Unify quantities in one item - php

Question

I have two arrays which have items and quantities and they are asociated by the index of the arrays. Example:
Items=XL,M,XL,S
Quantities=5,2,4,7
What I want to achieve is to remove the repetitive items and sum their quantities:
Items=XL,M,S
Quantities=9,2,7
$uniqueTallesTotalesC = array_unique($tallesTotalesC);
for($i=0;$i<Count($uniqueTallesTotalesC);$i++){
for($e=0;$e<Count($cantidadesTotalesC);$e++){
if($uniqueTallesTotalesC[$i]==$tallesTotalesC[$e] && $e > $i){
$cantidadesTotalesC[$i] = $cantidadesTotalesC[$i] + $cantidadesTotalesC[$e];
} else{
}
}
}

Answer 1

You can just blindly zip-merge them together with summation:
$items = explode(',', 'XL,M,XL,S');
$quantities = explode(',', '5,2,4,7');
if(count($items) !== count($quantities)){
throw new RuntimeException('Count mismatch');
}
$final = [];
for($i = 0; $i < count($items); $i++) {
if(!isset($final[$items[$i]])){
$final[$items[$i]] = 0;
}
$final[$items[$i]] += $quantities[$i];
}
var_dump($final);
Outputs:
array(3) {
["XL"]=>
int(9)
["M"]=>
int(2)
["S"]=>
int(7)
}
Demo: https://3v4l.org/6A5ZC
There's probably an autovivification that I'm missing that could simplify this greater.

Answer 2

I suggest you to create another array variable to hold the new items' quantities:
// I imagine these are your existing variables from your sample code
$tallesTotalesC = array('XL','M','XL','S');
$cantidadesTotalesC = array(5,2,4,7);
$uniqueTallesTotalesC = array_unique($tallesTotalesC);
// This will reset the indexes of the unique items array
$uniqueTallesTotalesC = array_values($uniqueTallesTotalesC);
// init a new quantities array with zeros
$uniqueCantidadesTotales = array_fill(0, count($uniqueTallesTotalesC), 0);
if (count($uniqueTallesTotalesC) == count($tallesTotalesC)) {
// all items are unique so no need to loop through and sum the quantities
$uniqueCantidadesTotales = $cantidadesTotalesC;
} else {
foreach($uniqueTallesTotalesC as $newIndex => $item) {
// get all indexes of the item in the old array
$oldIndexes = array_keys($tallesTotalesC, $item);
// for each of the index, get the sum the old quantity to the new quantity
foreach($oldIndexes as $oldIndex) {
$uniqueCantidadesTotales[$newIndex] += $cantidadesTotalesC[$oldIndex];
}
}
}
Hope it helps!