2 arrays: keep only elements with different value - php

Question

I have 2 arrays:
Array
(
[0] => Array
(
[id] => 1
[fieldname] => banana
[value] => yellow
)
)
Array
(
[0] => Array
(
[id] => 1
[fieldname] => rome
[value] => city
)
[1] => Array
(
[id] => 2
[fieldname] => bla
[value] => yes
)
)
I want to create a new array that contains only elements where "id" is different. In other words I want to get this output:
Array
(
[0] => Array
(
[id] => 2
[fieldname] => bla
[value] => yes
)
)
[id] => 2 was the only different [id] so I keep it.
Said that I've already managed to achieve my goal with an inefficient pile of foreach, if statements and temp variables. I really don't want to use a wall of code for this very small thing so I started to look for a native PHP function with no success. What's the easiest way to get the result? Is it possible that I strictly need to use a foreach with so many if?

Answer 1

You can use array_udiff with a function.
Computes the difference of arrays by using a callback function for
data comparison.
Returns an array containing all the values of the first array that are not
present in any of the other arguments.
The code:
// Setup two arrays as per your question
$array1 = array (
'0' => array (
'id' => '1',
'fieldname' => 'banana',
'value' => 'yellow',
)
);
$array2 = array (
'0' => array (
'id' => '1',
'fieldname' => 'rome',
'value' => 'city',
),
'1' => array (
'id' => '2',
'fieldname' => 'bla',
'value' => 'yes',
)
);
// Setup the callback comparison function
function arrayCompare($array2, $array1) {
return $array2['id'] - $array1['id'];
}
// Use array_udiff() with the two arrays and the callback function
$arrayDiff = array_udiff($array2, $array1, 'arrayCompare');
print_r($arrayDiff);
The above code returns the following:
Array (
[1] => Array (
[id] => 2
[fieldname] => bla
[value] => yes
)
)

Answer 2

This should do it. Not super short and it does use a temporary variable, so perhaps not what you were looking for. I've named the two arrays one and two.
$ids = array();
$result = array();
foreach ($one as $x) {
$ids[$x['id']] = 1; //This way, isset($x['id']) vill return true
}
foreach ($two as $x) {
if (!isset($ids[$x['id']])) {
$result[] = $x;
}
}
I would be surprised if there wasn't an even more compact way to do it.
EDIT: This is an alternative variant with nested for each. Not particularly short either.
$result = array();
foreach ($one as $x) {
foreach ($two as $y) {
if ($x['id'] == $y['id']) {
//A match, lets try the next $x
continue 2;
}
}
//No matching id in $two
$result[] = $x;
}