Multidimensional associative array intersection php

Question

I have two multidimensional arrays

$array1 = Array (
   [a1] => Array  (
           [a_name] => aaaaa
           [a_value] => aaa
         )

   [b1] => Array (
           [b_name] => bbbbb
           [b_value] => bbb
       )
   [c1] => Array (
           [c_name] => ccccc
           [c_value] => ccc
       )

 )

$array2 = Array (
     [b1] => Array (
           [b_name]=> zzzzz
         )
  )

I want the intersection of keys of $array1 and $array2. The result must be from $array1.

array_intersect_key doesnot do the multidimentional intersect — kcssm, Aug 29 '12 at 06:21
It intersects on the *keys*, it doesn't matter that the values are arrays. — deceze, Aug 29 '12 at 06:44

score 10 · Accepted Answer · edited Jul 29 '16 at 09:52

10

function recursive_array_intersect_key(array $array1, array $array2) {
    $array1 = array_intersect_key($array1, $array2);
    foreach ($array1 as $key => &$value) {
        if (is_array($value) && is_array($array2[$key])) {
            $value = recursive_array_intersect_key($value, $array2[$key]);
        }
    }
    return $array1;
}

Demo here.

edited Jul 29 '16 at 09:52

Community

1
1

answered Aug 29 '12 at 08:26

deceze

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706
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1

Thank you very much @deceze, this is exactly what i needed. You are awesome. – kcssm Aug 29 '12 at 08:41
How to do this if first is index array and second sub array is associative array? – FSShaikh Jan 05 '16 at 10:55
You need to check if the second parameter is an array as well to prevent type error(sending non-array values to back to the function) when the value is an array like this: ´if (is_array($value) && is_array($array2[$key])) {´ – Pelmered Jul 29 '16 at 09:59
Hi @deceze, how to add $array2 both are matching and not matching to $array2 – Krishna Jonnalagadda Aug 22 '18 at 05:47

score 1 · Answer 2 · answered Aug 29 '12 at 06:44

1

$output = array_intersect_key($array1, $array2);

answered Aug 29 '12 at 06:44

Stegrex

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19

Eric Leschinski · Answer 3 · 2015-02-17T22:06:52.980

Demo of 2 dimensional associative array intersection in PHP

The Code:

<?php
    function compare_states($a1, $a2){
        $diff1 = strcasecmp($a1['state_id'], $a2['state_id']);
        $diff2 = strcasecmp($a1['state_name'], $a2['state_name']);
        if ($diff1 != 0) return $diff1;
        if ($diff2 != 0) return $diff2;
        return 0;
    }
    function calculate_intersection($a1, $a2){
        return array_uintersect($a1, $a2, 'compare_states');
    }
?>

How to run it:

<?php
    $a = Array(Array("state_id"=>14, "state_name"=>"Illinois"));
    $b = Array(Array("state_id"=>14, "state_name"=>"Illinois"));
    $new = calculate_intersection($a, $b);
    print_r($a);
    //in this simple case, the intersection is equivalent to $a.
    $a = Array(Array("state_id"=>14, "state_name"=>"Illinois"));
    $b = Array(Array("state_id"=>14, "state_name"=>"Foobar"));
    $new = calculate_intersection($a, $b);
    print_r($a);
    //in this case, the intersection is empty.
?>

Unit tests to prove that the above code works as designed:

