php - "vertical"数组子元素总和的 native 函数，如 vertical_sum($array[$day_of_year] ["income"]);

Question

标题说明了一切:在 php 中是否有一个垂直求和函数，它在整个数组上添加一个(子)数组值，如下所示:

 // pseudo code that would return the sum of "income" for all days of the year
 // for example
 vertical_sum($array[$day_of_year]["income"]);

Answer 1

原生函数？不完全是，但数组缩减可以提供帮助:

$array = array(
    array('income' => 1), //day 1
    array('income' => 3), //day 2, etc
    array('income' => 6),
    array('income' => 7)
);
echo array_reduce($array, function($curr_total, $this_val) {
    return $curr_total + $this_val['income'];
}, 0); //17