Generating random results by weight in PHP?

Question

I know how to generate a random number in PHP but lets say I want a random number between 1-10 but I want more 3,4,5\'s then 8,9,10\'s. How is this possible? I would post wh

Answer 1

This tutorial walks you through it, in PHP, with multiple cut and paste solutions. Note that this routine is slightly modified from what you'll find on that page, as a result of the comment below.

A function taken from the post:

/**
 * weighted_random_simple()
 * Pick a random item based on weights.
 *
 * @param array $values Array of elements to choose from 
 * @param array $weights An array of weights. Weight must be a positive number.
 * @return mixed Selected element.
 */

function weighted_random_simple($values, $weights){ 
    $count = count($values); 
    $i = 0; 
    $n = 0; 
    $num = mt_rand(1, array_sum($weights)); 
    while($i < $count){
        $n += $weights[$i]; 
        if($n >= $num){
            break; 
        }
        $i++; 
    } 
    return $values[$i]; 
}