Best way to add an element to every array in a mutidimentional array in PHP

Question

I want to add an element to every array in my multidimensional array.

My array is like this:

 Array
(
    [0] => Array
        (
            [RatingFactorPreferenceID] => 10
            [PreferenceID] => 45
            [RatedValue] => 1
            [CreatedOn] => 1326779061
            [CreatedBy] => 25
        )

    [1] => Array
        (
            [RatingFactorPreferenceID] => 20
            [PreferenceID] => 45
            [RatedValue] => 2
            [CreatedOn] => 1326779061
            [CreatedBy] => 25
        )

)

I want to add [RatingID] => 2 to both arrays, then my final array would look like:

 Array
(
    [0] => Array
        (
            [RatingID] => 2
            [RatingFactorPreferenceID] => 10
            [PreferenceID] => 45
            [RatedValue] => 1
            [CreatedOn] => 1326779061
            [CreatedBy] => 25
        )

    [1] => Array
        (
            [RatingID] => 2
            [RatingFactorPreferenceID] => 20
            [PreferenceID] => 45
            [RatedValue] => 2
            [CreatedOn] => 1326779061
            [CreatedBy] => 25
        )

)

I can loop over my array and do this, is there a better way to do this?

Answer 1

$array = array_map(function ($a) { return $a + array('RatingID' => 2); }, $array);

This still loops, but behind the scenes, if you prefer that.
You could also use array_walk , but that's really just looping disguised in a different syntax.

Answer 2

@deceze's answer is good but instantiating a second array and using the array union operator ( + ) is needlessly complex. Keep it simple:

$new_array = array_map(
  function( $inner_array ) {
    $inner_array[ 'RatingID' ] = 2;

    return $inner_array;
  },

  $orig_array
);

Answer 3

I think array_walk is the best option

$array = array(
            array(
                'RatingFactorPreferenceID' => 10,
                'PreferenceID' => 45,
                'RatedValue' => 1,
                'CreatedOn' => 1326779061,
                'CreatedBy' => 25
            ),
            array(
                'RatingFactorPreferenceID' => 20,
                'PreferenceID' => 45,
                'RatedValue' => 2,
                'CreatedOn' => 1326779061,
                'CreatedBy' => 25,
            )
        );

function AddAtTop(&$act_array,$key){

    $act_array = array_merge(array('RatingID'=>2), $act_array);
}

array_walk($array, 'AddAtTop');

echo '<pre>';
print_r($array);
echo '</pre>';

This should work for you.