Choose a variation from a weighted experiment

experiment.php

<?php

/**
 * Choose a variation from a weighted experiment
 * This can be used in A/B testings, in case you need to take a sample of users and apply certain feature on them
 */
function getRandomVariation(array $experiment): string
{
    $weightedVariations = [];

    foreach ($experiment as $variation => $percentage) {
        for ($i = 0; $i < $percentage; $i++) {
            $weightedVariations[] = $variation;
        }
    }

    $randomKey = mt_rand(0, count($weightedVariations) - 1);

    return $weightedVariations[$randomKey];
}

// Example usage
// To distribute the experiment in a percentage values, make sure that sum of all variations equals to 100
$experiment = [
    'original' => 50,
    'V1' => 20,
    'V2' => 30,
];

// Select one variation from the experiment
$variation = getRandomVariation($experiment);