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up vote 0 down vote favorite

I have two arrays of the form

Array1:
[0]=> Array([name] => foo [id] => 12)
[1]=> Array([name] => bar [id] => 34)
Array2:
[0]=>Array([name] => bar [id]=> 34)
[1]=>Array([name] => baz [id]=> 56)

The arrays come from a database and any two pairs can have the same name but ID's are unique. I am trying to compare the arrays by ID likes so:

$one_not_two = array_diff($array1[id], $array2[id]);
but that does not return anything. I also tried
$one_not_two = array_diff($array1[id], $array2[id]);
which returned an error "argument is not an array." Originally I got around it by extracting the IDs into a one-dimensional array and just comparing those but now a new feature requires me to compare the pairs. Any advice?

PS Our servers are running php 5.3 if that makes any difference.

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2  
What are you trying to achieve? End goal? –  Sajuna Fernando Nov 13 '13 at 21:12
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4 Answers

up vote 2 down vote accepted

Because the arrays are multidimensional you have to extract the ids like this:

$ids1 = array();
foreach($array1 as $elem1)
    $ids1[] = $elem1['id'];

$ids2 = array();
foreach($array2 as $elem2)
    $ids2[] = $elem2['id'];

$one_not_two = array_diff($ids1,$ids2);

For your specific question, check out array_diff() with multidimensional arrays

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Thanks but I mentioned in my question that I tried something similar already. That would be an easy solution but something in the rest of the script requires $one_not_two to contain the mapping name => id. –  Yitzchak Nov 13 '13 at 21:21
    
Then you should look at this question: stackoverflow.com/questions/11821680/… –  Joren Nov 13 '13 at 21:29
    
Added your comment to the answer –  Yitzchak Nov 19 '13 at 14:36
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up vote 0 down vote

You could use array_udiff to create a custom diff function:

$diff = array_udiff($array1,
                    $array2,
                    function ($a, $b){
                        if($a['id'] == $b['id']){
                            return 0;
                        } else {
                            return ($a['id'] < $b['id'] ? -1 : 1);
                        }
                    }
                );

http://codepad.viper-7.com/2u5EWg

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up vote 0 down vote

If id is unique you can do that:

$one_not_two = array();

foreach ($array1 as $val) {
    $one_not_two[$val['id']] = $val;
}

foreach ($array1 as $val) {
    if (!isset($one_not_two[$val['id']])) {
        $one_not_two[$val['id']] = $val;
}
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up vote 0 down vote

In the end I solved it by changing Array1 to an associative array of name => id

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