- array_column: documentation ( source)
- print_r: documentation ( source)
<?php
$arr = Array ( 0 => Array ( 0 => Red, 1 => Steel ),
1 => Array ( 0 => Red, 1 => Wood ) ,
2 => Array ( 0 => Blue, 1 => Wood )
);
$a = array_column($arr, 0);print_r($a);