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array_intersect_key

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

array_intersect_keyCalcula la intersección de arrays usando sus claves para la comparación

Descripción

array_intersect_key(array $array1, array $array2, array $... = ?): array

array_intersect_key() devuelve un array que contiene todos los valores de array1 que tienen claves que están presentes en todos los argumentos.

Parámetros

array1

El array con las claves maestras para verificar.

array2

Un array con el que comparar las claves.

...

Una lista variable de arrays para comparar.

Valores devueltos

Devuelve un array asociativo que contiene todas las entradas de array1 que tienen claves que están presentes en todos los argumentos.

Ejemplos

Ejemplo #1 Ejemplo de array_intersect_key()

<?php
$array1
= array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8);

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

El resultado del ejemplo sería:

array(2) {
  ["blue"]=>
  int(1)
  ["green"]=>
  int(3)
}

En el ejemplo se puede ver que sólo las claves 'blue' y 'green' están presentes en ambos arrays, por lo que son devueltas. Observe también que los valores de las claves 'blue' y 'green' difieren entre los dos arrays. Sigue habiendo coincidencia porque solamente se verifican las claves. Los valores devueltos son los de array1.

Las dos claves de los pares clave => valor son consideradas iguales sólo si (string) $clave1 === (string) $clave2 . En otras palabras se ejecuta una verificación estricta de tipos, por lo que la representación del string debe ser la misma.

Ver también

  • array_diff() - Calcula la diferencia entre arrays
  • array_udiff() - Computa la diferencia entre arrays, usando una llamada de retorno para la comparación de datos
  • array_diff_assoc() - Calcula la diferencia entre arrays con un chequeo adicional de índices
  • array_diff_uassoc() - Calcula la diferencia entre arrays con un chequeo adicional de índices que se realiza por una función de devolución de llamada suministrada por el usuario
  • array_udiff_assoc() - Computa la diferencia entre arrays con una comprobación de indices adicional, compara la información mediante una función de llamada de retorno
  • array_udiff_uassoc() - Computa la diferencia entre arrays con una verificación de índices adicional, compara la información y los índices mediante una función de llamada de retorno
  • array_diff_key() - Calcula la diferencia entre arrays empleando las claves para la comparación
  • array_diff_ukey() - Calcula la diferencia entre arrays usando una función de devolución de llamada en las keys para comparación
  • array_intersect() - Calcula la intersección de arrays
  • array_intersect_assoc() - Calcula la intersección de arrays con un chequeo adicional de índices
  • array_intersect_uassoc() - Calcula la intersección de arrays con una comprobación adicional de índices, los cuales se comparan con una función de retrollamada
  • array_intersect_ukey() - Calcula la intersección de arrays usando una función de devolución de llamada en las claves para la comparación

add a note

User Contributed Notes 11 notes

up
267
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
)
up
11
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
)
up
22
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
up
4
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;
up
11
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
)
up
6
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)
}

?>
up
3
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.
up
1
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";
?>
up
0
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
$master;
}
?>
up
-2
pixelf3hler at visualize-me dot de
11 years ago
in case you came here looking for a function that returns an array containing the values of `all` arrays with intersecting keys:
<?php
function array_merge_on_key($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
?>
up
-3
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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