Every element in this library can contain attributes. Attributes are just meta-data attached to the element and used by the end user.

Attributes are available for Graph, Edge\Set, Edge, Vertex\Set and Vertex. To be sure that an object allows attributes, than check if it implements the Bisarca\Graph\Attribute\AttributeAwareInterface interface.

Note: For a rapid implementation, use the Bisarca\Graph\Attribute\AttributeAwareTrait trait.

The attributes are like elements in an array, so they are defined with a string key and a variable value.

$vertex->setAttribute('id', 'n0');

if ($graph->hasAttribute('name')) {
    var_dump($graph->getAttribute('name')); // string(11) "lorem ipsum"
}

$edge->removeAttribute('label');

// $vertex1 has a name and a color

var_dump($vertex1->getAttributes());
// array(2) {
//   'name' =>
//   string(11) "lorem ipsum"
//   'color' =>
//   string(5) "green"
// }

// remove all the attributes
$vertex1->clearAttributes();

// give me the vertex name of "undefined" (by default it's null)
var_dump($vertex1->getAttribute('name', 'undefined')) // string(9) "undefined"

if ($vertex1->isEmptyAttributes()) {
    // ...
}