- var_dump: documentation ( source)
- array_intersect_key: documentation ( source)
- array_flip: documentation ( source)
<?php
$array1 = array('description' => 'desc bla bla bla', 'summary' => 'summary bla bla bla', 'usage' => 'usage bla bla bla');
$array2 = array('description', 'summary');
$array_intersected = array_intersect_key(array_flip($array1), $array2);
var_dump($array_intersected);