list of all the node objects (as reference), sorted by their attribute(s) given as arguments. The default is 'id', e.g. their internal ID number, which amounts more or less to the order they have been inserted.

node()

my $node = $graph->node('node name');

Return node by unique name (case sensitive). Returns undef if the node does not exist in the graph.

edge()

my $edge = $graph->edge( $x, $y );

Returns the edge object between nodes $x and $y. Both $x and $y can be either scalars with names or Graph::Easy::Node objects.

Returns undef if the edge does not yet exist.

If there exist more than one edge from $x to $y, then only the first edge object will be returned.

cluster()

my $cluster = $graph->cluster( 'name' );

Returns a Graph::Easy::Cluster object or undef if it doesn't exist in this graph.

id()

my $graph_id = $graph->id();
$graph->id('123');

Returns the id of the graph. You can also set a new ID with this routine. The default is ''.

The graph's ID is used to generate unique CSS classes for each graph, in the case you want to have more than one graph in an HTML page.

seed()

my $seed = $graph->seed();
$graph->seed(2);

Get/set the random seed for the graph object. See randomize() for a method to set a random seed.

The seed is used to create random numbers for the layouter. For the same graph, the same seed will always lead to the same layout.

randomize()

$graph->randomize();

Set a random seed for the graph object. See seed().

debug()

my $debug = $graph->debug();	# get
$graph->debug(1);		# enable
$graph->debug(0);		# disable

Enable, disable or read out the debug status. When the debug status is true, additional debug messages will be printed on STDERR.

score()

my $score = $graph->score();

Returns the score of the graph, or undef if layout() has not yet been called.

Higher scores are better, although you cannot compare scores for different graphs. The score should only be used to compare different layouts of the same graph against each other:

my $max = undef;

$graph->randomize();
my $seed = $graph->seed(); 

$graph->layout();
$max = $graph->score(); 

for (1..10)
  {
  $graph->randomize();			# select random seed
  $graph->layout();			# layout with that seed
  if ($graph->score() > $max)
    {
    $max = $graph->score();		# store the new max store
    $seed = $graph->seed();		# and it's seed
    }
  }

# redo the best layout
if ($seed ne $graph->seed())
  {
  $graph->seed($seed);
  $graph->layout();
  }
# output graph:
print $graph->as_ascii();		# or as_html() etc

EXPORT

Exports nothing.

LIMITATIONS

This module is a proof-of-concept and has currently some limitations. Hopefully further development will lift these.

Scoring

Scoring is not yet implemented, each generated graph will be the same regardless of the random seed.

Syntax

See http://bloodgate.com/perl/graph/ for limits of the syntax. Mostly this are limitations in the parser, which cannot yet handle the following features:

nesting (graph-in-a-node)

node lists

Node lists only work on the left side of an expression. E.g. the first line works, the second and third do not:

[ Bonn ], [ Hof ] -> [ Berlin ]
[ Frankfurt ] -> [ Hamburg ], [ Dresden ]
[ Cottbus ], [ Kamenz ] -> [ Plauen ], [ Bamberg ]

scopes

Paths

Too bendy paths

The A* algorithm sometimes creates unnecessary bends in a path. A tweak which will prevent would be decreasing the value of an already open node, but this has not yet been implemented.

No joints

Currently it is not possible that an edge joins another edge like this:

+------+     +--------+     +-----------+
| Bonn | --> | Berlin | --> | Magdeburg |
+------+     +--------+     +-----------+
  |            |	      |
  |            |	      |
  |            |	      v
  |            v	    +---------+
  +-----------------------> | Potsdam |
             		    +---------+

No optimizations

Non-optimal layouts like this one might appear from time to time:

+------+     +--------+
| Bonn | --> | Berlin |
+------+     +--------+
               ^
               |
               |
+---------+    |
| Kassel  | ---+
+---------+

A second-stage optimizer that simplifies these layouts is not yet implemented.

In addition the general placement/processing strategy as well as the local strategy might be improved.

ASCII edge labels

Edges in ASCII miss their edge labels.

# [ Bonn ] - train -> [ Berlin ] will be rendered as:

+------+     +--------+
| Bonn | --> | Berlin |
+------+     +--------+

Node-Size

A node consisting of multiple cells will be rendered incorrectly on output.

Nodes with more than one cell are automatically generated when they are overly wide or high, or when they have more than four incoming/outgoing edges.

Grouping

The output of the graphs in ASCII does not yet include the group information.

Other formats

Formats other than ASCII and HTML are not yet complete in their implementation. If you notice any bugs or defiencies, please drop me a note!

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms of the GPL version 2. See the LICENSE file for information.

NAME CHANGE

The package was formerly known as Graph::Simple. The name was changed for two reasons:

In graph theory, a simple graph is a special type of graph. This software, however, supports more than simple graphs.
Creating graphs should be easy even when the graphs are quite complex.

AUTHOR

To install Graph::Easy, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Graph::Easy

CPAN shell

perl -MCPAN -e shell
install Graph::Easy

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

SYNOPSIS

DESCRIPTION

Input

Creating graphs

Output

EXAMPLES

One node

Two nodes

Three nodes

Three nodes in a chain

Two not connected graphs

Three nodes, interlinked

Different edge styles

METHODS

new()

error()

add_edge()

add_node()

add_cluster()

get_attribute()

attribute()

set_attribute()

set_attributes()

timeout()

layout()

as_ascii()

as_ascii_html()

as_html()

as_html_file()

html_page_header()

html_page_footer()

css()

as_txt()

nodes()

sorted_nodes()

node()

edge()

cluster()

id()

seed()

randomize()

debug()

score()

EXPORT

SEE ALSO

LIMITATIONS

Scoring

Syntax

Paths

Node-Size

Grouping

Other formats

LICENSE

NAME CHANGE

AUTHOR

Module Install Instructions