rearrange a php array into a nested hierarchical array

Question

How can I transform array#1 into the array#2 structure using php ?

The first Array is the results of a database query on a list of Organisms, each organism is classified

Answer 1

I don't think this will be super-efficient for really large arrays, but it works for your scenario (here's a sample).

 $array = ...
 $levels = array('Rank_Order', 'Rank_Family', 'Rank_Genus', 'Rank_Species');

 function get_children($parent, $lev, $orig, $levels){
     if($lev + 1 > count($levels)){
          return array();
     }

     $seen = array();
     $children = array();
     foreach($orig as $node){
         if($node[$levels[$lev]] == $parent && !in_array($node[$levels[$lev+1]], $seen)){
             $seen[] = $node[$levels[$lev+1]];
             $children[] = get_children($node[$levels[$lev+1]], $lev+1, $orig, $levels);
         }
     }
     return array('name' => $parent, 'children' => $children);
 }

 function hier($orig, $levels){
     $seen = array();
     $result = array();
     foreach($orig as $node){
         if(!in_array($node[$levels[0]], $seen)){
              $seen[] = $node[$levels[0]];
              $result[] = get_children($node[$levels[0]], 0, $orig, $levels);
         }
     }
     return $result;
 }

 print_r($array);
 print_r(hier($array, $levels));