1Graph::Easy(3)        User Contributed Perl Documentation       Graph::Easy(3)
2
3
4

NAME

6       Graph::Easy - Convert or render graphs (as ASCII, HTML, SVG or via
7       Graphviz)
8

SYNOPSIS

10               use Graph::Easy;
11
12               my $graph = Graph::Easy->new();
13
14               # make a fresh copy of the graph
15               my $new_graph = $graph->copy();
16
17               $graph->add_edge ('Bonn', 'Berlin');
18
19               # will not add it, since it already exists
20               $graph->add_edge_once ('Bonn', 'Berlin');
21
22               print $graph->as_ascii( );              # prints:
23
24               # +------+     +--------+
25               # | Bonn | --> | Berlin |
26               # +------+     +--------+
27
28               #####################################################
29               # alternatively, let Graph::Easy parse some text:
30
31               my $graph = Graph::Easy->new( '[Bonn] -> [Berlin]' );
32
33               #####################################################
34               # slightly more verbose way:
35
36               my $graph = Graph::Easy->new();
37
38               my $bonn = $graph->add_node('Bonn');
39               $bonn->set_attribute('border', 'solid 1px black');
40
41               my $berlin = $graph->add_node('Berlin');
42
43               $graph->add_edge ($bonn, $berlin);
44
45               print $graph->as_ascii( );
46
47               # You can use plain scalars as node names and for the edge label:
48               $graph->add_edge ('Berlin', 'Frankfurt', 'via train');
49
50               # adding edges with attributes:
51
52               my $edge = Graph::Easy::Edge->new();
53               $edge->set_attributes( {
54                       label => 'train',
55                       style => 'dotted',
56                       color => 'red',
57               } );
58
59               # now with the optional edge object
60               $graph->add_edge ($bonn, $berlin, $edge);
61
62               # raw HTML section
63               print $graph->as_html( );
64
65               # complete HTML page (with CSS)
66               print $graph->as_html_file( );
67
68               # Other possibilities:
69
70               # SVG (possible after you installed Graph::Easy::As_svg):
71               print $graph->as_svg( );
72
73               # Graphviz:
74               my $graphviz = $graph->as_graphviz();
75               open $DOT, '|dot -Tpng -o graph.png' or die ("Cannot open pipe to dot: $!");
76               print $DOT $graphviz;
77               close $DOT;
78
79               # Please see also the command line utility 'graph-easy'
80

DESCRIPTION

82       "Graph::Easy" lets you generate graphs consisting of various shaped
83       nodes connected by edges (with optional labels).
84
85       It can read and write graphs in a variety of formats, as well as render
86       them via its own grid-based layouter.
87
88       Since the layouter works on a grid (manhattan layout), the output is
89       most useful for flow charts, network diagrams, or hierarchy trees.
90
91   Input
92       Apart from driving the module with Perl code, you can also use
93       "Graph::Easy::Parser" to parse graph descriptions like:
94
95               [ Bonn ]      --> [ Berlin ]
96               [ Frankfurt ] <=> [ Dresden ]
97               [ Bonn ]      --  [ Frankfurt ]
98
99       See the "EXAMPLES" section below for how this might be rendered.
100
101   Creating graphs
102       First, create a graph object:
103
104               my $graph = Graph::Easy->new();
105
106       Then add a node to it:
107
108               my $node = $graph->add_node('Koblenz');
109
110       Don't worry, adding the node again will do nothing:
111
112               $node = $graph->add_node('Koblenz');
113
114       You can get back a node by its name with "node()":
115
116               $node = $graph->node('Koblenz');
117
118       You can either add another node:
119
120               my $second = $graph->node('Frankfurt');
121
122       Or add an edge straight-away:
123
124               my ($first,$second,$edge) = $graph->add_edge('Mainz','Ulm');
125
126       Adding the edge the second time creates another edge from 'Mainz' to
127       'Ulm':
128
129               my $other_edge;
130                ($first,$second,$other_edge) = $graph->add_edge('Mainz','Ulm');
131
132       This can be avoided by using "add_edge_once()":
133
134               my $edge = $graph->add_edge_once('Mainz','Ulm');
135               if (defined $edge)
136                 {
137                 # the first time the edge was added, do something with it
138                 $edge->set_attribute('color','blue');
139                 }
140
141       You can set attributes on nodes and edges:
142
143               $node->attribute('fill', 'yellow');
144               $edge->attribute('label', 'train');
145
146       It is possible to add an edge with a label:
147
148               $graph->add_edge('Cottbus', 'Berlin', 'my label');
149
150       You can also add self-loops:
151
152               $graph->add_edge('Bremen','Bremen');
153
154       Adding multiple nodes is easy:
155
156               my ($bonn,$rom) = Graph::Easy->add_nodes('Bonn','Rom');
157
158       You can also have subgraphs (these are called groups):
159
160               my ($group) = Graph::Easy->add_group('Cities');
161
162       Only nodes can be part of a group, edges are automatically considered
163       to be in the group if they lead from one node inside the group to
164       another node in the same group. There are multiple ways to add one or
165       more nodes into a group:
166
167               $group->add_member($bonn);
168               $group->add_node($rom);
169               $group->add_nodes($rom,$bonn);
170
171       For more options please see the online manual:
172       <http://bloodgate.com/perl/graph/manual/> .
173
174   Output
175       The output can be done in various styles:
176
177       ASCII ART
178         Uses things like "+", "-" "<" and "|" to render the boxes.
179
180       BOXART
181         Uses Unicode box art drawing elements to output the graph.
182
183       HTML
184         HTML tables with CSS making everything "pretty".
185
186       SVG
187         Creates a Scalable Vector Graphics output.
188
189       Graphviz
190         Creates graphviz code that can be feed to 'dot', 'neato' or similar
191         programs.
192
193       GraphML
194         Creates a textual description of the graph in the GraphML format.
195
196       GDL/VCG
197         Creates a textual description of the graph in the VCG or GDL (Graph
198         Description Language) format.
199

