在PHP多维数组中返回其父节点的所有节点值

Question

I have a simple multidimensional array like this: `

$array= [
    'A' => [
        'B' => ['D', 'E', 'F'],
    'C' => 'G',
    ],
];

I need to return all node values with their parents. So I need an output like:

P[A] = 0;
P[B] = A;
P[D] = B;
P[E] = B;
P[F] = B;
P[C] = A;
P[G] = C;

I've tried some functions like array_search() , array_walk_recursive and so on, but I couldn't apply these functions to my situation. Thanks very much for any help!

Answer 1

function recursive($arr, $parentKey, &$flattened) {
    foreach ($arr as $key => $item) {
        if (is_array($item)) {
            recursive($item, $key, $flattened);
            $flattened[$key] = $parentKey;
        } else {
            if (is_numeric($key)) {
                $flattened[$item] = $parentKey;
            } else {
                $flattened[$item] = $key;
                $flattened[$key] = $parentKey;
            }
        }
    }
}

$inputArray= [
    'A' => [
        'B' => ['D', 'E', 'F'],
        'C' => 'G'
    ]
];

$result = [];
recursive($inputArray, 0, $result);
var_dump($result); // array(7) { ["D"]=> string(1) "B" ["E"]=> string(1) "B" ["F"]=> string(1) "B" ["B"]=> string(1) "A" ["G"]=> string(1) "C" ["C"]=> string(1) "A" ["A"]=> int(0) } 

Answer 2

You could do this with an recursive function, that has the "parent" as optional second parameter.

$array = [
    'A' => [
        'B' => [ 'D', 'E', 'F' ],
        'C' => 'G',
    ],
];

function showParents($arr, $parent = 0) {
    foreach($arr as $key => $val) {
        if(is_array($val)) {
            // for when the element is an array
            echo '[' . $key . '] ' . $parent . '<br>';
        } else if(is_int($key)){
            // for when the array is an not-associative one (or are you using INTs as keys also?)
            echo '[' . $val . '] ' . $parent . '<br>';
        } else if(is_string($val)){
            // for when the value is a string ('C' => 'G')
            echo '[' . $key . '] ' . $parent . '<br>';// display parent of C
            echo '[' . $val . '] ' . $key . '<br>';// display parent of G
        }

        if(is_array($val)) {
            // when the current value is an array, go deeper
            showParents($val, $key);
        }
    }
}

showParents($array);

Displays:

[A] 0
[B] A
[D] B
[E] B
[F] B
[C] A
[G] C