PHP二维数组的表格输出

<?php

$arr1 = array(
"nokia" => array('lumia800','lumia900','lumia1520'),
"apple" => array('iphone4s','iphone5c','iphone6s'),
"msoft" => array('surface1','surface2','surface3')
);

$arr2 = array(
array('lumia800','lumia900','lumia1520'),
array('iphone4s','iphone5c','iphone6s'),
array('surface1','surface2','surface3')
);

echo "<table border='1px'>";
foreach($arr2 as $key=>$val){
echo "<tr>";
foreach($val as $detail){
echo "<td>".$detail."</td>";
}
echo "</tr>";
}
echo "</table>";
?>