php二維數組處理

$arr=array(    array('amount'=>100,'date'=>'2014-03-29'),    array('amount'=>120,'date'=>'2014-03-30'),    array('amount'=>200,'date'=>'2014-03-31'));

怎麼轉化成以日期為準，amount為之前amount的和？

$arr=array(    array('amount'=>100,'date'=>'2014-03-29'),    array('amount'=>220,'date'=>'2014-03-30'),    array('amount'=>420,'date'=>'2014-03-31'));

回複內容：

$arr=array(    array('amount'=>100,'date'=>'2014-03-29'),    array('amount'=>120,'date'=>'2014-03-30'),    array('amount'=>200,'date'=>'2014-03-31'));

怎麼轉化成以日期為準，amount為之前amount的和？

$arr=array(    array('amount'=>100,'date'=>'2014-03-29'),    array('amount'=>220,'date'=>'2014-03-30'),    array('amount'=>420,'date'=>'2014-03-31'));

function sd($a,$b) {if($a['date'] == $b['date']) return 0; return $a['date'] >$b['date'] ? 1 : -1;usort($arr, 'sd');$amount = 0;foreach($arr as &$item) {    $amount += $item['amount'];    $item['amount'] = $amount;}

    $originArr=array(        array('amount'=>100,'date'=>'2014-03-29'),        array('amount'=>120,'date'=>'2014-03-30'),        array('amount'=>200,'date'=>'2014-03-31')    );    $newArr1 = array();    $newArr2 = array();    $tempArr = array();    $resultArr = array();    foreach($originArr as $el) {        $newArr1[$el['date']] = $el['amount'];    }    foreach ($newArr1 as $k1 => $v1) {        foreach ($newArr1 as $k2 => $v2) {            $v1 += ($k1 > $k2) ? $v2 : 0;        }        $newArr2[$k1] = $v1;     }     foreach($newArr2 as $key => $value) {        $tempArr['amount'] = $value;        $tempArr['date'] = $key;        $resultArr[] = $tempArr;     }

100,'date'=>'2014-03-29'),    array('amount'=>200,'date'=>'2014-03-31'),        array('amount'=>120,'date'=>'2014-03-30'),);$total = 0;//以日期遞增排序uasort($arr, function($a, $b) {    return strtotime($a['date']) - strtotime($b['date']);});array_walk_recursive($arr, function(&$val, $key) use (&$total) {    if ($key === 'amount') {        $total +=  $val;        $val = $total;    }});print_r($arr);

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