EXAMPLES

201       The following examples are given in the simple text format that is
202       understood by Graph::Easy::Parser.
203
204       You can also see many more examples at:
205
206       <http://bloodgate.com/perl/graph/>
207
208   One node
209       The most simple graph (apart from the empty one :) is a graph
210       consisting of only one node:
211
212               [ Dresden ]
213
214   Two nodes
215       A simple graph consisting of two nodes, linked together by a directed
216       edge:
217
218               [ Bonn ] -> [ Berlin ]
219
220   Three nodes
221       A graph consisting of three nodes, and both are linked from the first:
222
223               [ Bonn ] -> [ Berlin ]
224               [ Bonn ] -> [ Hamburg ]
225
226   Three nodes in a chain
227       A graph consisting of three nodes, showing that you can chain
228       connections together:
229
230               [ Bonn ] -> [ Berlin ] -> [ Hamburg ]
231
232   Two not connected graphs
233       A graph consisting of two separate parts, both of them not connected to
234       each other:
235
236               [ Bonn ] -> [ Berlin ]
237               [ Freiburg ] -> [ Hamburg ]
238
239   Three nodes, interlinked
240       A graph consisting of three nodes, and two of the are connected from
241       the first node:
242
243               [ Bonn ] -> [ Berlin ]
244               [ Berlin ] -> [ Hamburg ]
245               [ Bonn ] -> [ Hamburg ]
246
247   Different edge styles
248       A graph consisting of a couple of nodes, linked with the different
249       possible edge styles.
250
251               [ Bonn ] <-> [ Berlin ]         # bidirectional
252               [ Berlin ] ==> [ Rostock ]      # double
253               [ Hamburg ] ..> [ Altona ]      # dotted
254               [ Dresden ] - > [ Bautzen ]     # dashed
255               [ Leipzig ] ~~> [ Kirchhain ]   # wave
256               [ Hof ] .-> [ Chemnitz ]        # dot-dash
257               [ Magdeburg ] <=> [ Ulm ]       # bidrectional, double etc
258               [ Magdeburg ] -- [ Ulm ]        # arrow-less edge
259
260       More examples at: <http://bloodgate.com/perl/graph/>
261

ANIMATION SUPPORT

263       Note: Animations are not yet implemented!
264
265       It is possible to add animations to a graph. This is done by adding
266       steps via the pseudo-class "step":
267
268               step.0 {
269                 target: Bonn;         # find object with id=Bonn, or
270                                       # if this fails, the node named
271                                       # "Bonn".
272                 animate: fill:        # animate this attribute
273                 from: yellow;         # start value (0% of duration)
274                 via: red;             # at 50% of the duration
275                 to: yellow;           # and 100% of duration
276                 wait: 0;              # after triggering, wait so many seconds
277                 duration: 5;          # entire time to go from "from" to "to"
278                 trigger: onload;      # when to trigger this animation
279                 repeat: 2;            # how often to repeat ("2" means two times)
280                                       # also "infinite", then "next" will be ignored
281                 next: 1;              # which step to take after repeat is up
282               }
283               step.1 {
284                 from: white;          # set to white
285                 to: white;
286                 duration: 0.1;        # 100ms
287                 next: 0;              # go back to step.0
288               }
289
290       Here two steps are created, 0 and 1 and the animation will be going
291       like this:
292
293                                      0.1s
294                                    +-------------------------------+
295                                    v                               |
296               +--------+  0s   +--------+  5s   +--------+  5s   +--------+
297               | onload | ----> | step.0 | ----> | step.0 | ----> | step.1 |
298               +--------+       +--------+       +--------+       +--------+
299
300       You can generate a a graph with the animation flow via
301       "animation_as_graph()".
302
303   Output
304       Currently no output formats supports animations yet.
305

