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Digg  array_intersect_key
Computes the intersection of arrays using keys for comparison
(PHP 5 >= 5.1.0)
Example 250. array_intersect_key() example<?phpThe above example will output: array(2) {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; } } ?> |
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array_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 |
