create new array from two arrays in php

Question

I have two arrays with the same keys, but different values.

Example:

(
    "2"=> 6,
    "5"=> 1
),
(
    "2"=> 1,
    "5"=> 3
)

I want to create a new array with the same keys, but replace the highest values like this:

 (
    "2"=> 6,
    "5"=> 3
)

What should I do?

Answer 1

You need to iterate getting the maximum value for each key, which you can do with a combination of array_keys, array_combine, array_map and array_column:

$keys = array_keys(reset($arr) ?: []);
$res = array_combine(
    $keys,
    array_map(fn ($k) => max(array_column($arr, $k)), $keys)
    );
print_r($res);

Output:

Array
(
    [2] => 6
    [5] => 3
)

Demo on 3v4l.org

For those using PHP prior to 7.4, you can replace the arrow function with

function ($k) use ($arr) { return max(array_column($arr, $k)); }

Note that this code assumes that all the sub-arrays have the same keys or some subset of the keys of the first sub-array.