Merge arrays in multidimensional array based on multiple values

Question

[
    0 => [
        'qty' => 10
        'section' => 'VK7B'
        'time_window' => 1
    ]
    1 => [
        'qty' => 1
        'section' => 'STIC'
        'time_window' => 1
    ]
    2 => [
        'qty' => 1
        'section' => 'STIC'
        'time_window' => 1
    ]
]

I have this multidimensional array where I want to merge the array's if both the section and the time_window are the same, summing the qty for that array. What is an elegant way to do this?

I have tried this ($sections being the multidimensional arry), but this changes the keys and only checks for one value:

$new = []
foreach ($sections as $s) {
   if (isset($new[$s['section']])) {
        $new[$s['section']]['qty'] += $s['qty'];
        $new[$s['section']]['time_window'] = $s['time_window'];
    } else {
        $new[$s['section']] = $s;
    }
}

[
    'VK7B' => [
        'qty' => 10
        'section' => 'VK7B'
        'time_window' => 1
    ]
    'STIC' => [
        'qty' => 2
        'section' => 'STIC'
        'time_window' => 1
    ]
]

Answer 1

As pointed by @RiggsFolly in the comment you are not checking time_window are the same.

You can do it with this code:

$new = []
foreach ($sections as $s) {
   // you need to save both values (section and time_window) to check both of them
   if (isset($new[$s['section'].$s['time_window']])) {
        $new[$s['section'].$s['time_window']]['qty'] += $s['qty'];
        $new[$s['section'].$s['time_window']]['time_window'] = $s['time_window'];
    } else {
        $new[$s['section'].$s['time_window']] = $s;
    }
}

// Now $new is an associative array => let's transform it in a normal array
$new = array_values($new);