<?php

	function replace_num ($num) {
		$a = array (1 => 'I', 2 => 'II', 3 => 'III', 4 => 'IV', 5 => 'V', 6 => 'VI', 7 => 'VII', 8 => 'VIII', 9 => 'IX');
		$b = array();
		foreach (explode(',', $num) as $c) $b[] = $a[$c];
		return implode(',', $b);
	}

	echo replace_num('1,2,3,4,5,6,7,8,9');

?>