Sorting infinite depth array - php - php

Question

I have the following array: (ordered by parent_id)
array(9) {
[1]=>
array(3) {
["name"]=>
string(6) "Tennis"
["parent_id"]=>
NULL
["depth"]=>
int(0)
}
[7]=>
array(3) {
["name"]=>
string(11) "TOP LEVEL 2"
["parent_id"]=>
NULL
["depth"]=>
int(0)
}
[8]=>
array(3) {
["name"]=>
string(11) "TOP LEVEL 3"
["parent_id"]=>
NULL
["depth"]=>
int(0)
}
[2]=>
array(3) {
["name"]=>
string(5) "Shoes"
["parent_id"]=>
string(1) "1"
["depth"]=>
int(1)
}
[3]=>
array(3) {
["name"]=>
string(5) "Women"
["parent_id"]=>
string(1) "2"
["depth"]=>
int(2)
}
[4]=>
array(3) {
["name"]=>
string(4) "Mens"
["parent_id"]=>
string(1) "2"
["depth"]=>
int(2)
}
[5]=>
array(3) {
["name"]=>
string(12) "Mens Running"
["parent_id"]=>
string(1) "4"
["depth"]=>
int(3)
}
[6]=>
array(3) {
["name"]=>
string(11) "Mens Tennis"
["parent_id"]=>
string(1) "4"
["depth"]=>
int(3)
}
[9]=>
array(3) {
["name"]=>
string(9) "2nd level"
["parent_id"]=>
string(1) "8"
["depth"]=>
int(1)
}
}
I want to sort it in a way that it can be used in a drop down menu. The format for a drop down menu is:
$categories[$CATEGORY_ID] = str_repeat(' ', $value['depth']).$value['name'];
The above array up top is sorted by parent_id where top levels have a parent_id of NULL.
I need to sort it in such a way that the array is in order. For example:
[1] => 'Tennis';
[2] => ' &nbspShoes'
[3] => ' Womens'
[4] => ' Men'
[5] => ' Mens Running
[6] => ' Mens Tennis
[7] => 'TOP LEVEL 2'
[8] => 'TOP LEVEL 3'
[9] => ' 2nd level'
I tried this:
function get_all_categories_and_subcategories($parent_id = NULL, $depth = 0)
{
$categories = $this->get_all($parent_id, 10000, 0, 'parent_id');
if (!empty($categories))
{
$unique_parent_ids = array();
foreach($categories as $id => $value)
{
$categories[$id]['depth'] = $depth;
$unique_parent_ids[$id] = TRUE;
}
foreach(array_keys($unique_parent_ids) as $id)
{
$categories = array_replace($categories, $this->get_all_categories_and_subcategories($id, $depth + 1));
}
return $categories;
}
else
{
return $categories;
}
}
function sort_categories($categories)
{
usort($categories, array('Category','do_sort_categories'));
return $categories;
}
static function do_sort_categories($a, $b)
{
$al = strtolower($a['parent_id']);
$bl = strtolower($b['parent_id']);
if ($al == $bl) {
return 0;
}
return ($al > $bl) ? +1 : -1;
}
function get_all($parent_id = NULL, $limit=10000, $offset=0,$col='name',$order='asc')
{
$this->db->from('categories');
if (!$this->config->item('speed_up_search_queries'))
{
$this->db->order_by($col, $order);
}
if ($parent_id === NULL)
{
$this->db->where('parent_id IS NULL', null, false);
}
else if($parent_id)
{
$this->db->where('parent_id', $parent_id);
}
$this->db->limit($limit);
$this->db->offset($offset);
$return = array();
foreach($this->db->get()->result_array() as $result)
{
$return[$result['id']] = array('name' => $result['name'], 'parent_id' => $result['parent_id']);
}
return $return;
}

Answer 1

I don't have the possibility to test this code right now, but you could try something like this (and correct from my comments if needed).
Hope it would help a bit.
$objects = array();
// turn to array of objects to make sure our elements are passed by reference
foreach ($array as $k => $v) {
$node = new StdClass();
$node->id = $k;
$node->parent_id = $v['parent_id'];
$node->name = $v['name'];
$node->depth = $v['depth'];
$node->children = [];
$objects[$k] = $node;
}
// list dependencies parent -> children
foreach ($objects as $node)
{
$parent_id = $node->parent_id;
if ($parent_id !== null)
{
$object[$parent_id][] = $node;
}
}
// sort children of each node
foreach ($objects as $node)
{
usort($node->children, function($a, $b){
return $a->id < $b->id;
});
}
// clean the object list to make kind of a tree (we keep only root elements)
$sorted = array_filter($objects, function($node){
return $node->depth === 0;
});
// flatten recursively
function flatten_node(&$node) {
return array_merge([$node], flatten($node->children));
}
array_walk($sorted, 'flatten_node');
// $sorted is a sorted list of objects (not array as defined at the beginning).
// You could turn it back to array and remove the 'children' key that was
// only used for sorting purposes.