METHODS

307       "Graph::Easy" supports the following methods:
308
309   new()
310               use Graph::Easy;
311
312               my $graph = Graph::Easy->new( );
313
314       Creates a new, empty "Graph::Easy" object.
315
316       Takes optional a hash reference with a list of options. The following
317       are valid options:
318
319               debug                   if true, enables debug output
320               timeout                 timeout (in seconds) for the layouter
321               fatal_errors            wrong attributes are fatal errors, default: true
322               strict                  test attribute names for being valid, default: true
323               undirected              create an undirected graph, default: false
324
325   copy()
326           my $copy = $graph->copy( );
327
328       Create a copy of this graph and return it as a new Graph::Easy object.
329
330   error()
331               my $error = $graph->error();
332
333       Returns the last error or '' for none.  Optionally, takes an error
334       message to be set.
335
336               $graph->error( 'Expected Foo, but found Bar.' );
337
338       See warn() on how to catch error messages. See also non_fatal_errors()
339       on how to turn errors into warnings.
340
341   warn()
342               my $warning = $graph->warn();
343
344       Returns the last warning or '' for none.  Optionally, takes a warning
345       message to be output to STDERR:
346
347               $graph->warn( 'Expected Foo, but found Bar.' );
348
349       If you want to catch warnings from the layouter, enable catching of
350       warnings or errors:
351
352               $graph->catch_messages(1);
353
354               # Or individually:
355               # $graph->catch_warnings(1);
356               # $graph->catch_errors(1);
357
358               # something which warns or throws an error:
359               ...
360
361               if ($graph->error())
362                 {
363                 my @errors = $graph->errors();
364                 }
365               if ($graph->warning())
366                 {
367                 my @warnings = $graph->warnings();
368                 }
369
370       See Graph::Easy::Base for more details on error/warning message
371       capture.
372
373   add_edge()
374               my ($first, $second, $edge) = $graph->add_edge( 'node 1', 'node 2');
375
376   add_edge()
377               my ($first, $second, $edge) = $graph->add_edge( 'node 1', 'node 2');
378               my $edge = $graph->add_edge( $x, $y, $edge);
379               $graph->add_edge( $x, $y);
380
381       Add an edge between nodes X and Y. The optional edge object defines the
382       style of the edge, if not present, a default object will be used.
383
384       When called in scalar context, will return $edge. In array/list context
385       it will return the two nodes and the edge object.
386
387       $x and $y should be either plain scalars with the names of the nodes,
388       or objects of Graph::Easy::Node, while the optional $edge should be
389       Graph::Easy::Edge.
390
391       Note: "Graph::Easy" graphs are multi-edged, and adding the same edge
392       twice will result in two edges going from $x to $y! See
393       "add_edge_once()" on how to avoid that.
394
395       You can also use "edge()" to check whether an edge from X to Y already
396       exists in the graph.
397
398   add_edge_once()
399               my ($first, $second, $edge) = $graph->add_edge_once( 'node 1', 'node 2');
400               my $edge = $graph->add_edge_once( $x, $y, $edge);
401               $graph->add_edge_once( $x, $y);
402
403               if (defined $edge)
404                 {
405                 # got added once, so do something with it
406                 $edge->set_attribute('label','unique');
407                 }
408
409       Adds an edge between nodes X and Y, unless there exists already an edge
410       between these two nodes. See "add_edge()".
411
412       Returns undef when an edge between X and Y already exists.
413
414       When called in scalar context, will return $edge. In array/list context
415       it will return the two nodes and the edge object.
416
417   flip_edges()
418               my $graph = Graph::Easy->new();
419               $graph->add_edge('Bonn','Berlin');
420               $graph->add_edge('Berlin','Bonn');
421
422               print $graph->as_ascii();
423
424               #   +--------------+
425               #   v              |
426               # +--------+     +------+
427               # | Berlin | --> | Bonn |
428               # +--------+     +------+
429
430               $graph->flip_edges('Bonn', 'Berlin');
431
432               print $graph->as_ascii();
433
434               #   +--------------+
435               #   |              v
436               # +--------+     +------+
437               # | Berlin | --> | Bonn |
438               # +--------+     +------+
439
440       Turn around (transpose) all edges that are going from the first node to
441       the second node.
442
443   add_node()
444               my $node = $graph->add_node( 'Node 1' );
445               # or if you already have a Graph::Easy::Node object:
446               $graph->add_node( $x );
447
448       Add a single node X to the graph. $x should be either a
449       "Graph::Easy::Node" object, or a unique name for the node. Will do
450       nothing if the node already exists in the graph.
451
452       It returns an Graph::Easy::Node object.
453
454   add_anon_node()
455               my $anon_node = $graph->add_anon_node( );
456
457       Creates a single, anonymous node and adds it to the graph, returning
458       the "Graph::Easy::Node::Anon" object.
459
460       The created node is equal to one created via " [ ] " in the Graph::Easy
461       text description.
462
463   add_nodes()
464               my @nodes = $graph->add_nodes( 'Node 1', 'Node 2' );
465
466       Add all the given nodes to the graph. The arguments should be either a
467       "Graph::Easy::Node" object, or a unique name for the node. Will do
468       nothing if the node already exists in the graph.
469
470       It returns a list of Graph::Easy::Node objects.
471
472   rename_node()
473               $node = $graph->rename_node($node, $new_name);
474
475       Changes the name of a node. If the passed node is not part of this
476       graph or just a string, it will be added with the new name to this
477       graph.
478
479       If the node was part of another graph, it will be deleted there and
480       added to this graph with the new name, effectively moving the node from
481       the old to the new graph and renaming it at the same time.
482
483   del_node()
484               $graph->del_node('Node name');
485               $graph->del_node($node);
486
487       Delete the node with the given name from the graph.
488
489   del_edge()
490               $graph->del_edge($edge);
491
492       Delete the given edge object from the graph. You can use "edge()" to
493       find an edge from Node A to B:
494
495               $graph->del_edge( $graph->edge('A','B') );
496
497   merge_nodes()
498               $graph->merge_nodes( $first_node, $second_node );
499               $graph->merge_nodes( $first_node, $second_node, $joiner );
500
501       Merge two nodes. Will delete all connections between the two nodes,
502       then move over any connection to/from the second node to the first,
503       then delete the second node from the graph.
504
505       Any attributes on the second node will be lost.
506
507       If present, the optional $joiner argument will be used to join the
508       label of the second node to the label of the first node. If not
509       present, the label of the second node will be dropped along with all
510       the other attributes:
511
512               my $graph = Graph::Easy->new('[A]->[B]->[C]->[D]');
513
514               # this produces "[A]->[C]->[D]"
515               $graph->merge_nodes( 'A', 'B' );
516
517               # this produces "[A C]->[D]"
518               $graph->merge_nodes( 'A', 'C', ' ' );
519
520               # this produces "[A C \n D]", note single quotes on the third argument!
521               $graph->merge_nodes( 'A', 'C', ' \n ' );
522
523   get_attribute()
524               my $value = $graph->get_attribute( $class, $name );
525
526       Return the value of attribute $name from class $class.
527
528       Example:
529
530               my $color = $graph->attribute( 'node', 'color' );
531
532       You can also call all the various attribute related methods on members
533       of the graph directly, for instance:
534
535               $node->get_attribute('label');
536               $edge->get_attribute('color');
537               $group->get_attribute('fill');
538
539   attribute()
540               my $value = $graph->attribute( $class, $name );
541
542       Is an alias for get_attribute.
543
544   color_attribute()
545               # returns f.i. #ff0000
546               my $color = $graph->get_color_attribute( 'node', 'color' );
