Imagine having an array like this:
[
'key1' => 'Label 1',
'key2' => 'Label 2',
'key3' => 'Label 3'
];
How can I convert that into a multidimensional array like this:
[
'key1' => [
'key1' => 'Label 1',
'key2' => [
'key2' => 'Label 2',
'key3' => [
'key3' => 'Label 3',
],
],
],
];
I thought about something with a recursive function and array_shift, but I'm not sure how to code it.
The array shall be nested as deep as there are elements.
Here's a way to do it with a loop, maintaining a pointer into the output array so we can simply push values further into it:
$result = array();
$r = &$result;
foreach ($arr as $k => $v) {
$r[$k] = array($k => $v);
$r = &$r[$k];
}
print_r($result);
Output:
Array
(
[key1] => Array
(
[key1] => Label 1
[key2] => Array
(
[key2] => Label 2
[key3] => Array
(
[key3] => Label 3
)
)
)
)
Here's a recursive solution just for fun:
function nest(array $flat): array
{
// base
if (!$flat) return [];
// recursive
return [key($flat) => array_merge(array_splice($flat, 0, 1), nest($flat))];
}
In the base case when the input is empty, you return an empty array.
For the recursive case you return a key/value pair with
