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array_intersect_key

(PHP 5 >= 5.1.0)

array_intersect_keyErmittelt die Schnittmenge von Arrays, indem es die Schlüssel vergleicht

Beschreibung

array array_intersect_key ( array $array1 , array $array2 [, array $... ] )

array_intersect_key() gibt ein Array zurück, welches alle Werte von array1 enthält, die Schlüssel besitzen, die in allen anderen Argumenten enthalten sind.

Parameter-Liste

array1

Das Array mit den Hauptschlüsseln, auf die geprüft werden soll.

array2

Ein Array, gegen welches die Schlüssel geprüft werden.

...

Eine variable Liste zu vergleichender Arrays.

Rückgabewerte

Gibt ein assoziatives Array zurück, welches alle Einträge von array1 enthält, deren Schlüssel in allen weiteren Arrays vorhanden sind.

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 sehen Sie, dass nur die Schlüssel 'blau' und 'grün' in beiden Arrays vorhanden sind und daher zurückgegeben werden. Beachten Sie 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 array1.

Die beiden Schlüssel des Schlüssel => Wert-Paares werden als gleich erachtet, genau dann wenn (string) $key1 === (string) $key2 . Anders ausgedrückt findet eine strikte Prüfung statt, in der die String-Repräsentationen 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 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 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 12 notes

up
33
vladas dot dirzys at gmail dot com
2 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
)
up
2
CBWhiz at gmail dot com
6 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)
}

?>
up
1
pixelf3hler at visualize-me dot de
11 months 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
?>
up
0
github.com/xmarcos
4 months ago
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_merge_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
up
0
chrisbloom7 at gmail dot com
4 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";
?>
up
0
pdemaziere at gmail dot com
5 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!
up
0
Anonymous
8 years ago
Here it is a more obvious way to implement the function:

if (!function_exists('array_intersect_key')) {
    function array_intersect_key()
    {
        $arrs = func_get_args();
        $result = array_shift($arrs);
        foreach ($arrs as $array) {
            foreach ($result as $key => $v) {
                if (!array_key_exists($key, $array)) {
                    unset($result[$key]);
                }
            }
        }
        return $result;
   }
}
up
0
Anton Backer
8 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.
up
0
aidan at php dot net
9 years ago
This functionality is now implemented in the PEAR package PHP_Compat.

More information about using this function without upgrading your version of PHP can be found on the below link:

http://pear.php.net/package/PHP_Compat
up
-2
Rod Byrnes
7 years ago
Here is a faster version than those shown below, with optimisation for the case when only two arrays are passed. In my tests with a 10000 item first array and a 5000 item second array (run 20 times) this function ran in 1.89 seconds compared with 2.66 for the version posted by dak. For a three array case, same as above but with the third array containing 3333 values, the timing is 3.25 for this version compared with 3.7 for dak's version.

<?php
if (!function_exists('array_intersect_key'))
{
  function
array_intersect_key($isec, $keys)
  {
   
$argc = func_num_args();
    if (
$argc > 2)
    {
      for (
$i = 1; !empty($isec) && $i < $argc; $i++)
      {
       
$arr = func_get_arg($i);
        foreach (
array_keys($isec) as $key)
        {
          if (!isset(
$arr[$key]))
          {
            unset(
$isec[$key]);
          }
        }
      }
      return
$isec;
    }
    else
    {
     
$res = array();
      foreach (
array_keys($isec) as $key)
      {
        if (isset(
$keys[$key]))
        {
         
$res[$key] = $isec[$key];
        }
      }
      return
$res;
    }
  }
}
?>
up
-1
pgl at yoyo dot org
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. 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
)
up
-1
markus dot kappe at dix dot at
4 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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