547
548       Just like get_attribute(), but only for colors, and returns them as
549       hex, using the current colorscheme.
550
551   get_color_attribute()
552       Is an alias for color_attribute().
553
554   get_attributes()
555               my $att = $object->get_attributes();
556
557       Return all effective attributes on this object (graph/node/group/edge)
558       as an anonymous hash ref. This respects inheritance and default values.
559
560       Note that this does not include custom attributes.
561
562       See also get_custom_attributes and raw_attributes().
563
564   get_custom_attributes()
565               my $att = $object->get_custom_attributes();
566
567       Return all the custom attributes on this object (graph/node/group/edge)
568       as an anonymous hash ref.
569
570   custom_attributes()
571               my $att = $object->custom_attributes();
572
573       "custom_attributes()" is an alias for get_custom_attributes.
574
575   raw_attributes()
576               my $att = $object->raw_attributes();
577
578       Return all set attributes on this object (graph, node, group or edge)
579       as an anonymous hash ref. Thus you get all the locally active
580       attributes for this object.
581
582       Inheritance is respected, e.g. attributes that have the value "inherit"
583       and are inheritable, will be inherited from the base class.
584
585       But default values for unset attributes are skipped. Here is an
586       example:
587
588               node { color: red; }
589
590               [ A ] { class: foo; color: inherit; }
591
592       This will return:
593
594               { class => foo, color => red }
595
596       As you can see, attributes like "background" etc. are not included,
597       while the color value was inherited properly.
598
599       See also get_attributes().
600
601   default_attribute()
602               my $def = $graph->default_attribute($class, 'fill');
603
604       Returns the default value for the given attribute in the class of the
605       object.
606
607       The default attribute is the value that will be used if the attribute
608       on the object itself, as well as the attribute on the class is unset.
609
610       To find out what attribute is on the class, use the three-arg form of
611       attribute on the graph:
612
613               my $g = Graph::Easy->new();
614               my $node = $g->add_node('Berlin');
615
616               print $node->attribute('fill'), "\n";           # print "white"
617               print $node->default_attribute('fill'), "\n";   # print "white"
618               print $g->attribute('node','fill'), "\n";       # print "white"
619
620               $g->set_attribute('node','fill','red');         # class is "red"
621               $node->set_attribute('fill','green');           # this object is "green"
622
623               print $node->attribute('fill'), "\n";           # print "green"
624               print $node->default_attribute('fill'), "\n";   # print "white"
625               print $g->attribute('node','fill'), "\n";       # print "red"
626
627       See also raw_attribute().
628
629   raw_attribute()
630               my $value = $object->raw_attribute( $name );
631
632       Return the value of attribute $name from the object it this method is
633       called on (graph, node, edge, group etc.). If the attribute is not set
634       on the object itself, returns undef.
635
636       This method respects inheritance, so an attribute value of 'inherit' on
637       an object will make the method return the inherited value:
638
639               my $g = Graph::Easy->new();
640               my $n = $g->add_node('A');
641
642               $g->set_attribute('color','red');
643
644               print $n->raw_attribute('color');               # undef
645               $n->set_attribute('color','inherit');
646               print $n->raw_attribute('color');               # 'red'
647
648       See also attribute().
649
650   raw_color_attribute()
651               # returns f.i. #ff0000
652               my $color = $graph->raw_color_attribute('color' );
653
654       Just like raw_attribute(), but only for colors, and returns them as
655       hex, using the current colorscheme.
656
657       If the attribute is not set on the object, returns "undef".
658
659   raw_attributes()
660               my $att = $object->raw_attributes();
661
662       Returns a hash with all the raw attributes of that object.  Attributes
663       that are no set on the object itself, but on the class this object
664       belongs to are not included.
665
666       This method respects inheritance, so an attribute value of 'inherit' on
667       an object will make the method return the inherited value.
668
669   set_attribute()
670               # Set the attribute on the given class.
671               $graph->set_attribute( $class, $name, $val );
672
673               # Set the attribute on the graph itself. This is synonymous
674               # to using 'graph' as class in the form above.
675               $graph->set_attribute( $name, $val );
676
677       Sets a given attribute named $name to the new value $val in the class
678       specified in $class.
679
680       Example:
681
682               $graph->set_attribute( 'graph', 'gid', '123' );
683
684       The class can be one of "graph", "edge", "node" or "group". The last
685       three can also have subclasses like in "node.subclassname".
686
687       You can also call the various attribute related methods on members of
688       the graph directly, for instance:
689
690               $node->set_attribute('label', 'my node');
691               $edge->set_attribute('color', 'red');
692               $group->set_attribute('fill', 'green');
693
694   set_attributes()
695               $graph->set_attributes( $class, $att );
696
697       Given a class name in $class and a hash of mappings between attribute
698       names and values in $att, will set all these attributes.
699
700       The class can be one of "graph", "edge", "node" or "group". The last
701       three can also have subclasses like in "node.subclassname".
702
703       Example:
704
705               $graph->set_attributes( 'node', { color => 'red', background => 'none' } );
706
707   del_attribute()
708               $graph->del_attribute('border');
709
710       Delete the attribute with the given name from the object.
711
712       You can also call the various attribute related methods on members of
713       the graph directly, for instance:
714
715               $node->del_attribute('label');
716               $edge->del_attribute('color');
717               $group->del_attribute('fill');
718
719   unquote_attribute()
720               # returns '"Hello World!"'
721               my $value = $self->unquote_attribute('node','label','"Hello World!"');
722               # returns 'red'
723               my $color = $self->unquote_attribute('node','color','"red"');
724
725       Return the attribute unquoted except for labels and titles, that is it
726       removes double quotes at the start and the end of the string, unless
727       these are escaped with a backslash.
728
729   border_attribute()
730               my $border = $graph->border_attribute();
731
732       Return the combined border attribute like "1px solid red" from the
733       border(style|color|width) attributes.
734
735   split_border_attributes()
736               my ($style,$width,$color) = $graph->split_border_attribute($border);
737
738       Split the border attribute (like "1px solid red") into the three
739       different parts.
740
741   quoted_comment()
742               my $cmt = $node->comment();
743
744       Comment of this object, quoted suitable as to be embedded into
745       HTML/SVG.  Returns the empty string if this object doesn't have a
746       comment set.
747
748   flow()
749               my $flow = $graph->flow();
750
751       Returns the flow of the graph, as absolute number in degress.
752
753   source_nodes()
754               my @roots = $graph->source_nodes();
755
756       Returns all nodes that have only outgoing edges, e.g. are the root of a
757       tree, in no particular order.
758
759       Isolated nodes (no edges at all) will not be included, see
760       predecessorless_nodes() to get these, too.
761
762       In scalar context, returns the number of source nodes.
763
764   predecessorless_nodes()
765               my @roots = $graph->predecessorless_nodes();
766
767       Returns all nodes that have no incoming edges, regardless of whether
768       they have outgoing edges or not, in no particular order.
769
770       Isolated nodes (no edges at all) will be included in the list.
771
772       See also source_nodes().
773
774       In scalar context, returns the number of predecessorless nodes.
775
776   root_node()
777               my $root = $graph->root_node();
778
779       Return the root node as Graph::Easy::Node object, if it was set with
780       the 'root' attribute.
781
782   timeout()
