Question

Imagine I have an array of data. Each item in it is another array containing ‘id’, ‘link’ and ‘display’:

$travel = array(
    array(
        'id' => 1,
        'link' => 'bus',
        'display' => 'bus'
    ),
    array(
        'id' => 2,
        'link' => 'bike',
        'display' => 'bicycle'
    ),
    array(
        'id' => 3,
        'link' => 'cart',
        'display' => 'horse and cart'
    )
);

To display ‘display’ by a known id ($id) I would need to do something like:

foreach($travel as $t) {
    if($t['id'] == $id) {
        echo $t['display'];
        break;  // uuurgh, nasty...
    }
}

Equally, to display ‘display’ by a known link ($link) I would need to do the same:

foreach($travel as $t) {
    if($t['link'] == $link) {
        echo $t['display'];
        break;
    }
}

To be more efficient I could create two similar arrays:

$travelID = array(
    1 => array(
        'link' => 'bus',
        'display' => 'bus'
    ),
    2 => array(
        'link' => 'bike',
        'display' => 'bicycle'
    ),
    3 => array(
        'link' => 'cart',
        'display' => 'horse and cart'
    )
);

$travelLink = array(
    'bus' => array(
        'id' => 1,
        'display' => 'bus'
    ),
    'bike' => array(
        'id' => 2,
        'display' => 'bicycle'
    ),
    'cart' => array(
        'id' => 3,
        'display' => 'horse and cart'
    )
);

and then perform the following:

echo $travelID[$id]['display'];
echo $travelLink[$link]['display'];

But is there a way of keeping all the data together whilst still being able to reference it simply/quickly?

Answer 1

    $keys = array('id', 'link');
    $multiple_key_array = new MultipleKeyArray($keys);

    $data_1 = array('id' => 1, 'link' => 'bus', 'display' => 'bus');
    $multiple_key_array->addData($data_1);

    $data_2 = array('id' => 2, 'link' => 'bike', 'display' => 'bicycle');
    $multiple_key_array->addData($data_2);

    $data_3 = array('id' => 3, 'link' => 'cart', 'display' => 'horse and cart');
    $multiple_key_array->addData($data_3);

    var_dump($multiple_key_array->getData('id', 1));

class MultipleKeyArray{

    private $data_array     = array();
    private $key_array      = array();
    private $map_array      = array();

    public function __construct($key_array){

        $this->key_array = $key_array;

    }

    public function addData($data_array){

        $index = count($this->data_array);
        $this->data_array[] = $data_array;


        foreach($this->key_array as $key){

            if(array_key_exists($key, $data_array)){

                $this->map_array[$key][$data_array[$key]] = $index;

            }

        }

    }

    public function getData($key, $value){

        $index = $this->map_array[$key][$value];
        return $this->data_array[$index];

    }

}