Preserve keys when converting a 2d array with numeric keys to a 1d array

Question

I can't figure out how to correctly flatten this array; I lose the keys when I flatten using array_unique().

This is the original array:

[
    [2 => "Opnam"],
    [2 => "Opnam"],
    [2 => "Opnam"],
    [3 => "Voem"],
    [8 => "And"],
    [6 => "Vei"],
    [6 => "Vei"],
    [8 => "And"],
    [8 => "And"],
]

The is the expected output:

[
    2 => "Opnam"
    3 => "Voem"
    6 => "Vei"
    8 => "And"
]

Barmar · Accepted Answer · 2019-08-22 19:46:53Z

1

Get the key and value of the inner array, and use it as the key and value of the result.

$result = [];
foreach ($original as $inner) {
    foreach ($inner as $key => $value) {
        $result[$key] = $value;
    }
}

answered Aug 22, 2019 at 19:46

Barmar

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Comments

mickmackusa · Accepted Answer · 2025-03-19 09:34:00Z

0

Simply spread the rows inside of array_replace(). Differently from array_merge(), array_replace() will preserve the keys found in the second level. Demo

var_export(array_replace(...$array));

Output:

array (
  2 => 'Opnam',
  3 => 'Voem',
  8 => 'And',
  6 => 'Vei',
)

answered Mar 19 at 9:34

mickmackusa♦

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