I have some troubles with an array. I have one array that I want to modify like below. I want to remove element (elements) of it by index and then re-index array. Is it possible?
$foo = array(
'whatever', // [0]
'foo', // [1]
'bar' // [2]
);
$foo2 = array(
'foo', // [0], before [1]
'bar' // [1], before [2]
);
Unset($array[0]);
Sort($array);
I don't know why this is being downvoted, but if anyone has bothered to try it, you will notice that it works.
Using sort on an array reassigns the keys of the the array. The only drawback is it sorts the values.
Since the keys will obviously be reassigned, even with array_values
, it does not matter is the values are being sorted or not.
array_splice($array, array_search(array_value, $array), 1);
array_splice($array, 0, 1);
In addition to xzyfer's answer
The function
function custom_unset(&$array=array(), $key=0) {
if(isset($array[$key])){
// remove item at index
unset($array[$key]);
// 'reindex' array
$array = array_values($array);
//alternatively
//$array = array_merge($array);
}
return $array;
}
Use
$my_array=array(
0=>'test0',
1=>'test1',
2=>'test2'
);
custom_unset($my_array, 1);
Result
array(2) {
[0]=>
string(5) "test0"
[1]=>
string(5) "test2"
}
Try with:
$foo2 = array_slice($foo, 1);
2020 Benchmark in PHP 7.4
For these who are not satisfied with current answers, I did a little benchmark script, anyone can run from CLI.
We are going to compare two solutions:
unset() with array_values() VS array_splice().
<?php
echo 'php v' . phpversion() . "\n";
$itemsOne = [];
$itemsTwo = [];
// populate items array with 100k random strings
for ($i = 0; $i < 100000; $i++) {
$itemsOne[] = $itemsTwo[] = sha1(uniqid(true));
}
$start = microtime(true);
for ($i = 0; $i < 10000; $i++) {
unset($itemsOne[$i]);
$itemsOne = array_values($itemsOne);
}
$end = microtime(true);
echo 'unset & array_values: ' . ($end - $start) . 's' . "\n";
$start = microtime(true);
for ($i = 0; $i < 10000; $i++) {
array_splice($itemsTwo, $i, 1);
}
$end = microtime(true);
echo 'array_splice: ' . ($end - $start) . 's' . "\n";
As you can see the idea is simple:
Output of the script above on my Dell Latitude i7-6600U 2.60GHz x 4 and 15.5GiB RAM:
php v7.4.8
unset & array_values: 29.089932918549s
array_splice: 17.94264793396s
Verdict: array_splice is almost twice more performant than unset and array_values.
So: array_splice is the winner!
After some time I will just copy all array elements (excluding these unwanted) to new array
If you use array_merge
, this will reindex the keys. The manual states:
Values in the input array with numeric keys will be renumbered with incrementing keys starting from zero in the result array.
http://php.net/manual/en/function.array-merge.php
This is where i found the original answer.
http://board.phpbuilder.com/showthread.php?10299961-Reset-index-on-array-after-unset()
You better use array_shift()
. That will return the first element of the array, remove it from the array and re-index the array. All in one efficient method.
Source: Stackoverflow.com