Fixed subgroup and add rank

[Yahasana]

subgroup should include edges and rank

[clue]

Hi @Yahasana, thanks for taking the time to file this PR! 👍

Unfortunately, the PR does not contain any documentation or tests, so it's a bit unclear what you're trying to achieve from the snippet you've posted.

May I ask you provide a simple gist of what you're trying to achieve and how this looks from a consumer perspective? Thanks!

[Yahasana]

@clue group and rank can create a table like vertexes graph, which are align in rows and column 🆒

$i0 = $graph->createVertex(['graphviz.group' => 'g0']);
$i1 = $graph->createVertex(['graphviz.group' => 'g0']);
$i2 = $graph->createVertex(['graphviz.group' => 'g0']);
$j0 = $graph->createVertex(['graphviz.group' => 'g1']);
$j1 = $graph->createVertex(['graphviz.group' => 'g1']);
$j2 = $graph->createVertex(['graphviz.group' => 'g1']);

$graphviz->setRanks(0, [$i0, $i1, $i2])
    ->setRanks(1, [$j0, $j1, $j2]);

[Yahasana]

One more thing, there is a fail test case because of i make escape id simple for better performance. people want to use special chars in the id get trouble themselves. i'll not be goin to fix it

[clue]

@Yahasana Thanks for the background info!

This is definitely an interesting feature addition and I would love to see this supported in this project. That being said, I'm not sure about the best API. In particular, this seems to be somewhat related to #38, so I wonder if we can come up with a consistent API.

What do you think?

[Yahasana]

How about to change API look like this one?

$i0 = $graph->createVertex(['graphviz.group' => 'g0', 'graphviz.rank' => 0]);
$i1 = $graph->createVertex(['graphviz.group' => 'g0', 'graphviz.rank' => 0]);
$i2 = $graph->createVertex(['graphviz.group' => 'g0', 'graphviz.rank' => 0]);
$j0 = $graph->createVertex(['graphviz.group' => 'g1', 'graphviz.rank' => 1]);
$j1 = $graph->createVertex(['graphviz.group' => 'g1', 'graphviz.rank' => 1]);
$j2 = $graph->createVertex(['graphviz.group' => 'g1', 'graphviz.rank' => 1]);

the same as

$v = $graph->createVertex();
$v->setAttribute('graphviz.group', 'g0');
$v->setAttribute('graphviz.rank', 0);