/**
* checks whether this vertex has a loop (edge to itself)
*
* @return boolean
* @uses Edge::isLoop()
*/
public function hasLoopVertex(Vertex $vertex)
{
foreach ($vertex->getEdges() as $edge) {
if ($edge->isLoop()) {
return true;
}
}
return false;
}
/**
* @param Vertex $vertex
* @return \Fhaculty\Graph\Edge\Directed
*/
private function createEdgeToAdtRootVertexBy(Vertex $vertex)
{
foreach ($this->adtRootVertex->getEdges() as $edge) {
/** @var \Fhaculty\Graph\Edge\Directed $edge */
if ($edge->isConnection($this->adtRootVertex, $vertex)) {
return $edge;
}
}
return $this->adtRootVertex->createEdgeTo($vertex);
}
/**
* Calculates the flow for this Vertex: sum(outflow) - sum(inflow)
*
* Usually, vertices should have a resulting flow of 0: The sum of flows
* entering a vertex must equal the sum of flows leaving a vertex. If the
* resulting flow is < 0, this vertex is considered a sink (i.e. there's
* more flow into this vertex). If the resulting flow is > 0, this vertex
* is considered a "source" (i.e. there's more flow leaving this vertex).
*
* @param Vertex $vertex
* @return float
* @throws UnexpectedValueException if they are undirected edges
* @see Vertex::getBalance()
* @uses Vertex::getEdges()
* @uses Edge::getFlow()
*/
public function getFlowVertex(Vertex $vertex)
{
$sumOfFlow = 0;
foreach ($vertex->getEdges() as $edge) {
if (!$edge instanceof EdgeDirected) {
throw new UnexpectedValueException("TODO: undirected edges not suported yet");
}
// edge is an outgoing edge of this vertex
if ($edge->hasVertexStart($vertex)) {
// flowing out (flow is "pointing away")
$sumOfFlow += $edge->getFlow();
// this is an ingoing edge
} else {
// flowing in
$sumOfFlow -= $edge->getFlow();
}
}
return $sumOfFlow;
}
/**
* get neighbor vertices for given start vertex
*
* @param Vertex $vertex
* @throws UnexpectedValueException for directed edges
* @return Vertices (might include possible duplicates)
* @uses Vertex::getEdges()
* @uses Edge::getVertexToFrom()
* @see Vertex::getVerticesEdge()
*/
private function getVerticesNeighbor(Vertex $vertex)
{
$vertices = array();
foreach ($vertex->getEdges() as $edge) {
/* @var Edge $edge */
if (!$edge instanceof UndirectedEdge) {
throw new UnexpectedValueException('Directed edge encountered');
}
$vertices[] = $edge->getVertexToFrom($vertex);
}
return new Vertices($vertices);
}
/**
* get outdegree of this vertex (number of edges FROM this vertex TO other vertices)
*
* @param Vertex $vertex
* @return int
* @uses Edge::hasVertexStart()
* @see self::getDegreeVertex()
*/
public function getDegreeOutVertex(Vertex $vertex)
{
$n = 0;
foreach ($vertex->getEdges() as $edge) {
if ($edge->hasVertexStart($vertex)) {
++$n;
}
}
return $n;
}
