Reformat array without temp variable

Question

I have the next array

[
    ['id' => 30, 'count' => 3],
    ['id' => 45, 'count' => 7]
]

I need it to be

[
    30 => ['count' => 3],
    45 => ['count' => 7]
]

What I did

$formatted = [];
foreach ($services as $service) {
    $formatted[$service['id']] = [
        'count' => $service['count']
    ];
}

What I'd like is a more elegant solution without the temporary $formatted variable. Thanks!

Update. Thanks a lot @rtrigoso ! With the laravel collection, my code looks next

$services->reduce(function ($carry, $item) {
        $carry[$item['id']] = ['count' => $item['count']];
        return $carry;
    });

Why though? If you don't use a third variable and update the main array directly... You might overwrite indexes. For example, if you have an id 30, but also have an item at index 30, it will overwrite it when you set the id. — Chin Leung
– Chin Leung, Commented Aug 15, 2017 at 13:48
Just feel that there should be a more elegant and right way to do it. Something like $formatted = array_magic($array, 'id') — cleverketchup
– cleverketchup, Commented Aug 15, 2017 at 13:55

iainn · Accepted Answer · 2017-08-15 14:09:33Z

5

You can do this in one line with array_column:

$array = array_column($array, null, 'id');

The one difference between your desired output is that this will still contain the id key in the second level of the array, like so:

[
    30 => ['id' => 30, 'count' => 3],
    45 => ['id' => 45, 'count' => 7],
]

but that hopefully shouldn't cause any problems. If you do need to remove it, you can do it with something like:

$array = array_map(function ($e) {
    unset($e['id']);
    return $e;
}, $array);

This approach is probably best if your rows could potentially have a lot more keys in them in future, i.e. it's quicker to list the keys to remove rather than the ones to keep. If not, and you'll only have a count, then to be honest your original example is probably the best you'll get.

edited Aug 15, 2017 at 14:09

answered Aug 15, 2017 at 13:53

iainn

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2 Comments

Andreas Over a year ago

In my opinion this is good, I can't see a reason why the second layer array is needed at all. What is wrong with[30] => "3"?

cleverketchup Over a year ago

But I need to get rid of 'id' key. That is the catch.

ren.rocks · Accepted Answer · 2017-08-15 13:58:47Z

2

You can use array_reduce

$x_arr = array(
    array('id' => 30, 'count' => 3),
    array('id' => 45, 'count' => 7),
);

$y_arr = array_reduce($x_arr, function ($result, $item) {
    $result[$item['id']] = array('count' => $item['count']);
    return $result;
}, array());

print_r($y_arr);

It will give you your desired result:

Array
(
    [30] => Array
    (
        [count] => 3
    )

    [45] => Array
    (
        [count] => 7
    )
)

answered Aug 15, 2017 at 13:58

ren.rocks

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