Walk array recursively and print the path of the walk

Question

Can someone help me with some code or instructions on how to walk recursively an array and when reaching the last element print the full path to it? A simple echo will work

Answer 1

I had similar problem. Here is a Depth-First Search-ish solution(no path depth included, it reaches until the very end of the array). Comment the 'if' statement if u don't want to include the value:

$output = array();
retrievePath($someArray, $output);

function retrievePath($someArray, array &$pathKeeper)
{
    if(!is_array($someArray)){ // $someArray == "end"
        $element = array_pop($pathKeeper) ?? '';// if the array is empty pop returns null, we don't want that
        array_push($pathKeeper, $element . '->'. $someArray);
    } else{
        end($someArray);//we want to get the last element from the array so we move the internal pointer to it's end
        $endElKey = key($someArray);//take the key where the pointer is
        reset($someArray);
        foreach($someArray as $key=>$value){
            $element = array_pop($pathKeeper);
            array_push($pathKeeper, $element === null ? $key : $element . '->' . $key);// we don't want '->' at the beginning
            retrievePath($value, $pathKeeper);
            if($key != $endElKey) //we check whether this is not the last loop
                array_push($pathKeeper, $element);
        }
    }
}

Answer 2

I came up with the following function based on @salathe's one. It returns an array where each element is an array containing the leaf at index 0 and the array of the path keys at index 1:

function loosenMultiDimensionalArrayPathForEachVal($array) {
    $iterator = new \RecursiveIteratorIterator(new \RecursiveArrayIterator($array), \RecursiveIteratorIterator::SELF_FIRST);        
    $iterator->rewind();
    $res = [];
    foreach ($iterator as $v) {
        $depth = $iterator->getDepth();
        for ($path = array(), $i = 0, $z = $depth; $i <= $z; $i++) {
            $path[] = $iterator->getSubIterator($i)->key();
        }
        $leaf = $array;
        foreach ($path as $pathKey) {
            $leaf = $leaf[$pathKey];
        }
        if (!is_array($leaf)) {
            $res[] = [
                $v,
                $path
            ];
        }
    }
    return $res;
}

The main reason I implemented this one is that $iterator->hasChildren() returns true if the current iterated leaf is an object. Therefore, I wouldn't be able to get the path of it that way.

Answer 3

You could employ a RecursiveIteratorIterator (docs) to take the hard work out of recursing through the arrays.

function listArrayRecursive($someArray) {
    $iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($someArray), RecursiveIteratorIterator::SELF_FIRST);
    foreach ($iterator as $k => $v) {
        $indent = str_repeat(' ', 10 * $iterator->getDepth());
        // Not at end: show key only
        if ($iterator->hasChildren()) {
            echo "$indent$k :<br>";
        // At end: show key, value and path
        } else {
            for ($p = array(), $i = 0, $z = $iterator->getDepth(); $i <= $z; $i++) {
                $p[] = $iterator->getSubIterator($i)->key();
            }
            $path = implode(',', $p);
            echo "$indent$k : $v : path -> $path<br>";
        }
    }
}