$a = Array();
$b = Array();
$new = calculate_intersection($a, $b);
print "\nGroup1\n";
print ((count($new) == count($a) && count($a) == count($b)) ? "." : "FAIL");
print ((count($new) == 0) ? "." : "FAIL");
//==============================================
$a = Array(Array("state_id"=>14, "state_name"=>"Illinois"));
$b = Array(Array("state_id"=>14, "state_name"=>"Illinois"));
$new = calculate_intersection($a, $b);
print "\nGroup2\n";
print ((count($new) == count($a) && count($a) == count($b)) ? "." : "FAIL");
print ((count($new) == 1) ? "." : "FAIL");
print (($new[0]['state_id'] == 14 ? "." : "FAIL"));
print (($new[0]['state_name'] == "Illinois" ? "." : "FAIL"));
//==============================================
print "\nGroup3\n";
$a = Array(Array("state_id"=>14, "state_name"=>"Illinois"), Array("state_id"=> "22", "state_name"=>"Massachusetts"));
$b = Array(Array("state_id"=>14, "state_name"=>"Illinois"), Array("state_id"=> "22", "state_name"=>"Massachusetts"));
$new = calculate_intersection($a, $b);
print ((count($new) == count($a) && count($a) == count($b)) ? "." : "FAIL");
print (($new[0]['state_id'] == 14 ? "." : "FAIL"));
print (($new[0]['state_name'] == "Illinois" ? "." : "FAIL"));
print (($new[1]['state_id'] == 22 ? "." : "FAIL"));
print (($new[1]['state_name'] == "Massachusetts" ? "." : "FAIL"));
//==============================================
$a = Array(Array("state_id"=>"14", "state_name"=>"Illinois"));
$b = Array(Array("state_id"=>"22", "state_name"=>"Massachusetts"));
$new = calculate_intersection($a, $b);
print "\nGroup5\n";
print ((count($new) == 0) ? "." : "FAIL");
//==============================================
$a = Array(Array("state_id"=>"14", "state_name"=>"Illinois"));
$b = Array(Array("state_id"=>"14", "state_name"=>"Illinois"), Array("state_id"=>"22", "state_name"=>"Massachusetts"));
$new = calculate_intersection($a, $b);
print "\nGroup6\n";
print ((count($new) == 1) ? "." : "FAIL");
print (($new[0]['state_id'] == 14) ? "." : "FAIL");
print (($new[0]['state_name'] == "Illinois") ? "." : "FAIL");
//==============================================
$a = Array(Array("state_id"=>"14", "state_name"=>"Illinois"));
$b = Array(Array("state_id"=>"22", "state_name"=>"Massachusetts"), Array("state_id"=>"14", "state_name"=>"Illinois"));
$new = calculate_intersection($a, $b);
print "\nGroup7\n";
print ((count($new) == 1) ? "." : "FAIL");
print (($new[0]['state_id'] == 14) ? "." : "FAIL");
print (($new[0]['state_name'] == "Illinois") ? "." : "FAIL");
//==============================================
$a = Array(Array("state_id"=>"14", "state_name"=>"Illinois"));
$b = Array(Array("state_id"=>"22", "state_name"=>"Massachusetts"), Array("state_id"=>"14", "state_name"=>"Fromulate"));
$new = calculate_intersection($a, $b);
print "\nGroup8\n";
print ((count($new) == 0) ? "." : "FAIL");
//==============================================
$a = Array(Array("state_id"=>"14", "state_name"=>"Illinois"), Array("state_id"=>"14", "state_name"=>"Illinois"));
$b = Array(Array("state_id"=>"14", "state_name"=>"Illinois"), Array("state_id"=>"14", "state_name"=>"Illinois"));
$new = calculate_intersection($a, $b);
print "\nGroup9\n";
print ((count($new) == 2) ? "." : "FAIL");
print (($new[0]['state_id'] == 14) ? "." : "FAIL");
print (($new[0]['state_name'] == "Illinois") ? "." : "FAIL");
print (($new[1]['state_id'] == 14) ? "." : "FAIL");
print (($new[1]['state_name'] == "Illinois") ? "." : "FAIL");
//==============================================
$a = Array(Array("state_id"=>"14", "state_name"=>"Illinois"), Array("state_id"=>"22", "state_name"=>"Massachusetts"));
$b = Array(Array("state_id"=>"22", "state_name"=>"Massachusetts"), Array("state_id"=>"14", "state_name"=>"Illinois"));
$new = calculate_intersection($a, $b);
print "\nGroup7\n";
print ((count($new) == 2) ? "." : "FAIL");
print (($new[0]['state_id'] == 14) ? "." : "FAIL");
print (($new[0]['state_name'] == "Illinois") ? "." : "FAIL");
print (($new[1]['state_id'] == 22) ? "." : "FAIL");
print (($new[1]['state_name'] == "Massachusetts") ? "." : "FAIL");
?>

The above code prints:

eric@dev $ php a.php
Group1
..
Group2
....
Group3
.....
Group5
.
Group6
...
Group7
...
Group8
.
Group9
.....
Group7
.....

All dots means everything passed.

What cases does this code take care of?

Both arrays being empty. Intersection is empty.
One empty and the other with items. Intersection is empty.
Both arrays have identical items, set: 1 and set: n. Intersection is equivalent to the first array.
Both arrays are identical, except shuffled. Intersection is equivalent to first array.
The arrays are identical except the state_name is different in each case, and the state_id is the same. Intersection is empty.
Array a has items uncommon to b, items common to B. Array b has items uncommon to a and items common to A. Intersection is the items common to both a and b.

What it doesn't do:

It doesn't test for nulls/undefined/dissimilar depth arrays, nor arrays 2 or more layers deep. If datatypes get swapped, comparing strings to ints, or floats to octals, it will probably fail. It's difficult to get PHP to do equality correctly. http://eev.ee/blog/2012/04/09/php-a-fractal-of-bad-design/

Do everything you can to try to do this work in the database, doing it in PHP blows the horn to summon the fail whale. It's inefficient, so you better not be operating on more than a few hundred items. It's going to surprise left jab you on unexpected cases, and it's kind of hard to read/understand what it's doing under the hood.

score -1 · Answer 4 · answered May 26 '14 at 17:46

I think you should check if the $array2[$key] is an array, too.

function recursive_array_intersect_key(array $array1, array $array2) {
    $array1 = array_intersect_key($array1, $array2);
    foreach ($array1 as $key => &$value) {
        if (is_array($value) && is_array($array2[$key])) {
            $value = recursive_array_intersect_key($value, $array2[$key]);
        }
    }
    return $array1;
}

Multidimensional associative array intersection php

4 Answers4

Demo of 2 dimensional associative array intersection in PHP

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