使用另一个数组搜索多维数组的键 [英] Searching multi-dimensional array's keys using a another array

问题描述

是否存在一种优雅的方法来从大型多维数组中获取值，并使用另一个数组作为查找键?

Is there an elegant way of getting values from a massive multi-dimensional array using another array for the keys to lookup?

例如

$cats[A][A1][A11][A111] = $val;
$cats[A][A1][A11][A112] = $val;
$cats[A][A1][A12] = $val;
$cats[A][A1][A12][A121] = $val;
$cats[A][A2] = $val;
$cats[A][A2][A21] = $val;
$cats[A][A2][A22] = $val;
$cats[A][A2][A22][A221] = $val;
$cats[A][A2][A22][A222] = $val;

使用 $ keys = Array('A'，'A2'，'A22'，'A221')从 $ cats 访问值；

access values from $cats using $keys = Array ('A', 'A2', 'A22', 'A221');

无需检查 $ keys 的长度并执行类似的操作...

without checking the length of $keys and doing something like...

switch (count($keys)) {
   case 1: $val = $cats[$keys[0]]; break;
   case 2: $val = $cats[$key[0]][$key[1]]; break;
   case 3: $val = $cats[$key[0]][$key[1]][$key[2]]; break;
   ...
}

非常感谢.

推荐答案

为什么不使用递归?像这样:

Why not use recursion? Something like this:

function get_val($array, $keys) {
    if(empty($keys) || !is_array($keys) || !is_array($array)) return $array;
    else {
        $first_key = array_shift($keys);
        return get_val($array[$first_key], $keys);
    }
}

我本来是将其写成循环的，但是出于某种原因将其更改为递归.确实，正如yeoman所说，递归函数比循环更可能导致堆栈溢出，尤其是在您的数组足够大(PHP确实支持结束递归)的情况下，因此，此循环应达到相同的目的:

I originally had this written in a loop, but changed it to recursive for some reason. It's true, as yeoman said, that a recursive function is more likely than a loop to cause a stack overflow, especially if your array is sufficiently large (PHP does support end recursion), so here's a loop that should accomplish the same purpose:

// given a multidimensional array $array and single-dimensional array of keys $keys
$desired_value = $array;
while(count($keys) > 0) {
    $first_key = array_shift($keys);
    $desired_value = $desired_value[$first_key];
}

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