array_intersect_key

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

array_intersect_key — Ermittelt die Schnittmenge von Arrays, indem es die Schlüssel vergleicht

Beschreibung

array_intersect_key(array $array, array ...$arrays): array

array_intersect_key() gibt ein Array zurück, welches alle Werte von array enthält, die Schlüssel besitzen, die in allen anderen Argumenten enthalten sind.

Parameter-Liste

array: Das Array mit den Hauptschlüsseln, auf die geprüft werden soll.
arrays: Arrays zum Vergleichen der Schlüssel.

Rückgabewerte

Gibt ein assoziatives Array zurück, welches alle Einträge von array enthält, deren Schlüssel in allen weiteren Arrays vorhanden sind.

Changelog

Version	Beschreibung
8.0.0	Diese Funktion kann jetzt mit nur einem Parameter aufgerufen werden. Zuvor waren mindestens zwei Parameter erforderlich.

Beispiele

Beispiel #1 array_intersect_key()-Beispiel

<?php
$array1 = array('blau' => 1, 'rot'  => 2, 'grün' => 3, 'violett' => 4);
$array2 = array('grün' => 5, 'blau' => 6, 'gelb' => 7, 'türkis'  => 8);

var_dump(array_intersect_key($array1, $array2));
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

array(2) {
  ["blau"]=>
  int(1)
  ["grün"]=>
  int(3)
}

In unserem Beispiel ist zu sehen, dass nur die Schlüssel 'blau' und 'grün' in beiden Arrays vorhanden sind und daher zurückgegeben werden. Zu beachten ist auch, dass 'blau' und 'grün' in beiden Arrays unterschiedliche Werte besitzen. Eine Übereinstimmung wird dennoch festgestellt, da nur die Schlüssel geprüft werden. Die zurückgegebenen Werte sind diejenigen aus array.

Die beiden Schlüssel der Schlüssel => Wert-Paare werden genau dann als gleich erachtet, wenn (string) $key1 === (string) $key2 . Anders ausgedrückt findet eine strikte Prüfung statt, in der die String-Darstellungen gleich sein müssen.

Siehe auch

array_diff() - Ermittelt die Unterschiede zwischen Arrays
array_udiff() - Ermittelt den Unterschied zwischen Arrays mittels einer Callbackfunktion für den Datenvergleich
array_diff_assoc() - Berechnet den Unterschied zwischen Arrays mit zusätzlicher Indexprüfung
array_diff_uassoc() - Berechnet den Unterschied von Arrays mit zusätzlicher Indexprüfung, welche durch eine benutzerdefinierte Callback-Funktion vorgenommen wird
array_udiff_assoc() - Ermittelt den Unterschied zwischen Arrays mit zusätzlicher Indexprüfung, vergleicht mittels einer Callbackfunktion
array_udiff_uassoc() - Ermittelt den Unterschied zwischen Arrays mit zusätzlicher Indexprüfung, vergleicht Daten und Indizes mittels einer Callbackfunktion
array_diff_key() - Berechnet den Unterschied zwischen Arrays, indem es die Schlüssel vergleicht
array_diff_ukey() - Berechnet den Unterschied zwischen Arrays mittels einer Callbackfunktion für den Vergleich der Schlüssel
array_intersect() - Ermittelt die Schnittmenge von Arrays
array_intersect_assoc() - Ermittelt die Schnittmenge von Arrays mit zusätzlicher Indexprüfung
array_intersect_uassoc() - Ermittelt die Schnittmenge von Arrays mit Indexprüfung; vergleicht Indizes mit einer Callbackfunktion
array_intersect_ukey() - Ermittelt die Schnittmenge zweier Arrays mittels eines durch eine Callbackfunktion durchgeführten Schlüsselvergleiches

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User Contributed Notes 11 notes

down

265

vladas dot dirzys at gmail dot com ¶

12 years ago


Simple key white-list filter:



<?php

$arr = array('a' => 123, 'b' => 213, 'c' => 321);

$allowed = array('b', 'c');



print_r(array_intersect_key($arr, array_flip($allowed)));

?>



Will return:

Array

(

    [b] => 213

    [c] => 321

)

down

Anonymous ¶

3 years ago


Note that the order of the keys in the returned array is the same as the order of the keys in the source array.

To sort by the second array, then you may do so through array_replace.

<?php
$array = array(
    'two'   => 'a',
    'three' => 'b',
    'one'   => 'c',
    );

$keyswant = array(
    'one'       => '',
    'three'     => '',
    );

print_r(array_intersect_key(array_replace($keyswant, $array), $keyswant));

?>

Shows:

Array
(
    [one] => c
    [three] => b
)

Rather than:

Array
(
    [three] => b
    [one] => c
)

down

github.com/xmarcos ¶

10 years ago


[Editor's note: changed array_merge_recursive() to array_replace_recursive() to fix the script]



Here is a better way to merge settings using some defaults as a whitelist.



