Multidimensional Array delete duplicated key values with condition - php

Question

I have an Array Like this:
$ratesData = [
1 => [
'id' => 1,
'amount' => 2
],
0 => [
'id' => 1,
'amount' => 1
],
2 => [
'id' => 1,
'amount' => 3
],
3 => [
'id' => 2,
'amount' => 2
]
];
I want to keep the duplicated id arrays with cheapest amount, the result will be like this:
[
0 => [
'id' => 1,
'amount' => 1
],
1 => [
'id' => 2,
'amount' => 2
]
]
I have a code that works with this problem, but I'm searching an elegant way to accomplish this without all this loops:
foreach($ratesData as $firstLoopKey => $firstLoopValue) {
foreach($ratesData as $secondLoopKey => $secondLoopValue) {
if($firstLoopValue['id'] === $secondLoopValue['id'] && $firstLoopKey != $secondLoopKey ) {
if ($ratesData[$secondLoopKey]['total_amount'] > $ratesData[$firstLoopKey]['total_amount']) {
$deleteElements[] = $secondLoopKey;
}
}
}
}
if (isset($deleteElements)) {
foreach ($deleteElements as $element) {
unset($ratesData[$element]);
}
}
$ratesData = array_values($ratesData);
return $ratesData;

Answer 1

You can sort by amount descending and then extract the array indexing by id which will eliminate the duplicates with the lowest amount overwriting the higher:
array_multisort(array_column($ratesData, 'amount'), SORT_DESC, $ratesData);
$ratesData = array_column($ratesData, null, 'id');
Yields:
Array
(
[1] => Array
(
[id] => 1
[amount] => 1
)
[2] => Array
(
[id] => 2
[amount] => 2
)
)
I always like having the key the same as a unique id to make array access/sorting easier, but you can re-index if needed:
$ratesData = array_values($ratesData);

Answer 2

Some simple solution:
// your source array
$ratesData = [];
// result array
$filtered = [];
foreach ($ratesData as $v) {
$id = $v['id'];
// if this is `$id`, which is not in `$filtered` yet
// or value of `$filtered[$id]['amount']` is greater then current `$v`
// then replace `$filtered[$id]` with current `$v`
if (!isset($filtered[$id]) || $filtered[$id]['amount'] > $v['amount']) {
$filtered[$id] = $v;
}
}
echo'<pre>',print_r(array_values($filtered)),'</pre>';

Answer 3

Another good solution
$uniqueRates = [];
foreach ($ratesData as $rateData) {
$key = $rateData['id'];
if (!\array_key_exists($key, $uniqueRates) ||
$rateData['total_amount'] < $uniqueRates[$key]['total_amount']
) {
$uniqueRates[$key] = $rateData;
}
}
return array_values($uniqueRates);