How to calculate arrays of objects intersection with custom comparison function? - php

Question

I have two arrays of objects and I need to get array of objects which are present in both arrays, comparing them with custom callback function.
Here is my code:
<?php
class Some {
public $prop1;
public $prop2;
public function __construct($prop1, $prop2)
{
$this->prop1 = $prop1;
$this->prop2 = $prop2;
}
}
$arr1 = [new Some(1, 2), new Some(2, 3), new Some(3, 4)];
$arr2 = [new Some(2, 3), new Some(1, 2)];
$intersection = array_uintersect($arr1, $arr2, function ($el1, $el2) {
return ($el1->prop1 === $el2->prop1) && ($el1->prop2 === $el2->prop2) ? 0 : 1;
});
print_r($intersection);
And what I get is:
Array (
[1] => Some Object
(
[prop1] => 2
[prop2] => 3
)
)
While I obviously want to get two objects which props are identical ((1, 2) and (2, 3).
What's wrong with this uintersect? How to achieve what I need?

Answer 1

Intersect function first sorted arrays, so you need have understanding haw one object less than another, and return -1, 0, 1 as result of comparing. Else, if you only can answer that objects are equal or not, you should scan second array for each item of the first one – splash58 13 mins ago. Now result of the code depends on order of objects in your arrays
To use intersect function you can create a function to compare two objects as below
class Some {
public $prop1;
public $prop2;
static function compare($el1, $el2) {
$r = $el1->prop1 - $el2->prop1;
return $r ? $r : ($el1->prop2 - $el2->prop2);
}
public function __construct($prop1, $prop2)
{
$this->prop1 = $prop1;
$this->prop2 = $prop2;
}
}
$arr1 = [new Some(1, 2), new Some(2, 3), new Some(3, 4)];
$arr2 = [new Some(2, 3), new Some(1, 2)];
$intersection = array_uintersect($arr1, $arr2, ['Some','compare']);
print_r($intersection);
demo
UPDATE
If you don't want to make function to compare objects, PHP itself checks that such objects are equal. So you can use simple code with in_array function
$intersection = array();
foreach($arr1 as $x) {
if (in_array($x, $arr2)) {
$intersection[] = $x;
}
}
print_r($intersection);