[WordPress] カテゴリーを階層の深い順に並び替える

gistfile1.php

<?php
// Get categories of current post
$_cats = get_the_terms( get_post(), 'category');

$_sort = array();
$cats = array();

// Get the depth of each categories
foreach( $_cats as $_cat ) {
	$depth = count( get_ancestors( $_cat->term_id, 'category' ) );
	$_sort[$_cat->term_id] = $depth;
}

// Sort by depth
arsort($_sort);

// Build sorted array of categories
foreach( $_sort as $id => $depth ) {
	$cats[$id] = $_cats[$id];
}

unset($_cats);
unset($_sort);

// done!
var_dump($cats);