Cross compare two array elements - php

Question

After a lot of API calls and loops I have created an array. This array takes the following form
2 => array:3 [▼
"someInfo" => array:1 [▶]
"existingIDs" => array:1 [▼
0 => array:1 [▼
"id" => "123456"
]
]
"idList" => array:2 [▼
0 => array:1 [▼
"id" => "123456"
]
1 => array:1 [▼
"id" => "777564"
]
]
]
The part I am interested in is existingIDs and idList. The problem is that some ids are appearing in both array elements, so in the above example the id 123456 appears in both.
What I need to do is cross compare these two elements and perhaps create a new element with unique ids. So the above example may turn into something like this
2 => array:3 [▼
"someInfo" => array:1 [▶]
"existingIDs" => array:1 [▼
0 => array:1 [▼
"id" => "123456"
]
]
"idList" => array:2 [▼
0 => array:1 [▼
"id" => "123456"
]
1 => array:1 [▼
"id" => "777564"
]
]
"uniqueList" => array:2 [
0 => array:1 [
"id" => "123456"
]
1 => array:1 [
"id" => "777564"
]
]
]
How could something like this be achieved?
Thanks

Answer 1

Use the following approach with array_column(available since PHP 5.5), array_merge and array_unique functions:
$arr = [
"someInfo" => [],
"existingIDs" => [
["id" => "123456"]
],
"idList" => [
["id" => "123456"],
["id" => "777564"],
["id" => "777564"]
]
];
$all_ids = array_merge(array_column($arr['existingIDs'], 'id'), array_column($arr['idList'], 'id'));
$arr['uniqueList'] = array_unique($all_ids);
print_r($arr);
The output:
Array
(
[someInfo] => Array
(
)
[existingIDs] => Array
(
[0] => Array
(
[id] => 123456
)
)
[idList] => Array
(
[0] => Array
(
[id] => 123456
)
[1] => Array
(
[id] => 777564
)
[2] => Array
(
[id] => 777564
)
)
[uniqueList] => Array
(
[0] => 123456
[2] => 777564
)
)