Weighted "Spin the Prize Wheel" function

weighted-spin.php

<?php
function lottery_spin_the_wheel() {

    //Form is key (reward as string) value (frequency as int) 
    $rewards_master = array(
        '1 bonus token'=>25,
        '5-album mini themed list'=>20,
        'Album on demand'=>20,
        'Trade 1 token for 2 tokens of your choice'=>15,
        'Top-off overload +5 on Wednesday'=>10,
        'Book recommendation'=>10,
        'Described movie recommendation'=>10,
        'Top-off overload +10 on Wednesday'=>8,
        '3 albums on demand'=>8,
        '2 bonus tokens'=>8,
        '1 surprise item'=>8,
        'Snack delivery'=>8,
        'Trade 3 tokens for 5 tokens of your choice'=>8,
        '10-album themed list'=>5,
        'Ice cream date'=>3,
        'Home-cooked meal of your choice'=>3,
        'Themed list sample platter: 3 5-album themed lists'=>3,
        '3 surprise items'=>3,
        'Instant top-off on any day'=>3,
        'Dinner date'=>3,
        '5 bonus tokens'=>2,
        'Themed list party pack: 2 10-album themed lists'=>1,
        '5 surprise items'=>1,
        '25-album themed list'=>1
    );

      $rewards_choices = array();

      foreach ($rewards_master as $reward => $frequency) {        
        $rewards_choices = array_merge($rewards_choices, array_fill(0, $frequency, "$reward"));
      }

      shuffle($rewards_choices);

      $reward = ucwords($rewards_choices[0]);

      return $reward;
}

Suggestion: I have a google sheet to build out the $rewards_master array. One column is frequency, one is reward string, and I use CONCATENATE() to build out the array elements, as well as calculate percentages.

In the above, the most frequent item (1 bonus token) happens roughly 13.4% of the time, while the least frequent (value of 1) happen 0.54% of the time.