need help understanding taxonomy term sorting behavior, and how to override

…just what I've basically been looking for - thank you very much for this thread - and this handy code! …although I must say that I somehow actually had strange problems with the return/explode line - and I don't know why. Additionally I wasn't 100% happy with the line "$node = node_load(arg(1));" - so I changed that to "$node_id = ($node->nid);". And then I anyways needed the hierarchical terms more separately - additionally I needed the related term-IDs to compare with the curent URL so that I can hide and/or style the 'active' term - and since I only have three 'levels' I did the following:

// alternative snippet for separate term variables

$vid = 1; // Taxonomy ID for my Geo-Tags

$treeterms = taxonomy_get_tree($vid, 0, 0); // Gets list of ALL taxonomy terms in tree order

// $node = node_load(arg(1)); // didn't work for me - confusion with '$node' - and is not really needed anyways..

$nodeterms = taxonomy_node_get_terms_by_vocabulary($node->nid, $vid); // Gets taxonomy terms assigned to the current node only.

$node_term_cmp = create_function('$term_1,$term_2', 'return $term_1->tid - $term_2->tid;'); // Callback function for uinstersect.

$iterms = array_uintersect($treeterms, $nodeterms, $node_term_cmp); // Matches terms between the two lists, keeping the tree order.

// build the arrays - although this also seems not really necessary - or is it?
$links = array();
$termid = array();

// loading info into the arrays
foreach($iterms as $iterm) {
   $links[] = l($iterm->name, taxonomy_term_path($iterm)); // gets the term with appropriate link
   $termid[] = check_plain($iterm->tid, taxonomy_term_path($iterm)); // gets the TID (without link)
  }

$country = $links[0];
$city = $links[1];
$hood = $links[2];

$country_tid = $termid[0];
$city_tid = $termid[1];
$hood_tid = $termid[2];

with this info I can do something like this:

echo("geo-tags: ");

if($country_tid == arg(2)) {
echo("Country: <b>".$country."</b> ");
} 

if($city_tid == arg(2)) {
echo("Country: ".$country.", City: <b>".$city."</b> ");
} 

if($hood_tid == arg(2)) {
echo("Country: ".$country.", City: ".$city.", Neighbourhood: <b>".$hood."</b> ");
} 

…I use this on taxonomy pages - or actually on a panels page that overwrites a taxonomy page and therefore I get the term ID from arg(2)…

…greetz, t..

Excellent - thanks just what i needed.

I modified it since I needed it to display my taxonomy like the awesome Hierarchical Select module does - ex:
Canada, Nova Scotia
United States of America, Arizona, Phoenix

So my mod the terms are listed with each set (parent and children) on a separate line and NOT as links. Making them links is just a matter of reinserting the code from above.

PS: I put the snippet in a contemplate where it seemed to like "print" command versus "return"

    <?php
    // PHP snippet to print taxonomy terms in proper tree order with no links and each "set" on separate lines
    // See http://drupal.org/node/249010#comment-839993 for initial source code
    $key_vid = 18; // Desired taxonomy vid
    $treeterms = taxonomy_get_tree($key_vid, 0, 0); // Gets list of ALL of the vocabulary terms in tree order
    $node = node_load(arg(1)); // Gets the number of the current node.
    $nodeterms = taxonomy_node_get_terms_by_vocabulary($node->nid, $key_vid); // Gets terms assigned to the current node only.
    $node_term_cmp = create_function('$term_1,$term_2', 'return $term_1->tid - $term_2->tid;'); // Callback function for uinstersect.
    $iterms = array_values(array_uintersect($treeterms, $nodeterms, $node_term_cmp)); // Matches terms between the two lists, keeping the tree order and reindexes with array_values
    $total_terms = (count($iterms));
    $names = $iterms[0]->name;
    $tid_old = $iterms[0]->tid;
    for ($i=1; $i <= $total_terms; $i++ ) {
      if ($iterms[$i]->parents[0] == $tid_old) {
          $names .= ", ";
      } else {
         $names .= "<br>" ;
      }
    $names .= $iterms[$i]->name;
    $tid_old = $iterms[$i]->tid;
    }
    print $names;
    ?>