Creating a Multi-Dimentional from another Multi Dimensional Array - php

Question

Wrecking my brains for a while now and need your help
I have an array as below:
$originalArray = array(
array('id' => 1, 'sub-id' => 0),
array('id' => 2, 'sub-id' => 0),
array('id' => 3, 'sub-id' => 1),
array('id' => 4, 'sub-id' => 3),
array('id' => 5, 'sub-id' => 4),
array('id' => 6, 'sub-id' => 0),
array('id' => 7, 'sub-id' => 0),
array('id' => 8, 'sub-id' => 6),
array('id' => 9, 'sub-id' => 8),
array('id' => 10, 'sub-id' => 8)
);
and the logic here is
if sub-id of any element is equal to the id of another element,
then the array goes into the sub key of the parent element. i.e. sub-id 1 should go in 'sub' element of id 1 and sub-id 3 should go in 'sub' element of id 3
The required output of the above array is:
$requiredArray = array(
array('id' => 1,'sub-id' => 0,
'sub' => array(
array('id' => 3,'sub-id' => 1,
'sub' => array(
array('id' => 4,'sub-id' => 3,
'sub' => array(
array('id' => 5,'sub-id' => 4)
)
)
)
)
)
),
array('id' => 2,'sub-id' => 0),
array('id' => 6,'sub-id' => 0,
'sub' => array(
array('id' => 8,'sub-id' => 6,
'sub' => array(
array('id' => 9,'sub-id' => 8),
array('id' => 10,'sub-id' => 8)
)
)
)
),
array('id' => 7,'sub-id' => 0)
);
What have I tried so far
// $original array is the array shown above
function compare_subid($a, $b)
{
if ($a['sub-id'] == $b['sub-id']) return 0;
return ($a['sub-id'] < $b['sub-id']) ? -1 : 1;
}
usort($originalArray, 'compare_subid');
$newArray = array();
$newArray = create_multidimensional($originalArray, $newArray);
function create_multidimensional($originalArray, $newArray = null)
{
if ($newArray == null) $newArray = array();
array_walk($originalArray, function ($value, $key) use (&$newArray) {
//e($value);
if ($value['sub-id'] == 0) {
$newArray[] = $value;
} else {
foreach ($newArray as &$v) {
if ($v['id'] == $value['sub-id']) {
$v['sub'] = $value;
} else {
// not sure what to put here
}
}
}
});
return $newArray;
}
With this i am able to achieve a part of the $requiredArray which is as follows:
Array
(
[0] => Array
(
[id] => 6
[sub-id] => 0
[sub] => Array
(
[id] => 8
[sub-id] => 6
)
)
[1] => Array
(
[id] => 7
[sub-id] => 0
)
[2] => Array
(
[id] => 2
[sub-id] => 0
)
[3] => Array
(
[id] => 1
[sub-id] => 0
[sub] => Array
(
[id] => 3
[sub-id] => 1
)
)
)
Not sure if this is the correct method to use or there is any better way to do so.
If what I am doing is correct, I am not able to figure out what to input in the else statement of create_multidimensional function that I have created.

Answer 1

There is an easy way using references and only remove the ones with a sub-id at the very end:
// We need keys to be able to quickly map our assignments
foreach ($originalArray as $val) {
$array[$val["id"]] = $val;
}
// we first assign the arrays in a non-destructive way, so that we can easily find the
// appropriate key in the array
foreach ($array as $key => $val) {
if ($val["sub-id"] !== 0) {
$array[$val["sub-id"]]["sub"][] = &$array[$key];
}
}
// remove the ones from the first dimension which are somewhere deeper
foreach ($array as $key => $val) {
if ($val["sub-id"] !== 0) {
unset($array[$key]);
}
}

Answer 2

This is why objects in PHP are cool.
// Format all data into objects keyed by id
$input = array();
foreach ($originalArray as $el) {
$input[ $el['id'] ] = (object)($el + array('sub' => array()));
}
$result = array();
foreach ($input as $el) {
$sid = $el->{'sub-id'};
// Parent object: into result root
if ( !$sid ) {
$result[] = $el;
}
// Child object: into other object
else {
$input[$sid]->sub[] = $el;
}
}
print_r($result);
The obvious downside is that objects use ->prop syntax, which doesn't work well with -, so you have to ugly it: $el->{'sub-id'}.
And of course the result is a bunch of objects. May not be what you want.
Result (http://3v4l.org/8VMJr):
Array
(
[0] => stdClass Object
(
[id] => 1
[sub-id] => 0
[sub] => Array
(
[0] => stdClass Object
(
[id] => 3
[sub-id] => 1
[sub] => Array
(
[0] => stdClass Object
(
[id] => 4
[sub-id] => 3
[sub] => Array
(
[0] => stdClass Object
(
[id] => 5
[sub-id] => 4
[sub] => Array
(
)
)
)
)
)
)
)
)
[1] => stdClass Object
(
[id] => 2
[sub-id] => 0
[sub] => Array
(
)
)
[2] => stdClass Object
(
[id] => 6
[sub-id] => 0
[sub] => Array
(
[0] => stdClass Object
(
[id] => 8
[sub-id] => 6
[sub] => Array
(
[0] => stdClass Object
(
[id] => 9
[sub-id] => 8
[sub] => Array
(
)
)
[1] => stdClass Object
(
[id] => 10
[sub-id] => 8
[sub] => Array
(
)
)
)
)
)
)
[3] => stdClass Object
(
[id] => 7
[sub-id] => 0
[sub] => Array
(
)
)
)