- array_column: documentation ( source)
- print_r: documentation ( source)
- array_merge: documentation ( source)
<?php
$testArray = array('test' => array('a' => array('percy', 'a' => 'mitch'), 'b' => array('test', 'hello'), 'c'));
$res = array_merge(array_column($testArray, 'a'), array_column($testArray, 'b'), array('x' => array('ex'),'y' => 'why','z' => 'zee'));
print_r($res);