/**
* check whether this graph has an eulerian cycle
*
* @return boolean
* @uses ConnectedComponents::isSingle()
* @uses Degree::getDegreeVertex()
* @todo isolated vertices should be ignored
* @todo definition is only valid for undirected graphs
*/
public function hasCycle()
{
$components = new ConnectedComponents($this->graph);
if ($components->isSingle()) {
$alg = new Degree($this->graph);
foreach ($this->graph->getVertices() as $vertex) {
// uneven degree => fail
if ($alg->getDegreeVertex($vertex) & 1) {
return false;
}
}
return true;
}
return false;
}
public function testGraphIrregular()
{
// 1 -> 2 -> 3
$graph = new Graph();
$v1 = $graph->createVertex(1);
$v2 = $graph->createVertex(2);
$v3 = $graph->createVertex(3);
$v1->createEdgeTo($v2);
$v2->createEdgeTo($v3);
$alg = new AlgorithmDegree($graph);
try {
$this->assertEquals(0, $alg->getDegree());
$this->fail();
} catch (UnexpectedValueException $e) {
}
$this->assertEquals(1, $alg->getDegreeMin());
$this->assertEquals(2, $alg->getDegreeMax());
$this->assertFalse($alg->isRegular());
$this->assertFalse($alg->isBalanced());
$this->assertEquals(0, $alg->getDegreeInVertex($v1));
$this->assertEquals(1, $alg->getDegreeOutVertex($v1));
$this->assertEquals(1, $alg->getDegreeVertex($v1));
$this->assertFalse($alg->isVertexIsolated($v1));
$this->assertFalse($alg->isVertexSink($v1));
$this->assertTrue($alg->isVertexSource($v1));
$this->assertEquals(1, $alg->getDegreeInVertex($v2));
$this->assertEquals(1, $alg->getDegreeOutVertex($v2));
$this->assertEquals(2, $alg->getDegreeVertex($v2));
$this->assertFalse($alg->isVertexIsolated($v2));
$this->assertFalse($alg->isVertexSink($v2));
$this->assertFalse($alg->isVertexSource($v2));
$this->assertEquals(1, $alg->getDegreeInVertex($v3));
$this->assertEquals(0, $alg->getDegreeOutVertex($v3));
$this->assertEquals(1, $alg->getDegreeVertex($v3));
$this->assertFalse($alg->isVertexIsolated($v3));
$this->assertTrue($alg->isVertexSink($v3));
$this->assertFalse($alg->isVertexSource($v3));
}
/**
* create graphviz script representing this graph
*
* @return string
* @uses Directed::hasDirected()
* @uses Graph::getVertices()
* @uses Graph::getEdges()
*/
public function createScript()
{
$alg = new Directed($this->graph);
$directed = $alg->hasDirected();
$script = ($directed ? 'di' : '') . 'graph G {' . self::EOL;
// add global attributes
$layout = $this->graph->getLayout();
if ($layout) {
$script .= $this->formatIndent . 'graph ' . $this->escapeAttributes($layout) . self::EOL;
}
if ($this->layoutVertex) {
$script .= $this->formatIndent . 'node ' . $this->escapeAttributes($this->layoutVertex) . self::EOL;
}
if ($this->layoutEdge) {
$script .= $this->formatIndent . 'edge ' . $this->escapeAttributes($this->layoutEdge) . self::EOL;
}
$alg = new Groups($this->graph);
// only append group number to vertex label if there are at least 2 different groups
$showGroups = $alg->getNumberOfGroups() > 1;
if ($showGroups) {
$gid = 0;
$indent = str_repeat($this->formatIndent, 2);
// put each group of vertices in a separate subgraph cluster
foreach ($alg->getGroups() as $group) {
$script .= $this->formatIndent . 'subgraph cluster_' . $gid++ . ' {' . self::EOL . $indent . 'label = ' . $this->escape($group) . self::EOL;
foreach ($alg->getVerticesGroup($group)->getMap() as $vid => $vertex) {
$layout = $this->getLayoutVertex($vertex);
$script .= $indent . $this->escapeId($vid);
if ($layout) {
$script .= ' ' . $this->escapeAttributes($layout);
}
$script .= self::EOL;
}
$script .= ' }' . self::EOL;
}
} else {
$alg = new Degree($this->graph);
// explicitly add all isolated vertices (vertices with no edges) and vertices with special layout set
// other vertices wil be added automatically due to below edge definitions
foreach ($this->graph->getVertices()->getMap() as $vid => $vertex) {
$layout = $this->getLayoutVertex($vertex);
if ($layout || $alg->isVertexIsolated($vertex)) {
$script .= $this->formatIndent . $this->escapeId($vid);
if ($layout) {
$script .= ' ' . $this->escapeAttributes($layout);
}
$script .= self::EOL;
}
}
}
$edgeop = $directed ? ' -> ' : ' -- ';
// add all edges as directed edges
foreach ($this->graph->getEdges() as $currentEdge) {
$both = $currentEdge->getVertices()->getVector();
$currentStartVertex = $both[0];
$currentTargetVertex = $both[1];
$script .= $this->formatIndent . $this->escapeId($currentStartVertex->getId()) . $edgeop . $this->escapeId($currentTargetVertex->getId());
$layout = $this->getLayoutEdge($currentEdge);
// this edge also points to the opposite direction => this is actually an undirected edge
if ($directed && $currentEdge->isConnection($currentTargetVertex, $currentStartVertex)) {
$layout['dir'] = 'none';
}
if ($layout) {
$script .= ' ' . $this->escapeAttributes($layout);
}
$script .= self::EOL;
}
$script .= '}' . self::EOL;
return $script;
}
