什么是在PHP中生成这种压缩数组的最佳方式？

Question

我有一个数组，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"); 

从这我需要生成的稠阵列等

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

基本上，第一个是一个多维阵列中，包含日期，id和量。在新数组中，我需要将每个唯一日期的前一个压缩，将重复日期的csv作为csv字符串，并添加数量。

什么是最有效的方式来做到这一点，性能明智吗？

Answer 1

像这样的东西应该这样做：

$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