php抓取这个网页的数据，只要数据，不用html内容，然后json后写入文件，新手求教

$url = 'http://www.okooo.com/Upload/sohu/table_23.html';
$s = file_get_contents($url);
preg_match_all('##isU', $s, $m);
foreach(array_map('strip_tags', $m[0]) as $r) {
  $a = preg_split('/\s+/', $r, -1, PREG_SPLIT_NO_EMPTY);
  $res[] = array_chunk(array_slice($a, 0, -1), 3);
}
print_r($res);
echo json_encode($res);

Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [0] => 排名
                    [1] => 球队
                    [2] => 积分
                )

            [1] => Array
                (
                    [0] => 1
                    [1] => 尤文图斯
                    [2] => 102
                )

            [2] => Array
                (
                    [0] => 2
                    [1] => 罗马
                    [2] => 85
                )

            [3] => Array
                (
                    [0] => 3
                    [1] => 那不勒斯
                    [2] => 78
                )

            [4] => Array
                (
                    [0] => 4
                    [1] => 佛罗伦萨
                    [2] => 65
                )

            [5] => Array
                (
                    [0] => 5
                    [1] => 国际米兰
                    [2] => 60
                )

            [6] => Array
                (
                    [0] => 6
                    [1] => 帕尔马
                    [2] => 58