Question

I have a multidimensional array that looks like this:

$trees = array(
    array(
        'name' => 'Parent',
        '__children' => array(
            array(
                'name' => 'Child'
            ),
            array(
                'name' => 'Second Child'
            )
        )
    )
);

The depth of the array is unknown and I need to recursively flatten it. So it looks more like this:

array(
  array(
    'name' => 'Parent' 
  ),
  array(
    'name' => 'Child' 
  ),
  array(
    'name' => 'Second Child' 
  )
)

I thought something like this might work:

public function flattenTree($trees, $tree = array())
{
    foreach($trees as $item){
        //$i = 1, 2, then 3
        $i = count($tree);
        $tree[$i] = array('name' => $item['name']);
        if(isset($item['__children']))
            $this->flattenTree($item['__children'], $tree);
    }
    return $tree;
}

But this is only gives me 🙁

Array
(
    [0] => Array
        (
            [name] => Parent
        )

)

I am unsure how to do this. Is it possible?

As a bonus I really need the output array to look like this(notice the name value changed) 🙂

array(
  array(
    'name' => 'Parent' 
  ),
  array(
    'name' => 'Parent Child' 
  ),
  array(
    'name' => 'Parent Second Child' 
  )
)

Thanks a ton for the help on this one. Looking forward to the solutions. I am stumped!

Answer 1

I ended up using something like this, with a lot of inspiration from @Pankrates answer. Thanks a lot.

$trees = $multidimensionalArray;
$flat = array();
$postRepository->flattenRecursive($flat, $trees);
//$flat is now a flattened version of $multidimensionalArray
var_dump($flat);


public function flattenRecursive(array &$flat, array $nested, $parentPrepend = false)
{
    foreach( $nested as $item ){
        $flat[] = array(
            'name' => ($parentPrepend) ? $parentPrepend . '/' . $item['name'] : $item['name']
        );
        $prepend = $parentPrepend ? $parentPrepend . '/' . $item['name'] : $item['name'];
        if(isset($item['__children']))
            $this->flattenRecursive($flat, $item['__children'], $prepend);
    }
}