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array_intersect_key — 使用键名比较计算数组的交集
$array1
, array $array2
[, array $ ...
] ) array_intersect_key() 返回一个数组,该数组包含了所有出现在
array1
中并同时出现在所有其它参数数组中的键名的值。
array1
The array with master keys to check.
array2
An array to compare keys against.
array
A variable list of arrays to compare.
Returns an associative array containing all the entries of
array1
which have keys that are present in all
arguments.
Example #1 array_intersect_key() 例子
<?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 ));
?>
以上例程会输出:
array(2) { ["blue"]=> int(1) ["green"]=> int(3) }
上例中可以看到只有 'blue'
和 'green' 两个键名出现在两个数组中,因此被返回。此外注意
'blue' 和 'green'
的值在两个数组中是不同的。但因为只检查键名,因此还是匹配。返回的值只是
array1
中的。
在 key => value 对中的两个键名仅在 (string) $key1 === (string) $key2 时被认为相等。换句话说,执行的是严格类型检查,因此字符串的表达必须完全一样。
[#1] Mr. L [2015-10-20 04:33:55]
The $_GET array is:
print_r($_GET);
Array
(
[page] => 1
[keywords] => something
[search_in_description] => yes
[sort] => up
)
I would like to only allow the following keys, and want it in this particular order:
$allowed_array = array(
'keywords',
'search_in_description',
'page',
'sort'
);
$sorted_array = array_intersect_key($_GET, array_flip($allowed_array));
Then I get this:
print_r($sorted_array);
Array
(
[page] => 1
[keywords] => something
[search_in_description] => yes
[sort] => up
)
And below is what I hoped to get:
Array
(
[keywords] => something
[search_in_description] => yes
[page] => 1
[sort] => up
)
Can anyone tell me what I am doing wrong or what I should do in order to achieve what want?
Thanks.
[#2] Reed Silver [2015-03-02 23:38:44]
If you want an array that has no key value pairs added from the second array:
$new = array_intersect_key($b, $a) + $a;
[#3] github.com/xmarcos [2014-05-12 05:47:46]
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, $defaults
)
)
);
?>
Output:
array (size=4)
'id' => int 123456
'client_id' => int 789
'client_secret' => string '5ebe2294ecd0e0f08eab7690d2a6ee69' (length=32)
'options' =>
array (size=2)
'trusted' => boolean false
'active' => boolean true
[#4] pixelf3hler at visualize-me dot de [2013-09-28 08:08:48]
in case you came here looking for a function that returns an array containing the values of `all` arrays with intersecting keys:
<?php
function array_merge_on_key($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
?>
[#5] vladas dot dirzys at gmail dot com [2012-08-13 08:03:59]
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
)
[#6] pgl at yoyo dot org [2011-07-18 08:01:11]
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
)
[#7] chrisbloom7 at gmail dot com [2009-11-11 10:23:06]
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";
?>
[#8] markus dot kappe at dix dot at [2009-09-24 04:43:56]
<?php
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;
}
?>
[#9] pdemaziere at gmail dot com [2009-02-23 07:52:26]
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($mask)) ));
?>
PS: the array_values() function is necessary to ensure that both arrays have the same numbering/keys, otherwise your masking does not behave as you expect.
Enjoy!
[#10] CBWhiz at gmail dot com [2008-01-04 14:04:30]
I have found the following helpful:
<?PHP
function array_merge_default($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, $untrusted));
array(2) {
["two"]=>
int(2)
["one"]=>
int(42)
}
?>
[#11] Rod Byrnes [2007-05-05 21:10:42]
Here is a faster version than those shown below, with optimisation for the case when only two arrays are passed. In my tests with a 10000 item first array and a 5000 item second array (run 20 times) this function ran in 1.89 seconds compared with 2.66 for the version posted by dak. For a three array case, same as above but with the third array containing 3333 values, the timing is 3.25 for this version compared with 3.7 for dak's version.
<?php
if (!function_exists('array_intersect_key'))
{
function array_intersect_key($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;
}
}
}
?>
[#12] [2006-07-17 05:31:26]
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 $result;
}
}
[#13] Anton Backer [2006-03-30 23:49:50]
Jesse: no, array_intersect_key does not accomplish the same thing as what you posted:
array_flip (array_intersect (array_flip ($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.
[#14] aidan at php dot net [2005-05-29 08:51:02]
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