Get intersection of a multi-dimensional array in PHP

Question

Starting Point

I have a multi-dimensional array, like the follow example:

$array = array (
  'role_1' => 
  array (
    0 => 'value_2',
    1 => 'value_3',
  ),
  'role_2' => 
  array (
    0 => 'value_1',
    1 => 'value_2',
  ),
  'role_3' => 
  array (
    0 => 'value_2',
    1 => 'value_3',
  ),
)

Goal

I like to loop about the sub-arrays to get only the intersection. The array was created dynamically, can have a lot of sub-arrays role_[x] and also a lot of key/value inside the sub-arrays. The key is not necessary, only the value. The key is also a count, not a string.

As result I like to get in this example this small array.

$array = array( 'value_2' )

The index, "the array-name", like role_1 of the sub-arrays is not more relevant after intersection. Important for me in the result is the values, only the values there are existed in each sub-array.

Try

I had tried with the source, but I think it is possible much simpler.

$value_stack = array();
$result = array();
$i = 0;
foreach( $settings_ as $role => $values ) {

    foreach( $values as $value ){

        if( in_array( $value,$value_stack ) || $i === 0 ) {
            $result[ $role ][] = $value;
        }

        $value_stack[] = $value;
    }
    $i++;

};

The merge of this multi array result should run with a array_merge in a loop.

Thanks for your time.

`$temp = $array[0]; for ($i = 1; $i < count($array) -1; $i++) { $temp = array_intersect($temp, $array[$i]); }` — Marc B, Jun 27 '16 at 14:15
Thanks for your fast hint, but this is always `NULL` in my tests. — bueltge, Jun 27 '16 at 14:18

score 12 · Accepted Answer · answered Jun 27 '16 at 14:24

You can use array_intersect to cover the dynamic $data as such:

$data = array (
  'role_1' => 
  array (
    0 => 'value_2',
    1 => 'value_3',
  ),
  'role_2' => 
  array (
    0 => 'value_1',
    1 => 'value_2',
  ),
  'role_3' => 
  array (
    0 => 'value_2',
    1 => 'value_3',
  )
);

$result = call_user_func_array('array_intersect', $data);

call_user_func_array will help spread the elements of your array as parameters inside array_intersect.

array_intersect() does not accept unknown named parameters - PHP Version 8 — Smart Boy, Mar 19 '23 at 15:57

score 7 · Answer 2 · edited Jun 27 '16 at 14:22

7

You should be able to do

call_user_func_array('array_intersect', $array_of_arrays)

This will pass each element of your array of arrays as an argument to array_intersect, which takes a variable number of arrays as arguments and returns their intersection.

edited Jun 27 '16 at 14:22

deceze

510,633
85
743
889

answered Jun 27 '16 at 14:17

Rose Kunkel

3,102
2
27
53

The result of this is always `NULL`. I had tried this. – bueltge Jun 27 '16 at 14:20
@bueltge Have you also tried with *`call_user_func_array`*? – deceze Jun 27 '16 at 14:22
Yes, sorry, it should have been `call_user_func_array`. – Rose Kunkel Jun 27 '16 at 14:22
1

For the protocol: at first the answer was with the function `call_user_func`. The switch to `call_user_func_array` is really helpful. Thanks in advice! – bueltge Jun 27 '16 at 14:29

score 1 · Answer 3 · answered Jun 27 '16 at 14:20

1

array_intersect work for this:

$data = array (
  'role_1' => 
  array (
    0 => 'value_2',
    1 => 'value_3',
  ),
  'role_2' => 
  array (
    0 => 'value_1',
    1 => 'value_2',
  ),
  'role_3' => 
  array (
    0 => 'value_2',
    1 => 'value_3',
  )
);


$result = array_intersect($data['role_1'], $data['role_2'], $data['role_3']);
print_r($result);

result :

Array ( [0] => value_2 )

answered Jun 27 '16 at 14:20

miglio

2,048
10
23

2

I'd assume the number of roles is unknown, so this call style is a bit impractical. – deceze Jun 27 '16 at 14:23

score 0 · Answer 4 · answered Sep 16 '21 at 21:20

As of PHP 5.6+ the splat/spread operator can be used to unpack the arguments in a call to array_intersect(). In order to remove the non-numeric keys from the array, pass $array to a call to array_values().

$result = array_intersect(...array_values($array));

See a demonstration in this playground example.

Get intersection of a multi-dimensional array in PHP

Starting Point

Goal

Try

4 Answers4

Linked