I need to remove array item with given value:
if (in_array($id, $items)) {
$items = array_flip($items);
unset($items[ $id ]);
$items = array_flip($items);
}
Could it be done in shorter (more efficient) way?
Add a comment
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10 Answers
It can be accomplished with a simple one-liner.
Having this array:
$arr = array('nice_item', 'remove_me', 'another_liked_item', 'remove_me_also');
You can do:
$arr = array_diff($arr, array('remove_me', 'remove_me_also'));
And the value of $arr will be:
array('nice_item', 'another_liked_item')
answered Feb 13, 2012 at 22:12
Alejandro García Iglesias
16.4k11 gold badges53 silver badges66 bronze badges
8 Comments
Alejandro García Iglesias
No, it does works with referenced arrays, the
array_diff function is non-destructive, it returns a new array.Alejandro García Iglesias
@srcspider why not?
$referenced = array_diff($referenced, $items_to_remove);
srcspider
$referenced is now pointing to a new array, the array you wanted to change still has the old values.
Alejandro García Iglesias
@srcspider well, you tell me what's going on here then... codepad.org/11ZhiFP0
srcspider
my bad; php's variable aliasing gimmick always trips me over >.>
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I am adding a second answer. I wrote a quick benchmarking script to try various methods here.
$arr = array(0 => 123456);
for($i = 1; $i < 500000; $i++) {
$arr[$i] = rand(0,PHP_INT_MAX);
}
shuffle($arr);
$arr2 = $arr;
$arr3 = $arr;
/**
* Method 1 - array_search()
*/
$start = microtime(true);
while(($key = array_search(123456,$arr)) !== false) {
unset($arr[$key]);
}
echo count($arr). ' left, in '.(microtime(true) - $start).' seconds<BR>';
/**
* Method 2 - basic loop
*/
$start = microtime(true);
foreach($arr2 as $k => $v) {
if ($v == 123456) {
unset($arr2[$k]);
}
}
echo count($arr2). 'left, in '.(microtime(true) - $start).' seconds<BR>';
/**
* Method 3 - array_keys() with search parameter
*/
$start = microtime(true);
$keys = array_keys($arr3,123456);
foreach($keys as $k) {
unset($arr3[$k]);
}
echo count($arr3). 'left, in '.(microtime(true) - $start).' seconds<BR>';
The third method, array_keys() with the optional search parameter specified, seems to be by far the best method. Output example:
499999 left, in 0.090957164764404 seconds
499999left, in 0.43156313896179 seconds
499999left, in 0.028877019882202 seconds
Judging by this, the solution I would use then would be:
$keysToRemove = array_keys($items,$id);
foreach($keysToRemove as $k) {
unset($items[$k]);
}
2 Comments
kendepelchin
I think array_search is much more readable code than using the array_diff method. Upvote
General Redneck
@zombat I wonder if order has anything to do with the results. It is possible that shuffle put the value we are searching for either closer to the front or end. Other than that... +1
How about:
if (($key = array_search($id, $items)) !== false) unset($items[$key]);
or for multiple values:
while(($key = array_search($id, $items)) !== false) {
unset($items[$key]);
}
This would prevent key loss as well, which is a side effect of array_flip().
1 Comment
Marek
won't work if $id is first array element, better this way: if ( ($key = array_search($id, $items)) !== false) unset($items[$key]);
to remove $rm_val from $arr
unset($arr[array_search($rm_val, $arr)]);
Comments
The most powerful solution would be using array_filter, which allows you to define your own filtering function.
But some might say it's a bit overkill, in your situation...
A simple foreach loop to go trough the array and remove the item you don't want should be enough.
Something like this, in your case, should probably do the trick :
foreach ($items as $key => $value) {
if ($value == $id) {
unset($items[$key]);
// If you know you only have one line to remove, you can decomment the next line, to stop looping
//break;
}
}
Comments
Your solutions only work if you have unique values in your array
See:
<?php
$trans = array("a" => 1, "b" => 1, "c" => 2);
$trans = array_flip($trans);
print_r($trans);
?>
A better way would be unset with array_search, in a loop if neccessary.
1 Comment
Marek
you are right, but in this particular case I'm pretty sure that values are unique :)
w/o flip:
<?php
foreach ($items as $key => $value) {
if ($id === $value) {
unset($items[$key]);
}
}
Comments
function deleteValyeFromArray($array,$value)
{
foreach($array as $key=>$val)
{
if($val == $value)
{
unset($array[$key]);
}
}
return $array;
}
Comments
You can use array_splice function for this operation Ref : array_splice
array_splice($array, array_search(58, $array ), 1);
