$re = '/((?:max|min)\s\(\s*\d+(?:\s*,\s*\d+)*\s*\))|(?:,\d+)+/m';
$str = 'max ( 100,200,30,4 )
min ( 10,23,111 )
min ( 10,20 )
10,2,34 + 4';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php