Converting a One-Dimensional Array into a Nested Array Using Relationship Keys - php

Question

Say I have an array with keys representing id and values representing parent:
4 => 0
2 => 0
5 => 2
6 => 5
8 => 0
9 => 0
10 => 8
12 => 0
13 => 0
14 => 0
18 => 7
19 => 18
20 => 19
21 => 20
22 => 21
23 => 22
24 => 23
28 => 20
7 => 5
You could also read this as an object:
{
id : 4,
parent : 0
} // etc...
The multidimensional array I'd want to achieve from this would be:
4 => 0
2 => 5
=> 6
=> 7
=> 18
=> 19
=> 20
=> 21
=> 22
=> 23
=> 24
=> 28
8 => 10
9 => 0
12 => 0
13 => 0
14 => 0
How would I go about doing this?

Answer 1

If you write a little helper function to rework your data to a structure similar to:
$input = array(
array('id' => '4', 'parent' => '0'),
// ...
);
which could be achieved with something like:
$data = array_map(function ($entry) {
list($id, $parent) = array_map('trim', explode('=>', $entry));
return array(
'id' => $id,
'parent' => $parent
);
}, explode("\n", $data));
you could then use a function I used in a similar question:
function flatToNested($d, $r = 0, $p = 'parent', $k = 'id', $c = 'children') {
$m = array();
foreach ($d as $e) {
isset($m[$e[$p]]) ?: $m[$e[$p]] = array();
isset($m[$e[$k]]) ?: $m[$e[$k]] = array();
$m[$e[$p]][] = array_merge($e, array($c => &$m[$e[$k]]));
}
return $m[$r];
}
to produce a nested array with:
$nested = flatToNested($data);
demo: http://codepad.viper-7.com/HAZxaA