Removing array item by value


Question

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?

1
159
12/10/2009 7:36:41 PM

Accepted Answer

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')

Hope it helps write beautiful code.

414
8/20/2013 10:05:17 PM

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]);
}

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