find, save and remove duplicate values from more then one array - php

Question

first array
[0]=> Brian
[1]=> A
[2]=> Leo
[3]=> A
[4]=> Mike
second array
[0]=> 1
[1]=> 2
[2]=> 3
[3]=> 4
[4]=> 5
I want to check if in first array there are duplicates, if yes, save only the first occurrence of that value, the other removes, remember those keys, and delete them from the second array too. In the end i want to have
first array
[0]=> Brian
[1]=> A
[2]=> Leo
[3]=> Mike
second array
[0]=> 1
[1]=> 2
[2]=> 3
[3]=> 5
I tried with this but second array does not have duplicates so it won't work for both array:
array_values(array_unique($array));

Answer 1

You did
array_values(array_unique($array));
This will give unique values of $array, but you won't find which index of second array needs to be unset.
Approach #1:
Your best shot is a simple for loop with an isset check. If we find the value already present in our $set(a new temp array), we unset that index from both original arrays, else we preserve it.
Snippet:
<?php
$arr1 = [
'Brian',
'A',
'Leo',
'A',
'Mike'
];
$arr2 = [
1,2,3,4,5
];
$set = [];
foreach($arr1 as $key => $value){
if(!isset($set[$value])) $set[$value] = true;
else{
unset($arr1[$key]); // foreach creates a copy of $arr1, so safe to unset
unset($arr2[$key]);
}
}
print_r($arr1);
print_r($arr2);
Demo: https://3v4l.org/BQ9mA
Approach #2:
If you don't like for loops, you can use array wrappers to do this. You can use array_combine to make first array values as keys and second array values as arrays. Note that this would only preserve the latest key value pairs, so we do a array_reverse to only maintain first occurrence pairs.
Snippet:
<?php
$arr1 = [
'Brian',
'A',
'Leo',
'A',
'Mike'
];
$arr2 = [
1,2,3,4,5
];
$filtered_data = array_combine(array_reverse($arr1),array_reverse($arr2));
print_r(array_keys($filtered_data));
print_r(array_values($filtered_data));
Demo: https://3v4l.org/mlstg

Answer 2

This simply builds a temp array using the values from your 2 arrays.
Because we use values of $a1 as the key, dups get overwritten and therefore lost. The array_keys_exists() check makes sure the first Dup is used and not subsequent dups. Then we just split the array into the two input arrays.
$a1 = ['Brian', 'A', 'Leo', 'A', 'Mike'];
$a2 = [1,2,3,4,5];
#temp array created using values of $a1 as key so dups get dropped because they are reused
foreach ($a1 as $i=>$a) {
if ( ! array_key_exists($a, $new)){
$new[$a] = $a2[$i];
}
}
$a1 = array_keys($new);
$a2 = array_values($new);
print_r($a1);
print_r($a2);
RESULT:
Array
(
[0] => Brian
[1] => A
[2] => Leo
[3] => Mike
)
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 5
)

Answer 3

Please note that array_unique preserves keys so you can easily use it to filter the second array too:
$firstArray = array_unique($firstArray);
$secondArray = array_intersect_key($secondArray, $firstArray);
var_dump(array_values($firstArray), array_values($secondArray));
From the docs of array_unique:
Note that keys are preserved. If multiple elements compare equal under the given sort_flags, then the key and value of the first equal element will be retained.