什麼是在PHP中生成這種壓縮數組的最佳方式？

Question

我有一個數組，如：

$arr[0] = ("1-3-2011","1","15"); //date(dd-mm-yyyy),id,amt 
$arr[1] = ("1-4-2011","2","5"); 
$arr[2] = ("12-3-2011","6","20"); 
$arr[3] = ("1-3-2011","10","10"); 
$arr[4] = ("12-3-2011","3","10"); 
$arr[5] = ("1-4-2011","5","15"); 
$arr[6] = ("1-3-2011","7","15"); 

從這我需要生成的稠陣列等

$newarr[0] = ("1-3-2011","1,7,10","40"); 
$newarr[0] = ("1-4-2011","2,5","20"); 
.. 
... 

基本上，第一個是一個多維陣列中，包含日期，id和量。在新數組中，我需要將每個唯一日期的前一個壓縮，將重複日期的csv作爲csv字符串，並添加數量。

什麼是最有效的方式來做到這一點，性能明智嗎？

Answer 1

像這樣的東西應該這樣做：

$newarr = array(); 

foreach($arr as $row) { 
    if(!isset($newarr[$row[0]])) { 
     $newarr[$row[0]] = array('ids' => array(), 'amount' => 0); 
    } 
    $newarr[$row[0]]['ids'][] = $row[1]; 
    $newarr[$row[0]]['amount'] += $row[2]; 
} 

foreach($newarr as $key => &$row) { 
    $row = array($key, implode(',', $row['ids']), $row['amount']); 
} unset($row); 

工作例如：

http://codepad.org/UmiDKLYJ