I have an array like so:

array(
    'a'=>array(
        'a'=>3,
        'f'=>5,
        'sdf'=>0),
    't'=>array(
        'a'=>1,
        'f'=>2,
        'sdf'=>5),
    'pps'=>array(
        'a'=>1,
        'f'=>2,
        'sdf'=>3)
);

Notice how the sub-arrays are the same for each top-level array. If I wanted to, what's the easiest way to combine the sub-arrays so that I'm left with a one-dimensional array like:

array(
    'a'=>5,
    'f'=>9,
    'sdf'=>8
);