PHP : How to remove a duplicate array item ONCE - php

Question

I have an array:
$arr1 = [1,2,2,3,3,3];
Is there any method by which I can delete a duplicate value once like,
some_function($arr1,3);
which gives me the ouput $arr1 = [1,2,2,3,3]

Answer 1

As per the comment, check if there are more than one of the element you're searching for, then find and remove one of them.
function remove_one_duplicate( $arr, $target ) {
if( count( array_keys( $arr, $target ) ) > 1 ) {
unset( $arr[array_search( $target, $arr )] );
}
return $arr;
}

Answer 2

This should work...
function removeduplicate($myarray,$needle) {
if (($nmatches = count($matches = array_keys($myarray,$needle))) >= 2) {
for ($i=0; $i<$nmatches; $i++) {
if ($matches[$i+1] == (1+$matches[$i])) {
array_splice($myarray,$matches[$i],1);
break;
}
}
}
return $myarray;
}
To use the function...
$arr1 = [1,2,2,3,3,3,4,7,3,3];
$newarray = removeduplicate($arr1,3)
print_r($newarray);
EDITED:
If you want the function to modify your original array directly, you can do it (the function will return true if a character has been removed or false if not)...
function removeduplicate(&$myarray,$needle) {
if (($nmatches = count($matches = array_keys($myarray,$needle))) >= 2) {
for ($i=0; $i<$nmatches; $i++) {
if ($matches[$i+1] == (1+$matches[$i])) {
array_splice($myarray,$matches[$i],1);
return true;
}
}
}
return false;
}
So, now you can do...
$arr1 = [1,2,2,2,2,2,3,3,3,4,2,2];
removeduplicate($arr1,2);
print_r($arr1);

Answer 3

This function will copy the array skipping only the second instance of the specified element.
function removeOnce($array, $elem) {
$found = 0;
$result = [];
foreach ($array as $x) {
if ($x == $elem && (++$found) == 2) {
continue;
}
$result[] = $x;
}
return $result;
}