Slicing a multi-dimensional PHP array across one of its elements

Question

Say for example you just queried a database and you recieved this 2D array.

$results = array(
    array(\'id\' => 1, \'name\' => \'red\'  , \'spin\' =&         


        

Answer 1

You could do:

$tmp = array_flip($names);
$names = array_keys($tmp);

Answer 2

If you are running a version of PHP before 5.5 and array_column(), you can use the official replacement in plain PHP:

https://github.com/ramsey/array_column

Answer 3

As of June 20th in PHP-5.5 there is a new function array_column

For example:

$records = array(
    array(
        'id' => 2135,
        'first_name' => 'John',
        'last_name' => 'Doe'
    ),
    array(
        'id' => 3245,
        'first_name' => 'Sally',
        'last_name' => 'Smith'
    ),
    array(
        'id' => 5342,
        'first_name' => 'Jane',
        'last_name' => 'Jones'
    ),
    array(
        'id' => 5623,
        'first_name' => 'Peter',
        'last_name' => 'Doe'
    )
);


$firstNames = array_column($records, 'first_name');
print_r($firstNames);

Will return

Array
(
    [0] => John
    [1] => Sally
    [2] => Jane
    [3] => Peter
)

There are even more examples in the above mentioned link.

Answer 4

Starting PHP 5.3, you can use this pretty call with lambda function:

$names = array_map(function ($v){ return $v['name']; }, $results);

This will return array sliced by 'name' dimension.

Answer 5

I did more research on this and found that ruby and prototype both have a function that does this called array_pluck,2. It's interesting that array_map has a second use that allows you to do the inverse of what i want to do here. I also found a PHP class someone is writing to emulate prototypes manipulation of arrays.

I'm going to do some more digging around and if I don't find anything else I'll work on a patch to submit to the internals@lists.php.net mailing list and see if they will add array_pluck.

Answer 6

For those of you that cannot upgrade to PHP5.5 right now and need this function, here is an implementation of array_column.

function array_column($array, $column){
    $a2 = array();
    array_map(function ($a1) use ($column, &$a2){
        array_push($a2, $a1[$column]);
    }, $array);
    return $a2;
}