- var_dump: documentation ( source)
- array_reduce: documentation ( source)
<?php
$arr = array('a','b','c','d');
$assoc_arr = array_reduce($arr, function ($result, $item) {
$result[$item] = (($item == 'a') || ($item == 'c')) ? 'yes' : 'no';
return $result;
}, array());
var_dump($assoc_arr);