Replace multidimensional array values with one-dimensional array

Question

I would like to change the values in one multidimensional array if a corresponding key is found in another flat, associative array.

I have these two arrays:

$full = [
    'Cars' => [
         'Volvo' => 0,
         'Mercedes' => 0,
         'BMW' => 0,
         'Audi' => 0
    ],
    'Motorcycle' => [
        'Ducati' => 0,
        'Honda' => 0,
        'Suzuki' => 0,
        'KTM' => 0
    ]
];

$semi = [
    'Volvo' => 1,
    'Audi' => 1
];

I want the array to look like this:

Array
(
    [Cars] => Array
        (
            [Volvo] => 1
            [Mercedes] => 0
            [BMW] => 0
            [Audi] => 1
        )

    [Motorcycle] => Array
        (
            [Ducati] => 0
            [Honda] => 0
            [Suzuki] => 0
            [KTM] => 0
        )
)

I get the $semi array back from my input field and want to merge it into $full to save it into my database.

I already tried array_replace() like:

$replaced = array_replace($full, $semi);

What if... Honda is both a car and a motorcycle, how would you know where to add it? — IT goldman
– IT goldman, Commented Jul 1, 2022 at 9:19
Those are just dummy values, normally, we have distinct values. Just changed it for the question here — Luiz_merano
– Luiz_merano, Commented Jul 1, 2022 at 9:20
The problem with accepting an answer too quickly is that you decrease the incentive for other contributor to add alternative answers. Please always present array data as var_export so that contributors can instantly use your data in their sandboxes. Now I have to waste my time retyping your input on my phone before I can test my suggested code. — mickmackusa
– mickmackusa ♦, Commented Jul 1, 2022 at 9:39
This might be an XY Problem. If you explain how your database table is configured, we may be able to avoid this whole task and just send this user-supplied data directly to your table with a well-crafted UPDATE query. — mickmackusa
– mickmackusa ♦, Commented Jul 1, 2022 at 10:14

Justinas · Accepted Answer · 2022-07-01 09:23:44Z

1

You should loop your $semi array and check if it exists in one of $full arrays, then add to it:

foreach ($semi as $semiItem => $semiValue) {
    foreach ($full as &$fullItems) {
        if (isset($fullItems[$semiItem])) {
            $fullItems[$semiItem] = $semiValue;
        }
    }
}

answered Jul 1, 2022 at 9:23

Justinas

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1 Comment

Luiz_merano Over a year ago

is it also possible to set all other values = 0 that are not in the $semi array?

mickmackusa · Accepted Answer · 2022-07-01 10:02:57Z

0

You only need to visit "leafnodes", it will be very direct to iterate and modify the full array with array_walk_recursive().

Modern "arrow function" syntax allows access to the semi array without writing use().

This approach makes absolutely no iterated function calls. It modifies $v by reference (&$v), uses the "addition assignment" combined operator (+=), and the null coalescing opetator (??) to conditionally increase values in the full array which are found in the semi array.

Code: (Demo)

array_walk_recursive(
    $full,
    fn(&$v, $k) => $v += $semi[$k] ?? 0
);

var_export($full);

Not using array_walk_recursive() would necessitate using nested loops to increase qualifying manufacturers.

Code: (Demo)

foreach ($full as &$manufacturers) {
    foreach ($manufacturers as $m => &$count) {
        $count += $semi[$m] ?? 0;
    }
}
var_export($full);

edited Jul 1, 2022 at 10:02

answered Jul 1, 2022 at 9:50

mickmackusa♦

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1 Comment

mickmackusa Over a year ago

If you are merely overwriting the counts (not adding them), you can use = instead of +=.

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