/**
* A subgraph is calculated based on the participants collected based on the given node ids.
*
* @param array $ids
* The nodes interested in.
* @return DirectedGraph
* The subgraph with all participants
*/
public function subGraph($ids = array())
{
$g = new DirectedGraph();
$participants = $this->getParticipants($ids);
foreach ($participants as $id) {
$g->addNode($id);
// Only participating links are added.
$links = $this->getLinks($id);
if (is_array($links)) {
$g->addLinks($id, array_intersect($participants, $links));
}
}
return $g;
}
/**
* Converts a DirectedGraph into a DirectedAcyclicGraph.
*
* A DirectedGraph can be converted into a DirectedAcyclicGraph when
* is does not contain any cycle.
*
* @param \GraphAPI\Component\Graph\DirectedGraph $g
* @param type $ignore_exception
* @throws \GraphAPI\Component\Graph\Exception
*/
static function fromDirectedGraph(DirectedGraph $g, $ignore_exception = FALSE)
{
$d = new DirectedAcyclicGraph();
foreach ($g->getNodeIds() as $id) {
$links = $g->getLinks($id);
foreach ($links as $link) {
try {
$d->addLink($id, $link);
} catch (\Exception $exc) {
if (!$ignore_exception) {
throw $exc;
}
}
}
}
return $d;
}
function dumpReverse(DirectedGraph $g)
{
echo "\nReversed: " . $g->getReversedGraph() . "\n";
}