Add elements to an array inside a foreach loop

I have the code below:

<?php

$i = array(1, 2, 3);

$w = array(1 => '11', 2 => '22', 3 => '33');

foreach ($i as $f) {
    $ws = $w[$f];

    $file_names[] = array(
        'fn' => 'fname',
        'sn' => 'sname',
        'is' => 'is',
        'rv' => 'rv'
    );

    foreach ($file_names as $k => $v) {
        if (!isset($file_names[$k]['mod'])) {
            $file_names[$k]['mod'] = array(
                'ct',
                'pt'
            );
        }

        if (!isset($file_names[$k]['pw'])) {
            $file_names[$k]['pw'] = array(
                'task'  => '3',
                'min'   => 'min',
                'max'   => 'max',
                'value' => "" . $ws . ""
            );
        }
    }
}

print_r($file_names);

?>

What I’m trying to do is add new elements to an array in some particular conditions. The only thing that I don’t like is the second foreach loop part. I.e.:

    foreach ($file_names as $k => $v) {
        if (!isset($file_names[$k]['mod'])) {
            $file_names[$k]['mod'] = array(
                'ct',
                'pt'
            );
        }

        if (!isset($file_names[$k]['pw'])) {
            $file_names[$k]['pw'] = array(
                'task'  => '3',
                'min'   => 'min',
                'max'   => 'max',
                'value' => "" . $ws . ""
            );
        }
    }

Is there any way to write this in a more elegant manner?