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

I just released a class to perform weighted sorting easily.

It's based on the same algorithm mentioned in Brad's and Allain's answers, and is optimized for speed, unit-tested for uniform distribution, and supports elements of any PHP type.

Using it is simple. Instantiate it:

$picker = new Brick\Random\RandomPicker();

Then add elements as an array of weighted values (only if your elements are strings or integers):

$picker->addElements([
    'foo' => 25,
    'bar' => 50,
    'baz' => 100
]);

Or use individual calls to addElement(). This method supports any kind of PHP values as elements (strings, numbers, objects, ...), as opposed to the array approach:

$picker->addElement($object1, $weight1);
$picker->addElement($object2, $weight2);

Then get a random element:

$element = $picker->getRandomElement();

The probability of getting one of the elements depends on its associated weight. The only restriction is that weights must be integers.