ordering by heirarchy

[chloe]

Hi there!

I've been going crazy trying to figure out how to solve this problem. It's really got me stumped :mad:

Essentially i want to take this sort of array:

[0] => Array
		(
				[id] => 1
				[parent] => 0
				[title] => Food
		)

[1] => Array
		(
				[id] => 2
				[parent] => 1
				[title] => Fruit
		)

[2] => Array
		(
				[id] => 3
				[parent] => 1
				[title] => Vegetables
		)

[3] => Array
		(
				[id] => 4
				[parent] => 2
				[title] => Oranges
		)

[4] => Array
		(
				[id] => 5
				[parent] => 2
				[title] => Apples
		)

And order it like so:

[0] => Array
		(
				[id] => 1
				[parent] => 0
				[title] => Food
		)

[1] => Array
		(
				[id] => 2
				[parent] => 1
				[title] => Fruit
		)

[2] => Array
		(
				[id] => 4
				[parent] => 2
				[title] => Oranges
		)

[3] => Array
		(
				[id] => 5
				[parent] => 2
				[title] => Apples
		)

[4] => Array
		(
				[id] => 3
				[parent] => 1
				[title] => Vegetables
		)

Notice how i'm trying to order it as if reading a tree diagram from top to bottom.

The only indication of depth I have is the "parent" field and there could be an unlimited depth of children.

Really appreciate any time anyone spends on this.

[mrhappiness]

recursion is such a funny thing

//create array
$array[] = array('id' => 1, 'parent' => 0, 'title' => 'Food');
$array[] = array('id' => 2, 'parent' => 1, 'title' => 'Fruit');
$array[] = array('id' => 3, 'parent' => 1, 'title' => 'Vegetables');
$array[] = array('id' => 4, 'parent' => 2, 'title' => 'Oranges');
$array[] = array('id' => 5, 'parent' => 2, 'title' => 'Apples');

function do_sort($array, &$result, $parent = 0) {
    //count number of elements
    $count = count($array);
    for ($i = 0; $i < $count; $i++)
        if ($array[$i]['parent'] == $parent) {
        //current element belongs to given parent
            $result[] = $array[$i];
        //recursion: look for elements belonging to current element
            do_sort($array, $result, $array[$i]['id']);
        }
}

do_sort($array, $array_new);
echo '<pre>';
print_r($array);
print_r($array_new);
echo '</pre>'; 

[chloe]

You sir, are one amazing individual.

Thank you very, very much - i think i'm actually beginning to comprehend it too 😉