I have a multidimensional array containing three arrays and an array of id's within each. Here is what it looks like:
$data = array(
'first' => array(1,2,3,4,5,6),
'second' => array(1,2,3),
'third' => array(1,2,5,6)
);
What I'd like to do is run an intersection on all three and end up with the result of an array, in this example, would be array(1,2)
How do I accomplish this?
$newArray = array_values(call_user_func_array("array_intersect", $data));
array_intersect returns the identical values of all the arrays passed, so you can pass the entries of $data as arguments to it. array_values is needed for reindexing as the keys won't be changed (not necessary, but helpful when you use the resulting array in a for loop).
using array_reduce and array_intersect.
$v = array_values($data);
$r = array_slice($v, 1);
$result = array_reduce($r, 'array_intersect', $v[0]);
var_dump($result);
Here is a one-liner.
array_reduce(array_slice($data, 0, -1), 'array_intersect', end($data));
call_user_func_array, though.
array_intersect on same elements twice. This was prevented by using array_slice.what about the following approach:
$comp = null;
foreach ($data as $arr) {
if ($comp === null) {
$comp = $arr;
continue;
} else {
$comp = array_intersect($comp, $arr);
}
}
//$comp no contains all the unique values;
btw: works with any count of $data except $data = null
The simplest way to solve this is with array_reduce:
function process($result, $item) {
return is_null($result) ? $item : array_intersect($result, $item);
}
$result = array_reduce($data, 'process');
Or use array_reduce with an anonymous function like this:
$result = array_reduce($data, function($result, $item) {
return is_null($result) ? $item : array_intersect($result, $item);
});
This last solution has the advantage of not needing to reference a function (built-in or otherwise) using a string containing the function name.
