Wordpress Custom Walker，定位第一个和最后一个链接

I have a custom walker set up in Wordpress:

class Custom_Walker_Nav_Menu extends Walker_Nav_Menu {
    function start_el(&$output, $item, $depth = 0, $args = array(), $id = 0) {
        if ( $depth )
            $indent = str_repeat("\t", $depth);
        else
            $indent = '';

        extract($args, EXTR_SKIP);
        $linkName = apply_filters( 'the_title', $item->post_title, $page->ID );
        $output .= $indent . '<li id="item_'.$item->ID.'"><a href="#" class="'.strtolower($linkName).'" data-filter=".'.strtolower($linkName).'">'.$linkName.'</a>';
    }


    function end_el(&$output, $page, $depth = 0, $args = array()) {
        $output .= "</li>
";
    }
}

Which outputs the following:

<nav role="navigation">
    <ul class="simple-nav">
        <li id="item_15"><a href="#" class="home" data-filter=".home">HOME</a></li>
        <li id="item_38"><a href="#" class="directing" data-filter=".directing">DIRECTING</a></li>
        <li id="item_40"><a href="#" class="compositing" data-filter=".compositing">COMPOSITING</a></li>
        <li id="item_42"><a href="#" class="visuals" data-filter=".visuals">VISUALS</a></li>
        <li id="item_74"><a href="#" class="contact" data-filter=".contact">CONTACT</a></li>
    </ul>
</nav>

The data-filter attributes are used by Isotope to filter my results. This works well for the directing, compositing and visuals links.

However for the first link, I would like to attach data-filter=".all" rather than .home

And for the last link, I want this to be an actual link to another page, rather than a blank link #.

How can I add further customisation to these links specifically?

Thanks

for first link try to change,

$output .= $indent . '<li id="item_'.$item->ID.'"><a href="#" class="'.strtolower($linkName).'" data-filter=".'.strtolower($linkName).'">'.$linkName.'</a>';

to

if($item->post_title=='Home')
{
$output .= $indent . '<li id="item_'.$item->ID.'"><a href="#" class="'.strtolower($linkName).'" data-filter=".all">'.$linkName.'</a>';
   }
else
{
$output .= $indent . '<li id="item_'.$item->ID.'"><a href="#" class="'.strtolower($linkName).'" data-filter=".'.strtolower($linkName).'">'.$linkName.'</a>';
}

similarly do the same for last link