783               print $graph->timeout(), " seconds timeout for layouts.\n";
784               $graph->timeout(12);
785
786       Get/set the timeout for layouts in seconds. If the layout process did
787       not finish after that time, it will be stopped and a warning will be
788       printed.
789
790       The default timeout is 5 seconds.
791
792   strict()
793               print "Graph has strict checking\n" if $graph->strict();
794               $graph->strict(undef);          # disable strict attribute checks
795
796       Get/set the strict option. When set to a true value, all attribute
797       names and values will be strictly checked and unknown/invalid one will
798       be rejected.
799
800       This option is on by default.
801
802   type()
803               print "Graph is " . $graph->type() . "\n";
804
805       Returns the type of the graph as string, either "directed" or
806       "undirected".
807
808   layout()
809               $graph->layout();
810               $graph->layout( type => 'force', timeout => 60 );
811
812       Creates the internal structures to layout the graph.
813
814       This method will be called automatically when you call any of the
815       "as_FOO" methods or "output()" as described below.
816
817       The options are:
818
819               type            the type of the layout, possible values:
820                               'force'         - force based layouter
821                               'adhoc'         - the default layouter
822               timeout         timeout in seconds
823
824       See also: timeout().
825
826   output_format()
827               $graph->output_format('html');
828
829       Set the outputformat. One of 'html', 'ascii', 'graphviz', 'svg' or
830       'txt'.  See also output().
831
832   output()
833               my $out = $graph->output();
834
835       Output the graph in the format set by "output_format()".
836
837   as_ascii()
838               print $graph->as_ascii();
839
840       Return the graph layout in ASCII art, in utf-8.
841
842   as_ascii_file()
843               print $graph->as_ascii_file();
844
845       Is an alias for as_ascii.
846
847   as_ascii_html()
848               print $graph->as_ascii_html();
849
850       Return the graph layout in ASCII art, suitable to be embedded into an
851       HTML page. Basically it wraps the output from as_ascii() into "<pre>
852       </pre>" and inserts real HTML links. The returned string is in utf-8.
853
854   as_boxart()
855               print $graph->as_box();
856
857       Return the graph layout as box drawing using Unicode characters (in
858       utf-8, as always).
859
860   as_boxart_file()
861               print $graph->as_boxart_file();
862
863       Is an alias for "as_box".
864
865   as_boxart_html()
866               print $graph->as_boxart_html();
867
868       Return the graph layout as box drawing using Unicode characters, as
869       chunk that can be embedded into an HTML page.
870
871       Basically it wraps the output from as_boxart() into "<pre> </pre>" and
872       inserts real HTML links. The returned string is in utf-8.
873
874   as_boxart_html_file()
875               print $graph->as_boxart_html_file();
876
877       Return the graph layout as box drawing using Unicode characters, as a
878       full HTML page complete with header and footer.
879
880   as_html()
881               print $graph->as_html();
882
883       Return the graph layout as HTML section. See css() to get the CSS
884       section to go with that HTML code. If you want a complete HTML page
885       then use as_html_file().
886
887   as_html_page()
888               print $graph->as_html_page();
889
890       Is an alias for "as_html_file".
891
892   as_html_file()
893               print $graph->as_html_file();
894
895       Return the graph layout as HTML complete with headers, CSS section and
896       footer. Can be viewed in the browser of your choice.
897
898   add_group()
899               my $group = $graph->add_group('Group name');
900
901       Add a group to the graph and return it as Graph::Easy::Group object.
902
903   group()
904               my $group = $graph->group('Name');
905
906       Returns the group with the name "Name" as Graph::Easy::Group object.
907
908   rename_group()
909               $group = $graph->rename_group($group, $new_name);
910
911       Changes the name of the given group. If the passed group is not part of
912       this graph or just a string, it will be added with the new name to this
913       graph.
914
915       If the group was part of another graph, it will be deleted there and
916       added to this graph with the new name, effectively moving the group
917       from the old to the new graph and renaming it at the same time.
918
919   groups()
920               my @groups = $graph->groups();
921
922       Returns the groups of the graph as Graph::Easy::Group objects, in
923       arbitrary order.
924
925   groups_within()
926               # equivalent to $graph->groups():
927               my @groups = $graph->groups_within();           # all
928               my @toplevel_groups = $graph->groups_within(0); # level 0 only
929
930       Return the groups that are inside this graph, up to the specified
931       level, in arbitrary order.
932
933       The default level is -1, indicating no bounds and thus all contained
934       groups are returned.
935
936       A level of 0 means only the direct children, and hence only the
937       toplevel groups will be returned. A level 1 means the toplevel groups
938       and their toplevel children, and so on.
939
940   anon_groups()
941               my $anon_groups = $graph->anon_groups();
942
943       In scalar context, returns the number of anon groups (aka
944       Graph::Easy::Group::Anon) the graph has.
945
946       In list context, returns all anon groups as objects, in arbitrary
947       order.
948
949   del_group()
950               $graph->del_group($name);
951
952       Delete the group with the given name.
953
954   edges(), edges_within()
955               my @edges = $graph->edges();
956
957       Returns the edges of the graph as Graph::Easy::Edge objects, in
958       arbitrary order.
959
960       edges_within() is an alias for "edges()".
961
962   is_simple_graph(), is_simple()
963               if ($graph->is_simple())
964                 {
965                 }
966
967       Returns true if the graph does not have multiedges, e.g. if it does not
968       have more than one edge going from any node to any other node or group.
969
970       Since this method has to look at all edges, it is costly in terms of
971       both CPU and memory.
972
973   is_directed()
974               if ($graph->is_directed())
975                 {
976                 }
977
978       Returns true if the graph is directed.
979
980   is_undirected()
981               if ($graph->is_undirected())
982                 {
983                 }
984
985       Returns true if the graph is undirected.
986
987   parent()
988               my $parent = $graph->parent();
989
990       Returns the parent graph, for graphs this is undef.
991
992   label()
993               my $label = $graph->label();
994
995       Returns the label of the graph.
996
997   title()
998               my $title = $graph->title();
999
1000       Returns the (mouseover) title of the graph.
1001
1002   link()
1003               my $link = $graph->link();
1004
1005       Return a potential link (for the graphs label), build from the
1006       attributes "linkbase" and "link" (or autolink). Returns '' if there is
1007       no link.
1008
1009   as_graphviz()
1010               print $graph->as_graphviz();
1011
1012       Return the graph as graphviz code, suitable to be feed to a program
1013       like "dot" etc.
1014
1015   as_graphviz_file()
1016               print $graph->as_graphviz_file();
1017
1018       Is an alias for as_graphviz().
1019
1020   angle()
1021               my $degrees = Graph::Easy->angle( 'south' );
1022               my $degrees = Graph::Easy->angle( 120 );
1023
1024       Check an angle for being valid and return a value between -359 and 359
1025       degrees. The special values "south", "north", "west", "east", "up" and
1026       "down" are also valid and converted to degrees.
1027
1028   nodes()
1029               my $nodes = $graph->nodes();
1030
1031       In scalar context, returns the number of nodes/vertices the graph has.
1032
1033       In list context, returns all nodes as objects, in arbitrary order.
1034
1035   anon_nodes()
1036               my $anon_nodes = $graph->anon_nodes();
1037
1038       In scalar context, returns the number of anon nodes (aka
1039       Graph::Easy::Node::Anon) the graph has.
1040
1041       In list context, returns all anon nodes as objects, in arbitrary order.
1042
1043   html_page_header()
1044               my $header = $graph->html_page_header();
1045               my $header = $graph->html_page_header($css);
1046
1047       Return the header of an HTML page. Used together with html_page_footer
1048       by as_html_page to construct a complete HTML page.
