I have a pivot table in Dashboard and i want to add a column where i'll show the difference between current and previous period. Is this possible? Do i have to use pivot2D process like your example below or something else? https://www.koolreport.com/docs/pivot/pivot2D_process/

For example i have tried the code below but it doesn't work.

class myPivot extends PivotTable
{
    protected function process()
    {
        return [
,,,
            "computations" => array(
				"yearlyDifference" => "{2023-10} - {2023-09}",
				"monthlyDifference" => function($aggRow) {
				return ($aggRow['2023 -||- 11 -||- Amount - sum'] ) - ($aggRow['2023-10 -||- Amount - sum'] ?? 0);
				},
....

I also tried this code without success:

    protected function display()
    {
        return [
...
            'map' => array(
        "{value}" => function($row) {
            $row["2023 -||- 11 -||- percentage change"] = 
                100 * $row["2023 -||- 11 -||- Amount - sum"] / $row["2023 -||- 10 -||- Amount - sum"];
            return $row;
        }