is there a way to have array_column() keep the $input array key?

Question

Suppose I have an array of records, keyed by some ID, and I use the array_column() function to extract one piece of data from each record.

$records = array(
    1234 => array(
        'first_name' => 'John',
        'last_name' => 'Doe',
    ),
    4567 => array(
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ),
);

The result from array_column($input, 'first_name') is a numerically indexed array (with new keys 0, 1, ...). Is there a way of keeping the keys from the input array?

`$newArray = array_combine(array_keys($records), array_column($records, 'first_name'));` — Mark Baker, Jun 20 '17 at 13:55

user11927553 · Answer 1 · 2019-08-14T16:20:45.017

1

array_map(function ($r) { return $r['first_name']; }, $records)

will do (for your precise case).

It is more or less equivalent to this (PHP 7+):

(function () use ($records) {
    $result = [];
    foreach ($records as $key => $r) {
        $result[$key] = $r['first_name'];
    }
    return $result;
)()

edited Aug 14 '19 at 16:20

answered Aug 14 '19 at 13:20

user11927553

13
3

score 0 · Answer 2 · answered Jun 20 '17 at 13:58

0

When the id would also be available in the data array's you could use the third argument of array_column.

For example: array_column($records, 'first_name', 'id');

answered Jun 20 '17 at 13:58

Giso Stallenberg

942
7
10

2

Sorry, I should have made it clear - the desired data isn't available in the arrays, only as the key. – joachim Jun 21 '17 at 15:52

score 0 · Answer 3 · answered Dec 10 '21 at 23:28

Here's a simple function I often use:

function array_column_with_keys(array $array, string $column): array {
    return array_combine(
        array_keys($array), 
        array_column($array, $column));
}

So using your example array,

var_export(array_column_with_keys($records, 'first_name'));

will return:

array (
  1234 => 'John',
  4567 => 'Sally',
)

is there a way to have array_column() keep the $input array key?

3 Answers3