<?php
$arr = array(
    'a' => array(
        'a' => 'apple',
        'b' => 'banana',
        'c' => 'cranberry',
        'd' => 'mango',
        'e' => 'pineapple'
    ),
    'b' => array(
        'a' => 'apple',
        'b' => 'banana',
        'c' => 'cranberry',
        'd' => 'mango',
        'e' => 'pineapple'
    ),
    'c' => 'cranberry',
    'd' => 'mango',
    'e' => 'pineapple'
);

function test(&$child, $entry)
{
    $i = 1;

    foreach ($child AS $key => $fruit)
    {
        if (!is_numeric($key))
        {
            $child[$i] = $fruit;
            unset($child[$key]);
            $i++;
        }
    }
}

$i = 1;

foreach ($arr AS $key => $fruit)
{
    $arr[$i] = $fruit;

    if (is_array($fruit))
    {
        test($arr[$i], $fruit);
    }

    unset($arr[$key]);
    $i++;
}

var_dump($arr);
?>