- var_dump: documentation ( source)
- array_combine: documentation ( source)
- array_filter: documentation ( source)
<?php
$array = ['first', 'luke', 'last', 'lancaster'];
$odd=array_filter($array, function ($input) {return $input & 1;});
$even=array_filter($array, function ($input) {return !($input & 1);});
$combined = array_combine($odd, $even);
var_dump($combined);