<?php



$defaults = [

    'id'            => 123456,

    'client_id'     => null,

    'client_secret' => null,

    'options'       => [

        'trusted' => false,

        'active'  => false

    ]

];



$options = [

    'client_id'       => 789,

    'client_secret'   => '5ebe2294ecd0e0f08eab7690d2a6ee69',

    'client_password' => '5f4dcc3b5aa765d61d8327deb882cf99', // ignored

    'client_name'     => 'IGNORED',                          // ignored

    'options'         => [

        'active' => true

    ]

];



var_dump(

    array_replace_recursive($defaults, 

        array_intersect_key(

            $options, $defaults

        )

    )

);



?>



Output:



array (size=4)

    'id'            => int 123456

    'client_id'     => int 789

    'client_secret' => string '5ebe2294ecd0e0f08eab7690d2a6ee69' (length=32)

    'options'       => 

        array (size=2)

            'trusted' => boolean false

            'active'  => boolean true

down

Reed Silver ¶

9 years ago


If you want an array that has no key value pairs added from the second array:

$new = array_intersect_key($b, $a) + $a;

down

pgl at yoyo dot org ¶

13 years ago


Note that the order of the keys in the returned array is the same as the order of the keys in the source array. eg:

<?php
$array = array(
    'two'   => 'a',
    'three' => 'b',
    'one'   => 'c',
    );

$keyswant = array(
    'one'       => '',
    'three'     => '',
    );

print_r(array_intersect_key($array, $keyswant));

?>

Shows:

Array
(
    [three] => b
    [one] => c
)

down

CBWhiz at gmail dot com ¶

16 years ago


I have found the following helpful:
<?PHP
function array_merge_default($default, $data) {
        $intersect = array_intersect_key($data, $default); //Get data for which a default exists
        $diff = array_diff_key($default, $data); //Get defaults which are not present in data
        return $diff + $intersect; //Arrays have different keys, return the union of the two
}
?>
It's use is like both of the functions it uses, but keeps defaults and _only_ defaults. It's designed for key arrays, and i'm not sure how it will work on numeric indexed arrays.

Example:
<?PHP
$default = array(
 "one" => 1,
 "two" => 2
);
$untrusted = array(
 "one" => 42,
 "three" => 3
);
var_dump(array_merge_default($default, $untrusted));

array(2) {
  ["two"]=>
  int(2)
  ["one"]=>
  int(42)
}

?>

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Anton Backer ¶

18 years ago


Jesse: no, array_intersect_key does not accomplish the same thing as what you posted:

array_flip (array_intersect (array_flip ($a), array_flip ($b)))

because when the array is flipped, values become keys. having duplicate values is not a problem, but having duplicate keys is. array_flip resolves it by keeping only one of the duplicates and discarding the rest. by the time you start intersecting, you've already lost information.

down

chrisbloom7 at gmail dot com ¶

14 years ago


Regarding php at keithtylerdotcom solution to emulate

<?php
$z = someFuncReturningAnArray()['some_key'];
?>

His recommended solution will still return an array. To get the value of a single key in an array returned by a function, simply add implode() to the recipe:

<?php
function someFuncReturningAnArray() {
  return array(
    'a' => 'b',
    'c' => 'd',
    'e' => 'f',
    'g' => 'h',
    'i' => 'j'
  );
}

//traditional way
$temp = someFuncReturningAnArray();
$b = $temp['a'];
echo print_r($b, 1) . "\n----------\n";

//keithtylerdotcom one-line method
$b = array_intersect_key(someFuncReturningAnArray(), array('a'=>''));
echo print_r($b, 1) . "\n----------\n";

//better one line method
$b = implode('', array_intersect_key(someFuncReturningAnArray(), array('a'=>'')));
echo print_r($b, 1) . "\n----------\n";
?>

down

markus dot kappe at dix dot at ¶

15 years ago


<?php
    /**
     * calculates intersection of two arrays like array_intersect_key but recursive
     *
     * @param  array/mixed  master array
     * @param  array        array that has the keys which should be kept in the master array
     * @return array/mixed  cleand master array
     */
    function myIntersect($master, $mask) {
        if (!is_array($master)) { return $master; }
        foreach ($master as $k=>$v) {
            if (!isset($mask[$k])) { unset ($master[$k]); continue; } // remove value from $master if the key is not present in $mask
            if (is_array($mask[$k])) { $master[$k] = $this->myIntersect($master[$k], $mask[$k]); } // recurse when mask is an array
            // else simply keep value
        }
        return $master;
    }
?>

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-2

pixelf3hler at visualize-me dot de ¶

11 years ago


in case you came here looking for a function that returns an array containing the values of `all` arrays with intersecting keys:
<?php
   function array_merge_on_key($key, $array1, $array2) {
      $arrays = array_slice(func_get_args(), 1);
      $r = array();
      foreach($arrays as &$a) {
         if(array_key_exists($key, $a)) {
            $r[] = $a[$key];
            continue;
         }
      }
      return $r;
   }
   // example:
   $array1 = array("id" => 12, "name" => "Karl");
   $array2 = array("id" => 4, "name" => "Franz");
   $array3 = array("id" => 9, "name" => "Helmut");
   $array4 = array("id" => 10, "name" => "Kurt");

   $result = array_merge_on_key("id", $array1, $array2, $array3, $array4);

   echo implode(",", $result); // => 12,4,9,10
?>

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-4

pdemaziere at gmail dot com ¶

15 years ago


Just a simple script if you want to use one array, which contains only zeros and ones, as mask for another one (both arrays must have the same size of course). $outcome is an array that contains only those values from $source where $mask is equal to 1.



<?php

$outcome = array_values(array_intersect_key( array_values($source), array_filter(array_values($mask)) ));

?>



PS: the array_values() function is necessary to ensure that both arrays have the same numbering/keys, otherwise your masking does not behave as you expect.



Enjoy!

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