问题
I'd like to merge two arrays with each other:
$filtered = array(1 => 'a', 3 => 'c');
$changed = array(2 => 'b*', 3 => 'c*');
Whereas the merge should include all elements of $filtered
and all those elements of $changed
that have a corresponding key in $filtered
:
$merged = array(1 => 'a', 3 => 'c*');
array_merge($filtered, $changed)
would add the additional keys of $changed
into $filtered
as well. So it does not really fit.
I know that I can use $keys = array_intersect_key($filtered, $changed)
to get the keys that exist in both arrays which is already half of the work.
However I'm wondering if there is any (native) function that can reduce the $changed
array into an array with the $keys
specified by array_intersect_key
? I know I can use array_filter
with a callback function and check against $keys
therein, but there is probably some other purely native function to extract only those elements from an array of which the keys can be specified?
I'm asking because the native functions are often much faster than array_filter
with a callback.
回答1:
This should do it, if I'm understanding your logic correctly:
array_intersect_key($changed, $filtered) + $filtered
Implementation:
$filtered = array(1 => 'a', 3 => 'c');
$changed = array(2 => 'b*', 3 => 'c*');
$expected = array(1 => 'a', 3 => 'c*');
$actual = array_key_merge_deceze($filtered, $changed);
var_dump($expected, $actual);
function array_key_merge_deceze($filtered, $changed) {
$merged = array_intersect_key($changed, $filtered) + $filtered;
ksort($merged);
return $merged;
}
Output:
Expected:
array(2) {
[1]=>
string(1) "a"
[3]=>
string(2) "c*"
}
Actual:
array(2) {
[1]=>
string(1) "a"
[3]=>
string(2) "c*"
}
回答2:
if you want the second array ($b) to be the pattern that indicates that if there is only the key there, then you could also try this
$new_array = array_intersect_key( $filtered, $changed ) + $changed;
来源:https://stackoverflow.com/questions/6562276/how-to-merge-two-arrays-by-taking-over-only-values-from-the-second-array-that-ha