在多维数组中对值进行分组和求和时未定义索引

Question

我使用以下代码按货币对数组$summary进行分组，并获得分组的持续时间和成本的总和。到目前为止，我可以对数组进行分组和求和，但由于数组单元$result[$split['currency']]['duration']和$result[$split['currency']]['cost']是未定义的，所以当我运行代码时，我会注意到这一点。如何在不使用error_reporting(0)的情况下删除通知？

代码

foreach ($summary as $split) {
            if (isset($split['currency'])) {
                $result[$split['currency']]['duration'] += $split['duration'];
                $result[$split['currency']]['cost'] += $split['cost'];
            } else {
                $result[0]['duration'] += $split['duration'];
                $result[0]['cost'] += $split['cost'];
            }
        }

编辑

$summary = Array
(
[0] => Array
    (
        [currency] => SGD
        [duration] => 8.00
        [cost] => 228.57
    )
[1] => Array
    (
        [currency] => SGD
        [duration] => 8.00
        [cost] => 228.57
    )
[2] => Array
    (
        [currency] => 
        [duration] => 8.00
        [cost] => 
    )
[3] => Array
    (
        [currency] => MYR
        [duration] => 12.00
        [cost] => 342.86
    )
[4] => Array
    (
        [currency] => SGD
        [duration] => 8.00
        [cost] => 228.57
    )
[5] => Array
    (
        [currency] => MYR
        [duration] => 12.00
        [cost] => 342.86
    )

$result如下所示

 Array
(
[0] => Array
    (
        [currency] => SGD
        [duration] => 24
        [cost] => 685.71
    )
[1] => Array
    (
        [currency] => MYR
        [duration] => 24
        [cost] => 685.72
    )
[2] => Array
    (
        [currency] => 
        [duration] => 8
        [cost] => 0
    )

)

Answer 1

您需要首先定义数组：

foreach ($summary as $split) {
        if (isset($split['currency'])) {
            if (!isset($result[$split['currency']]) {
                $result[$split['currency']] = [
                    'duration' => 0,
                    'cost' => 0
                ];
            }
            $result[$split['currency']]['duration'] += $split['duration'];
            $result[$split['currency']]['cost'] += $split['cost'];
        } else {
            $result[0]['duration'] += $split['duration'];
            $result[0]['cost'] += $split['cost'];
        }
    }

Answer 2

还测试$result数组索引的存在性。

foreach ($summary as $split) {
    if (isset($split['currency'])) {
        if(!isset($result[$split['currency']])) {
        $result[$split['currency']]['duration'] = $split['duration'];
        $result[$split['currency']]['cost'] = $split['cost'];  
        } else {
        $result[$split['currency']]['duration'] += $split['duration'];
        $result[$split['currency']]['cost'] += $split['cost'];
        }
    } else {
        $result[0]['duration'] += $split['duration'];
        $result[0]['cost'] += $split['cost'];
    }
}

Answer 3

我不明白是否需要额外的条件块。

使用currency作为临时密钥。在第一次遇到currency时，存储整行。否则，将当前迭代的duration和cost添加到存储的组中。循环结束后，使用array_values()重新索引数组。

代码：（演示）

$result = [];
foreach ($array as $row) {
    if (!isset($result[$row['currency']])) {
        $result[$row['currency']] = $row;
    } else {
        $result[$row['currency']]['duration'] += $row['duration'];
        $result[$row['currency']]['cost'] += $row['cost'];
    }
}
var_export(array_values($result));

输出：

array (
  0 => 
  array (
    'currency' => 'SGD',
    'duration' => 16.0,
    'cost' => 457.14,
  ),
  1 => 
  array (
    'currency' => NULL,
    'duration' => 8.0,
    'cost' => NULL,
  ),
  2 => 
  array (
    'currency' => 'MYR',
    'duration' => 24.0,
    'cost' => 685.72,
  ),
)