Resolve a multi dimensional array into fully specified endpoints

I need to turn each end-point in a multi-dimensional array (of any dimension) into a row containing the all the descendant nodes using PHP. In other words, I want to resolve each complete branch in the array. I am not sure how to state this more clearly, so maybe the best way is to give an example.

If I start with an array like:

$arr = array(
 'A'=>array(
    'a'=>array(
        'i'=>1, 
        'j'=>2),
    'b'=>3
 ),
 'B'=>array(
    'a'=>array(
        'm'=>4, 
        'n'=>5),
    'b'=>6
 )
);

There are 6 end points, namely the numbers 1 to 6, in the array and I would like to generate the 6 rows as:

1. A,a,i,1
2. A,a,j,2
3. A,b,2
4. B,a,m,3
5. B,a,n,4
6. B,b,2

Each row contains full path of descendants to the end-point. As the array can have any number of dimensions, this suggested a recursive PHP function and I tried:

function array2Rows($arr, $str='', $out='') {
  if (is_array($arr)) {
    foreach ($arr as $att => $arr1) {
        $str .= ((strlen($str)? ',': '')) . $att;
        $out = array2Rows($arr1, $str, $out);
    }
    echo '<hr />';
  } else {
    $str .= ((strlen($str)? ',': '')) . $arr;
    $out .= ((strlen($out)? '<br />': '')) . $str;
  }
  return $out;
}

The function was called as follows:

echo '<p>'.array2Rows($arr, '', '').'</p>';

The output from this function is:

1. A,a,i,1
2. A,a,i,j,2
3. A,a,b,3
4. A,B,a,m,4
5. A,B,a,m,n,5
6. A,B,a,b,6

Which apart from the first value is incorrect because values on some of the nodes are repeated. I have tried a number of variations of the recursive function and this is the closest I can get.

I will welcome any suggestions for how I can get a solution to this problem and apologize if the statement of the problem is not very clear.

source https://stackoverflow.com/questions/70147772/resolve-a-multi-dimensional-array-into-fully-specified-endpoints