Turn on/off the option to only display nodes and edges with labels
When this option is turned on, then only nodes (resources and literals) and edges (properties) will only be displayed if they have a label. You can use this option, to create concise, diagrams of your data, rather than the RDF.
This option is turned off by default.
bool $onlyLabelled A boolean value to enable/display only labelled items:
object EasyRdf_Serialiser_GraphViz
public function setOnlyLabelled($onlyLabelled) {
$this->onlyLabelled = $onlyLabelled;
return $this;
}