Convert 2d array by specified 2d format - php

Question

I need to convert the below 2d array in to specified 2d array format. Array contains multiple parent and multiple child array. Also, have tried to convert the code, but am not getting the expected output.
This is the code what i have tried,
$a1 = array(
'0' =>
array(
'banner_details' =>
array(
'id' => 2,
'section_id' => 24
),
'slide_details' =>
array(
0 => array(
'id' => 74,
'name' => 'Ads1'
),
1 => array(
'id' => 2,
'name' => 'Ads2'
)
)
),
'1' =>
array(
'banner_details' =>
array(
'id' => 106,
'section_id' => 92
),
'slide_details' =>
array(
0 => array(
'id' => 2001,
'name' => 'Adv1'
),
1 => array(
'id' => 2002,
'name' => 'Adv2'
)
)
)
);
$s = [];
for($i = 0; $i<2; $i++) {
foreach($a1[$i]['slide_details'] as $vs){
$s[] = $vs;
}
}
My output:
Array
(
[0] => Array
(
[id] => 74
[name] => Ads1
)
[1] => Array
(
[id] => 2
[name] => Ads2
)
[2] => Array
(
[id] => 2001
[name] => Adv1
)
[3] => Array
(
[id] => 2002
[name] => Adv2
)
)
Expected output:
Array
(
[24] => Array
(
[0] => 74
[1] => 2
)
[92] => Array
(
[0] => 2001
[1] => 2002
)
)
please check the above code and let me know.
Thanks,

Answer 1

You can apply next simple foreach loop with help of isset() function:
foreach($a1 as $data){
if (isset($data['banner_details']['section_id'])){
$s[$data['banner_details']['section_id']] = [];
if (isset($data['slide_details'])){
foreach($data['slide_details'] as $row){
$s[$data['banner_details']['section_id']][] = $row['id'];
}
}
}
}
Demo
If you know that indexes like banner_details or slide_details or section_id will be there always then you can skip isset() in if statements.

Answer 2

You can use array_column function for simple solution:
$result = [];
foreach ($a1 as $item)
{
$result[$item['banner_details']['section_id']] = array_column($item['slide_details'], 'id');
}
var_dump($result);