1049
1050       Takes an optional parameter with the CSS styles to be inserted into the
1051       header. If $css is not defined, embedds the result of "$self->css()".
1052
1053   html_page_footer()
1054               my $footer = $graph->html_page_footer();
1055
1056       Return the footer of an HTML page. Used together with html_page_header
1057       by as_html_page to construct a complete HTML page.
1058
1059   css()
1060               my $css = $graph->css();
1061
1062       Return CSS code for that graph. See as_html().
1063
1064   as_txt()
1065               print $graph->as_txt();
1066
1067       Return the graph as a normalized textual representation, that can be
1068       parsed with Graph::Easy::Parser back to the same graph.
1069
1070       This does not call layout() since the actual text representation is
1071       just a dump of the graph.
1072
1073   as_txt_file()
1074               print $graph->as_txt_file();
1075
1076       Is an alias for as_txt().
1077
1078   as_svg()
1079               print $graph->as_svg();
1080
1081       Return the graph as SVG (Scalable Vector Graphics), which can be
1082       embedded into HTML pages. You need to install Graph::Easy::As_svg first
1083       to make this work.
1084
1085       See also as_svg_file().
1086
1087       Note: You need Graph::Easy::As_svg installed for this to work!
1088
1089   as_svg_file()
1090               print $graph->as_svg_file();
1091
1092       Returns SVG just like "as_svg()", but this time as standalone SVG,
1093       suitable for storing it in a file and referencing it externally.
1094
1095       After calling "as_svg_file()" or "as_svg()", you can retrieve some SVG
1096       information, notable "width" and "height" via "svg_information".
1097
1098       Note: You need Graph::Easy::As_svg installed for this to work!
1099
1100   svg_information()
1101               my $info = $graph->svg_information();
1102
1103               print "Size: $info->{width}, $info->{height}\n";
1104
1105       Return information about the graph created by the last "as_svg()" or
1106       "as_svg_file()" call.
1107
1108       The following fields are set:
1109
1110               width           width of the SVG in pixels
1111               height          height of the SVG in pixels
1112
1113       Note: You need Graph::Easy::As_svg installed for this to work!
1114
1115   as_vcg()
1116               print $graph->as_vcg();
1117
1118       Return the graph as VCG text. VCG is a subset of GDL (Graph Description
1119       Language).
1120
1121       This does not call layout() since the actual text representation is
1122       just a dump of the graph.
1123
1124   as_vcg_file()
1125               print $graph->as_vcg_file();
1126
1127       Is an alias for as_vcg().
1128
1129   as_gdl()
1130               print $graph->as_gdl();
1131
1132       Return the graph as GDL (Graph Description Language) text. GDL is a
1133       superset of VCG.
1134
1135       This does not call layout() since the actual text representation is
1136       just a dump of the graph.
1137
1138   as_gdl_file()
1139               print $graph->as_gdl_file();
1140
1141       Is an alias for as_gdl().
1142
1143   as_graphml()
1144               print $graph->as_graphml();
1145
1146       Return the graph as a GraphML representation.
1147
1148       This does not call layout() since the actual text representation is
1149       just a dump of the graph.
1150
1151       The output contains only the set attributes, e.g. default attribute
1152       values are not specifically mentioned. The attribute names and values
1153       are the in the format that "Graph::Easy" defines.
1154
1155   as_graphml_file()
1156               print $graph->as_graphml_file();
1157
1158       Is an alias for as_graphml().
1159
1160   sorted_nodes()
1161               my $nodes =
1162                $graph->sorted_nodes( );               # default sort on 'id'
1163               my $nodes =
1164                $graph->sorted_nodes( 'name' );        # sort on 'name'
1165               my $nodes =
1166                $graph->sorted_nodes( 'layer', 'id' ); # sort on 'layer', then on 'id'
1167
1168       In scalar context, returns the number of nodes/vertices the graph has.
1169       In list context returns a list of all the node objects (as reference),
1170       sorted by their attribute(s) given as arguments. The default is 'id',
1171       e.g. their internal ID number, which amounts more or less to the order
1172       they have been inserted.
1173
1174       This routine will sort the nodes by their group first, so the requested
1175       sort order will be only valid if there are no groups or inside each
1176       group.
1177
1178   as_debug()
1179               print $graph->as_debug();
1180
1181       Return debugging information like version numbers of used modules, and
1182       a textual representation of the graph.
1183
1184       This does not call layout() since the actual text representation is
1185       more a dump of the graph, than a certain layout.
1186
1187   node()
1188               my $node = $graph->node('node name');
1189
1190       Return node by unique name (case sensitive). Returns undef if the node
1191       does not exist in the graph.
1192
1193   edge()
1194               my $edge = $graph->edge( $x, $y );
1195
1196       Returns the edge objects between nodes $x and $y. Both $x and $y can be
1197       either scalars with names or "Graph::Easy::Node" objects.
1198
1199       Returns undef if the edge does not yet exist.
1200
1201       In list context it will return all edges from $x to $y, in scalar
1202       context it will return only one (arbitrary) edge.
1203
1204   id()
1205               my $graph_id = $graph->id();
1206               $graph->id('123');
1207
1208       Returns the id of the graph. You can also set a new ID with this
1209       routine. The default is ''.
1210
1211       The graph's ID is used to generate unique CSS classes for each graph,
1212       in the case you want to have more than one graph in an HTML page.
1213
1214   seed()
1215               my $seed = $graph->seed();
1216               $graph->seed(2);
1217
1218       Get/set the random seed for the graph object. See randomize() for a
1219       method to set a random seed.
1220
1221       The seed is used to create random numbers for the layouter. For the
1222       same graph, the same seed will always lead to the same layout.
1223
1224   randomize()
1225               $graph->randomize();
1226
1227       Set a random seed for the graph object. See seed().
1228
1229   debug()
1230               my $debug = $graph->debug();    # get
1231               $graph->debug(1);               # enable
1232               $graph->debug(0);               # disable
1233
1234       Enable, disable or read out the debug status. When the debug status is
1235       true, additional debug messages will be printed on STDERR.
1236
1237   score()
1238               my $score = $graph->score();
1239
1240       Returns the score of the graph, or undef if layout() has not yet been
1241       called.
1242
1243       Higher scores are better, although you cannot compare scores for
1244       different graphs. The score should only be used to compare different
1245       layouts of the same graph against each other:
1246
1247               my $max = undef;
1248
1249               $graph->randomize();
1250               my $seed = $graph->seed();
1251
1252               $graph->layout();
1253               $max = $graph->score();
1254
1255               for (1..10)
1256                 {
1257                 $graph->randomize();                  # select random seed
1258                 $graph->layout();                     # layout with that seed
1259                 if ($graph->score() > $max)
1260                   {
1261                   $max = $graph->score();             # store the new max store
1262                   $seed = $graph->seed();             # and it's seed
1263                   }
1264                 }
1265
1266               # redo the best layout
1267               if ($seed ne $graph->seed())
1268                 {
1269                 $graph->seed($seed);
1270                 $graph->layout();
1271                 }
1272               # output graph:
1273               print $graph->as_ascii();               # or as_html() etc
1274
1275   valid_attribute()
1276               my $graph = Graph::Easy->new();
1277               my $new_value =
1278                 $graph->valid_attribute( $name, $value, $class );
1279
1280               if (ref($new_value) eq 'ARRAY' && @$new_value == 0)
1281                 {
1282                 # throw error
1283                 die ("'$name' is not a valid attribute name for '$class'")
1284                       if $self->{_warn_on_unused_attributes};
1285                 }
1286               elsif (!defined $new_value)
1287                 {
1288                 # throw error
1289                 die ("'$value' is no valid '$name' for '$class'");
1290                 }
1291
1292       Deprecated, please use validate_attribute().
