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<?php $originArr=array( array('amount'=>100,'date'=>'2014-03-29'), array('amount'=>120,'date'=>'2014-03-30'), array('amount'=>200,'date'=>'2014-03-31'), array('amount'=>300,'date'=>'2014-04-31'), array('amount'=>400,'date'=>'2014-05-31') ); $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[] = $tempArr; } var_dump($resultArr);

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