PHP 配列の基礎プログラミング

<?php
 
 $events[] = array('Time' => 1000, 'Area' => 360);
 $events[] = array('Time' => 100, 'Area' => 100);
 $events[] = array('Time' => 100, 'Area' => 100);
 $events[] = array('Time' => 100, 'Area' => 100);
 
 $sum_datas = array();
 
 foreach ($events as $event) {
         $area = (string) $event['Area'];
         if (empty($sum_data["$area"])) {$sum_data["$area"] = 0;}
         $sum_datas["$area"] += $event['Time'];
 }       
 
 $output_data = array();
 foreach ($sum_datas as $key => $value) {
         $output_data[] = array('y' => $key, 'time' => $value);
 }
 
 var_dump($output_data);