PHP让数组中有相同值的组成新的数组实例

实例如下所示：

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$arr = array(   0=>array('key1'=>'value1' , 'key2'=>'value2'),   1=>array('key1'=>'value1' , 'key2'=>'value3'),   2=>array('key1'=>'value2' , 'key2'=>'value4'),   999=>array('key1'=>'value2' , 'key2'=>'value5') );    $result = array(); <span style="color:#FF0000;">foreach ($arr as $data) {   isset($result[$data['key1']]) || $result[$data['key1']] = array();   $result[$data['key1']][] = $data['key2']; }span> ksort($cityAr, SORT_NATURAL);//这个是键值按字母先后顺序排列 print_r($result);    //输出如下 Array (   [value1] => Array     (       [0] => value2       [1] => value3     )      [value2] => Array     (       [0] => value4       [1] => value5     )        )