php: combine multiple arrays value into one array preserving keys

Question

I have multiple arrays structured like these:

$array1 = ["aaa" => 1, "bbb" => 1];
$array2 = ["aaa" => 12, "bbb" => 12];
$array3 = ["bbb" => 15, "ccc" => 15];

meaning:

• every array has the same value for each key (eg: array1 has value "1" for every item in the array) but there are no arrays sharing the same value (eg: if array1 has value 1, then none of the other arrays has value = 1)
• the arrays may or may not share the same keys

I need to combine these arrays in a way that the final result is something like this:

$result = [
    "aaa" => [1,12],
    "bbb" => [1,12,15],
    "ccc" => [15],
];

meaning:

• the final array must contain all the keys from the previous arrays
• the value of the key is an array composed of all the values of the previous arrays that shared the same key

I know it's a bit messy, but I hope it is clear enough. I'm struggling to build the $result array. I tried merge, combine, intersect, but none of them seems to work. Is there a way to build the $result array without using a loop?

Thanks

Answer 1

Does it match your goal ?

<?php
    $array1 = ["aaa" => 1, "bbb" => 1];
    $array2 = ["aaa" => 12, "bbb" => 12];
    $array3 = ["bbb" => 15, "ccc" => 15];

    $array = array_merge_recursive($array1, $array2, $array3);
    
    print_r($array);
?>

outputs

Array
(
    [aaa] => Array
        (
            [0] => 1
            [1] => 12
        )

    [bbb] => Array
        (
            [0] => 1
            [1] => 12
            [2] => 15
        )

    [ccc] => 15
)

Answer 2

Merge all of array into an mergedArray. Then use 2 foreach to set it.

<?php

$array1 = ["aaa" => 1, "bbb" => 1];
$array2 = ["aaa" => 12, "bbb" => 12];
$array3 = ["bbb" => 15, "ccc" => 15];

$mergedArray = [$array1, $array2, $array3];


$result = [];
foreach ($mergedArray as $array) {
    foreach ($array as $key => $item) {
        $result[$key][] = $item;
    }
}

echo '<pre>';
print_r($result);
echo '</pre>';
exit;

?>

The result:

Array
(
    [aaa] => Array
        (
            [0] => 1
            [1] => 12
        )

    [bbb] => Array
        (
            [0] => 1
            [1] => 12
            [2] => 15
        )

    [ccc] => Array
        (
            [0] => 15
        )

)