1293
1294       Check that a "$name,$value" pair is a valid attribute in class $class,
1295       and returns a new value.
1296
1297       It returns an array ref if the attribute name is invalid, and undef if
1298       the value is invalid.
1299
1300       The return value can differ from the passed in value, f.i.:
1301
1302               print $graph->valid_attribute( 'color', 'red' );
1303
1304       This would print '#ff0000';
1305
1306   validate_attribute()
1307               my $graph = Graph::Easy->new();
1308               my ($rc,$new_name, $new_value) =
1309                 $graph->validate_attribute( $name, $value, $class );
1310
1311       Checks a given attribute name and value (or values, in case of a value
1312       like "red|green") for being valid. It returns a new attribute name (in
1313       case of "font-color" => "fontcolor") and either a single new attribute,
1314       or a list of attribute values as array ref.
1315
1316       If $rc is defined, it is the error number:
1317
1318               1                       unknown attribute name
1319               2                       invalid attribute value
1320               4                       found multiple attributes, but these arent
1321                                       allowed at this place
1322
1323   color_as_hex()
1324               my $hexred   = Graph::Easy->color_as_hex( 'red' );
1325               my $hexblue  = Graph::Easy->color_as_hex( '#0000ff' );
1326               my $hexcyan  = Graph::Easy->color_as_hex( '#f0f' );
1327               my $hexgreen = Graph::Easy->color_as_hex( 'rgb(0,255,0)' );
1328
1329       Takes a valid color name or definition (hex, short hex, or RGB) and
1330       returns the color in hex like "#ff00ff".
1331
1332   color_value($color_name, $color_scheme)
1333               my $color = Graph::Easy->color_name( 'red' );   # #ff0000
1334               print Graph::Easy->color_name( '#ff0000' );     # #ff0000
1335
1336               print Graph::Easy->color_name( 'snow', 'x11' );
1337
1338       Given a color name, returns the color in hex. See color_name for a list
1339       of possible values for the optional $color_scheme parameter.
1340
1341   color_name($color_value, $color_scheme)
1342               my $color = Graph::Easy->color_name( 'red' );   # red
1343               print Graph::Easy->color_name( '#ff0000' );     # red
1344
1345               print Graph::Easy->color_name( 'snow', 'x11' );
1346
1347       Takes a hex color value and returns the name of the color.
1348
1349       The optional parameter is the color scheme, where the following values
1350       are possible:
1351
1352        w3c                    (the default)
1353        x11                    (what graphviz uses as default)
1354
1355       Plus the following ColorBrewer schemes are supported, see the online
1356       manual for examples and their usage:
1357
1358        accent3 accent4 accent5 accent6 accent7 accent8
1359
1360        blues3 blues4 blues5 blues6 blues7 blues8 blues9
1361
1362        brbg3 brbg4 brbg5 brbg6 brbg7 brbg8 brbg9 brbg10 brbg11
1363
1364        bugn3 bugn4 bugn5 bugn6 bugn7 bugn8 bugn9 bupu3 bupu4 bupu5 bupu6 bupu7
1365        bupu8 bupu9
1366
1367        dark23 dark24 dark25 dark26 dark27 dark28
1368
1369        gnbu3 gnbu4 gnbu5 gnbu6 gnbu7 gnbu8 gnbu9
1370
1371        greens3 greens4 greens5 greens6 greens7 greens8 greens9
1372
1373        greys3 greys4 greys5 greys6 greys7 greys8 greys9
1374
1375        oranges3 oranges4 oranges5 oranges6 oranges7 oranges8 oranges9
1376
1377        orrd3 orrd4 orrd5 orrd6 orrd7 orrd8 orrd9
1378
1379        paired3 paired4 paired5 paired6 paired7 paired8 paired9 paired10 paired11
1380        paired12
1381
1382        pastel13 pastel14 pastel15 pastel16 pastel17 pastel18 pastel19
1383
1384        pastel23 pastel24 pastel25 pastel26 pastel27 pastel28
1385
1386        piyg3 piyg4 piyg5 piyg6 piyg7 piyg8 piyg9 piyg10 piyg11
1387
1388        prgn3 prgn4 prgn5 prgn6 prgn7 prgn8 prgn9 prgn10 prgn11
1389
1390        pubu3 pubu4 pubu5 pubu6 pubu7 pubu8 pubu9
1391
1392        pubugn3 pubugn4 pubugn5 pubugn6 pubugn7 pubugn8 pubugn9
1393
1394        puor3 puor4 puor5 puor6 puor7 puor8 puor9 puor10 puor11
1395
1396        purd3 purd4 purd5 purd6 purd7 purd8 purd9
1397
1398        purples3 purples4 purples5 purples6 purples7 purples8 purples9
1399
1400        rdbu3 rdbu4 rdbu5 rdbu6 rdbu7 rdbu8 rdbu9 rdbu10 rdbu11
1401
1402        rdgy3 rdgy4 rdgy5 rdgy6 rdgy7 rdgy8 rdgy9
1403
1404        rdpu3 rdpu4 rdpu5 rdpu6 rdpu7 rdpu8 rdpu9 rdgy10 rdgy11
1405
1406        rdylbu3 rdylbu4 rdylbu5 rdylbu6 rdylbu7 rdylbu8 rdylbu9 rdylbu10 rdylbu11
1407
1408        rdylgn3 rdylgn4 rdylgn5 rdylgn6 rdylgn7 rdylgn8 rdylgn9 rdylgn10 rdylgn11
1409
1410        reds3 reds4 reds5 reds6 reds7 reds8 reds9
1411
1412        set13 set14 set15 set16 set17 set18 set19
1413
1414        set23 set24 set25 set26 set27 set28
1415
1416        set33 set34 set35 set36 set37 set38 set39 set310 set311 set312
1417
1418        spectral3 spectral4 spectral5 spectral6 spectral7 spectral8 spectral9
1419        spectral10 spectral11
1420
1421        ylgn3 ylgn4 ylgn5 ylgn6 ylgn7 ylgn8 ylgn9
1422
1423        ylgnbu3 ylgnbu4 ylgnbu5 ylgnbu6 ylgnbu7 ylgnbu8 ylgnbu9
1424
1425        ylorbr3 ylorbr4 ylorbr5 ylorbr6 ylorbr7 ylorbr8 ylorbr9
1426
1427        ylorrd3 ylorrd4 ylorrd5 ylorrd6 ylorrd7 ylorrd8 ylorrd9
1428
1429   color_names()
1430               my $names = Graph::Easy->color_names();
1431
1432       Return a hash with name => value mapping for all known colors.
1433
1434   text_style()
1435               if ($graph->text_style('bold, italic'))
1436                 {
1437                 ...
1438                 }
1439
1440       Checks the given style list for being valid.
1441
1442   text_styles()
1443               my $styles = $graph->text_styles();     # or $edge->text_styles() etc.
1444
1445               if ($styles->{'italic'})
1446                 {
1447                 print 'is italic\n';
1448                 }
1449
1450       Return a hash with the given text-style properties, aka 'underline',
1451       'bold' etc.
1452
1453   text_styles_as_css()
1454               my $styles = $graph->text_styles_as_css();      # or $edge->...() etc.
1455
1456       Return the text styles as a chunk of CSS styling that can be embedded
1457       into a " style="" " parameter.
1458
1459   use_class()
1460               $graph->use_class('node', 'Graph::Easy::MyNode');
1461
1462       Override the class to be used to constructs objects when calling
1463       "add_edge()", "add_group()" or "add_node()".
1464
1465       The first parameter can be one of the following:
1466
1467               node
1468               edge
1469               group
1470
1471       Please see the documentation about "use_class()" in
1472       "Graph::Easy::Parser" for examples and details.
1473
1474   animation_as_graph()
1475               my $graph_2 = $graph->animation_as_graph();
1476               print $graph_2->as_ascii();
1477
1478       Returns the animation of $graph as a graph describing the flow of the
1479       animation. Useful for debugging animation flows.
1480
1481   add_cycle()
1482               $graph->add_cycle('A','B','C');         # A -> B -> C -> A
1483
1484       Compatibility method for Graph, adds the edges between each node and
1485       back from the last node to the first. Returns the graph.
1486
1487   add_path()
1488               $graph->add_path('A','B','C');          # A -> B -> C
1489
1490       Compatibility method for Graph, adds the edges between each node.
1491       Returns the graph.
1492
1493   add_vertex()
1494               $graph->add_vertex('A');
1495
1496       Compatibility method for Graph, adds the node and returns the graph.
1497
1498   add_vertices()
1499               $graph->add_vertices('A','B');
1500
1501       Compatibility method for Graph, adds these nodes and returns the graph.
1502
1503   has_edge()
1504               $graph->has_edge('A','B');
1505
1506       Compatibility method for Graph, returns true if at least one edge
1507       between A and B exists.
1508
1509   vertices()
1510       Compatibility method for Graph, returns in scalar context the number of
1511       nodes this graph has, in list context a (arbitrarily sorted) list of
1512       node objects.
1513
1514   set_vertex_attribute()
1515               $graph->set_vertex_attribute( 'A', 'fill', '#deadff' );
1516
1517       Compatibility method for Graph, set the named vertex attribute.
1518
1519       Please note that this routine will only accept Graph::Easy attribute
1520       names and values. If you want to attach custom attributes, you need to
1521       start their name with 'x-':
1522
1523               $graph->set_vertex_attribute( 'A', 'x-foo', 'bar' );
1524
1525   get_vertex_attribute()
1526               my $fill = $graph->get_vertex_attribute( 'A', 'fill' );
1527
1528       Compatibility method for Graph, get the named vertex attribute.
1529
1530       Please note that this routine will only accept Graph::Easy attribute
1531       names. See set_vertex_attribute().
1532

