使用数组中的递归函数获取一行中的所有数据

I have an array like this

Array
(
    [0] => Array
        (
            [id] => 1
            [category_name] => One
            [parent_id] => 
            [children_recursive] => Array
                (
                )
        )
    [1] => Array
        (
            [id] => 2
            [category_name] => Two
            [parent_id] =>
            [children_recursive] => Array
                (
                )
        )
    [2] => Array
        (
            [id] => 3
            [category_name] => Three
            [parent_id] => 
            [children_recursive] => Array
                (
                    [0] => Array
                        (
                            [id] => 17
                            [category_name] => Three and one
                            [parent_id] => 3
                            [children_recursive] => Array
                                (
                                )
                        )
                    [1] => Array
                        (
                            [id] => 19
                            [category_name] => Three and two
                            [parent_id] => 3
                            [children_recursive] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 21
                                            [category_name] => Three and two and one
                                            [parent_id] => 19
                                            [children_recursive] => Array
                                                (
                                                )
                                        )
                                )
                        )
                    [2] => Array
                        (
                            [id] => 20
                            [category_name] => Three and three
                            [parent_id] => 3
                            [children_recursive] => Array
                                (
                                )
                        )
                )
        )
    [3] => Array
        (
            [id] => 4
            [category_name] => Four
            [parent_id] => 
            [children_recursive] => Array
                (
                    [0] => Array
                        (
                            [id] => 18
                            [category_name] => Four and one
                            [parent_id] => 4
                            [children_recursive] => Array
                                (
                                )
                        )
                )
        )
)

What I want to from this array

One
Two
Three
Three >> Three and one
Three >> Three and two
Three >> Three and two >> Three and two and one
Three >> Three and three
Four
Four >> Four and one

What I have tried

$category = myarray;
renderNode($category);

function renderNode($node) {
        foreach($node as $cat){
            echo $cat['category_name'].'<br >';
            if(!empty($cat[children_recursive'])){
                renderNode($cat[children_recursive']);
            }
        }
    }

And My output is

One
Two
Three
Three and one
Three and two
Three and two and one
Three and three
Four
Four and one

Edit here is the full array list using var_export so you can just copay and paste

array (
  0 => 
  array (
    'id' => 1,
    'category_name' => 'One',
    'parent_id' => NULL,
    'children_recursive' => 
    array (
    ),
  ),
  1 => 
  array (
    'id' => 2,
    'category_name' => 'Two',
    'parent_id' => NULL,
    'children_recursive' => 
    array (
    ),
  ),
  2 => 
  array (
    'id' => 3,
    'category_name' => 'Three',
    'parent_id' => NULL,
    'children_recursive' => 
    array (
      0 => 
      array (
        'id' => 17,
        'category_name' => 'Three and one',
        'parent_id' => 3,
        'children_recursive' => 
        array (
        ),
      ),
      1 => 
      array (
        'id' => 19,
        'category_name' => 'Three and two',
        'parent_id' => 3,
        'children_recursive' => 
        array (
          0 => 
          array (
            'id' => 21,
            'category_name' => 'Three and two and one',
            'parent_id' => 19,
            'children_recursive' => 
            array (
            ),
          ),
        ),
      ),
      2 => 
      array (
        'id' => 20,
        'category_name' => 'Three and three',
        'parent_id' => 3,
        'children_recursive' => 
        array (
        ),
      ),
    ),
  ),
  3 => 
  array (
    'id' => 4,
    'category_name' => 'Four',
    'parent_id' => NULL,
    'children_recursive' => 
    array (
      0 => 
      array (
        'id' => 18,
        'category_name' => 'Four and one',
        'parent_id' => 4,
        'children_recursive' => 
        array (
        ),
      ),
    ),
  ),
)

Something like that:

function getValues($array, $prefix = '')
{
    $values = [];

    foreach ($array as $value) {
        $values[] = $prefix . $value['category_name'];

        if (!empty($value['children_recursive'])) {
            $values = array_merge($values, getValues($value['children_recursive'], $prefix . $value['category_name'] . ' >> '));
        }
    }

    return $values;
}

implode('<br>', getValues($array));

$category = myarray;
renderNode($category);

function renderNode($parent_category_name = '' ,$node) {
        foreach($node as $cat){
            echo $parent_category_name.$cat['category_name'].'<br >';
            if(!empty($cat[children_recursive'])){
                renderNode($parent_category_name .$cat['category_name'] ." >> ", $cat[children_recursive']);
            }
        }
    }

You can use RecursiveArrayIterator. You need to extend it like this:

class RecursiveChildrenIterator extends RecursiveArrayIterator
{
    public function hasChildren()
    {
        return !empty($this->current()['children_recursive']);
    }

    public function getChildren()
    {
        return new static($this->current()['children_recursive']);
    }
}

Having this class you can simply loop with one foreach:

$iterator = new RecursiveIteratorIterator(
    new RecursiveChildrenIterator($array),
    RecursiveIteratorIterator::SELF_FIRST  
);

$result = [];
$current = [];
foreach ($iterator as $item) {
    $current[$iterator->getDepth()] = $item['category_name'];

    if (!$iterator->hasChildren()) {
        $result[] = implode(
            '>>',
            array_slice($current, 0, $iterator->getDepth() + 1)
        );
    }
}

Take a notice on RecursiveIteratorIterator::SELF_FIRST flag passed to RecursiveIteratorIterator.

Here is working demo.

Addition:

I actually misread you desired array, so to get the one you wanted remove the condition:

foreach ($iterator as $item) {
    $current[$iterator->getDepth()] = $item['category_name'];

    $result[] = implode(
        '>>',
        array_slice($current, 0, $iterator->getDepth() + 1)
    );
} 

Here is working demo.

You can read more about iterators.