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array_intersect_key
Computes the intersection of arrays using keys for comparison
(PHP 5 >= 5.1.0)
array_intersect_key() returns an array containing all the values of array1 which have matching keys that are present in all the arguments. Parameters
Return ValuesReturns an associative array containing all the values of array1 which have matching keys that are present in all arguments. ExamplesExample 250. array_intersect_key() example<?php The above example will output: array(2) {
In our example you see that only the keys
The two keys from the Code Examples / Notes » array_intersect_keyaidan
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 anton backer
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. gaylord dot aulke
I tried to use this function with PHP 5.0.4 under windows but the function does not seem to be implemented. (Fatal error: Call to undefined function array_intersect_key()) This works as a workaround for 2 arrays at least: function array_intersect_key($arr1, $arr2) { $res = array(); foreach($arr1 as $key=>$value) { if(array_key_exists($key, $arr2)) $res[$key] = $arr1[$key]; } return $res; } 17-jul-2006 01:31
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 $result; } } rod byrnes
Here is a faster version than those shown below, with optimisation for the case when only two arrays are passed. In my tests with a 10000 item first array and a 5000 item second array (run 20 times) this function ran in 1.89 seconds compared with 2.66 for the version posted by dak. For a three array case, same as above but with the third array containing 3333 values, the timing is 3.25 for this version compared with 3.7 for dak's version. <?php if (!function_exists('array_intersect_key')) { function array_intersect_key($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 $res; } } } ?> silvio ginter
Based on the code posted by gaylord dot aulke at 100days.de i wrote this one. This should implement this function in all versions equal or greater than PHP 4.0 function array_intersect_key($arr1, $arr2) { $res = array(); foreach($arr1 as $key=>$value) { $push = true; for ($i = 1; $i < func_num_args(); $i++) { $actArray = func_get_arg($i); if (gettype($actArray) != 'array') return false; if (!array_key_exists($key, $actArray)) $push = false; } if ($push) $res[$key] = $arr1[$key]; } return $res; } dak
A more efficient (and, I think, simpler) compatibility implementation: <?php if (!function_exists('array_intersect_key')) { function array_intersect_key ($isec, $arr2) { $argc = func_num_args(); for ($i = 1; !empty($isec) && $i < $argc; $i++) { $arr = func_get_arg($i); foreach ($isec as $k =>& $v) if (!isset($arr[$k])) unset($isec[$k]); } return $isec; } } ?> |
Change Languagearray_change_key_case array_chunk array_combine array_count_values array_diff_assoc array_diff_key array_diff_uassoc array_diff_ukey array_diff array_fill_keys array_fill array_filter array_flip array_intersect_assoc array_intersect_key array_intersect_uassoc array_intersect_ukey array_intersect array_key_exists array_keys array_map array_merge_recursive array_merge array_multisort array_pad array_pop array_product array_push array_rand array_reduce array_reverse array_search array_shift array_slice array_splice array_sum array_udiff_assoc array_udiff_uassoc array_udiff array_uintersect_assoc array_uintersect_uassoc array_uintersect array_unique array_unshift array_values array_walk_recursive array_walk array arsort asort compact count current each end extract in_array key krsort ksort list natcasesort natsort next pos prev range reset rsort shuffle sizeof sort uasort uksort usort |