EXPORT

1534       Exports nothing.
1535

SEE ALSO

1537       Graph, Graph::Convert, Graph::Easy::As_svg, Graph::Easy::Manual and
1538       Graph::Easy::Parser.
1539
1540   Related Projects
1541       Graph::Layout::Aesthetic, Graph and Text::Flowchart.
1542
1543       There is also an very old, unrelated project from ca. 1995, which does
1544       something similar.  See
1545       <http://rw4.cs.uni-sb.de/users/sander/html/gsvcg1.html>.
1546
1547       Testcases and more examples under:
1548
1549       <http://bloodgate.com/perl/graph/>.
1550

LIMITATIONS

1552       This module is now quite complete, but there are still some
1553       limitations.  Hopefully further development will lift these.
1554
1555   Scoring
1556       Scoring is not yet implemented, each generated graph will be the same
1557       regardless of the random seed.
1558
1559   Layouter
1560       The layouter can not yet handle links between groups (or between a
1561       group and a node, or vice versa). These links will thus only appear in
1562       as_graphviz() or as_txt() output.
1563
1564   Paths
1565       No optimizations
1566         In complex graphs, non-optimal layout part like this one might
1567         appear:
1568
1569                 +------+     +--------+
1570                 | Bonn | --> | Berlin | --> ...
1571                 +------+     +--------+
1572                                ^
1573                                |
1574                                |
1575                 +---------+    |
1576                 | Kassel  | ---+
1577                 +---------+
1578
1579         A second-stage optimizer that simplifies these layouts is not yet
1580         implemented.
1581
1582         In addition the general placement/processing strategy as well as the
1583         local strategy might be improved.
1584
1585       attributes
1586         The following attributes are currently ignored by the layouter:
1587
1588                 undirected graphs
1589                 autosplit/autojoin for edges
1590                 tail/head label/title/link for edges
1591
1592       groups
1593         The layouter is not fully recursive yet, so groups do not properly
1594         nest.
1595
1596         In addition, links to/from groups are missing, too.
1597
1598   Output formats
1599       Some output formats are not yet complete in their implementation.
1600       Please see the online manual at
1601       <http://bloodgate.com/perl/graph/manual> under "Output" for details.
1602

LICENSE

1604       This library is free software; you can redistribute it and/or modify it
1605       under the terms of the GPL 2.0 or a later version.
1606
1607       See the LICENSE file for a copy of the GPL.
1608
1609       This product includes color specifications and designs developed by
1610       Cynthia Brewer (http://colorbrewer.org/). See the LICENSE file for the
1611       full license text that applies to these color schemes.
1612

NAME CHANGE

1614       The package was formerly known as "Graph::Simple". The name was changed
1615       for two reasons:
1616
1617       · In graph theory, a "simple" graph is a special type of graph. This
1618         software, however, supports more than simple graphs.
1619
1620       · Creating graphs should be easy even when the graphs are quite
1621         complex.
1622

AUTHOR

1624       Copyright (C) 2004 - 2008 by Tels <http://bloodgate.com>
1625
1626perl v5.32.0                      2020-07-28                    Graph::Easy(3)
Impressum