Related maps in PLOTS website (drupal)

related_maps.php

<ul><?php

$distance = 0.1;
$node = node_load(arg(1));

$sw = geo_value($node->field_bbox[0]['wkb'], 'array','wkb');
$ne = geo_value($node->field_bbox[1]['wkb'], 'array','wkb');

$sql = "SELECT DISTINCT(n.nid) FROM {node} n WHERE n.status=1 AND n.type='map'";

$result = db_query($sql);

$nodes = array();

while ($row = db_fetch_array($result) ) {
  $n = node_load($row["nid"]);
  $element = $n->field_bbox;
  $nsw = geo_value($element[0]['wkb'], 'array','wkb');
  $nne = geo_value($element[1]['wkb'], 'array','wkb');

  if (abs($sw[lon] - $nsw[lon]) < $distance && abs($sw[lat] - $nsw[lat]) < $distance && $n->nid != $node->nid) { // if it's within 1/10 a degree, add it
      $nodes[] = $n;
?>
<li><a href="/<?php echo $n->path; ?>"><?php echo $n->title; ?></a> 
(<?php echo date("F j, Y",strtotime($n->field_capture_date[0][value])); ?>)</li>

<?php }} ?></ul>
<?php if (sizeof($nodes) == 0) { echo "<p>None nearby.</p>"; } ?>