I have an array
Array(
[0] => Array
(
[0] => 33
[user_id] => 33
[1] => 3
[frame_id] => 3
)
[1] => Array
(
[0] => 33
[user_id] => 33
[1] => 3
[frame_id] => 3
)
[2] => Array
(
[0] => 33
[user_id] => 33
[1] => 8
[frame_id] => 8
)
[3] => Array
(
[0] => 33
[user_id] => 33
[1] => 3
[frame_id] => 3
)
[4] => Array
(
[0] => 33
[user_id] => 33
[1] => 3
[frame_id] => 3
)
)
As you can see key 0 is the same as 1, 3 and 4. And key 2 is different from them all.
When running the array_unique function on them, the only left is
Array (
[0] => Array
(
[0] => 33
[user_id] => 33
[1] => 3
[frame_id] => 3
)
)
Any ideas why array_unique isn't working as expected?
It's because array_unique
compares items using a string comparison. From the docs:
Note: Two elements are considered equal if and only if (string) $elem1 === (string) $elem2. In words: when the string representation is the same. The first element will be used.
The string representation of an array is simply the word Array
, no matter what its contents are.
You can do what you want to do by using the following:
$arr = array(
array('user_id' => 33, 'frame_id' => 3),
array('user_id' => 33, 'frame_id' => 3),
array('user_id' => 33, 'frame_id' => 8)
);
$arr = array_intersect_key($arr, array_unique(array_map('serialize', $arr)));
//result:
array
0 =>
array
'user_id' => int 33
'user' => int 3
2 =>
array
'user_id' => int 33
'user' => int 8
Here's how it works:
Each array item is serialized. This will be unique based on the array's contents.
The results of this are run through array_unique
,
so only arrays with unique
signatures are left.
array_intersect_key
will take
the keys of the unique items from
the map/unique function (since the source array's keys are preserved) and pull
them out of your original source
array.