多维数组中的元素总和

Question

我有以下输入：

$data = array(
    0 => array(
        'date' => '2014-01-01',
        'sales' => 1,
        'price' => array(
            'usd' => 1,
            'eur' => 100
        )
    ),
    1 => array(
        'date' => '2014-01-05',
        'sales' => 1,
        'price' => array(
            'usd' => 1,
            'eur' => 100,
            'gbp' => 500
        )
    ),
    2 => array(
        'date' => '2016-03-27',
        'sales' => 5,
        'age' => 50
    ),
    3 => array( 
        'date' => '2016-03-28',
        'sales' => 10
    )
);

我期待以下输出：

$final = array(
    'March 2016' => array(
        'sales' => 15
    ),
    'January 2014' => array(
        'sales' => 2,
        'price' => array(
            'usd' => 2,
            'eur' => 200,
            'gbp' => 500
        )
    )
);

到目前为止我做了什么？

$monthlyData = array();

foreach ($dailyData as $day)
{
    $key = date('M y', strtotime($day['date']));

    if (!isset($monthlyData[$key]))
    {
        $monthlyData[$key] = $day;
        continue;
    }

    foreach ($day as $metric => $value)
    {
        if(!empty($value)) 
        {
            $monthlyData[$key][$metric] += $value;
        }
    }
}

嗯，我知道我们可以使用好的'foreach（使用递归调用）来获得正确的结果，但我正在寻找一些更优雅的解决方案。