Sometimes you will want to get a random value form an array in a biased random way, that is, you will want certain values to be returned more than others. Here is a function that will generate a single key from an array, with a greater change of a higher value being retrieved.
function biasedRandom($numbers){
$total = 0;
foreach($numbers as $number=>$weight){
$total += $weight;
$distribution[$number] = $total;
};
$rand = mt_rand(0,$total-1);
foreach($distribution as $number=>$weights){
if($rand<$weights){
return $number;
};
};
}This function is used in the following way.
//set up array
$array = array('one'=>100,
'two'=>100,
'three'=>100,
'four'=>500);
// get biased random number
echo biasedRandom($array);The key that is generated the most by the function is four because it has a higher value than the rest and will therefore 'weigh' a lot more.