weighted-lottery-php

weighted-lottery-php provides a not equality shuffle function. Determine is based on each choice's proportion of the total weight.

Installation

To install weighted-lottery-php with Composer, just add the following to your composer.json file:

// composer.json
{
    "require-dev": {
        "ksk88/weighted-lottery-php": "dev-master"
    }
}

Then, you can install the new dependencies by running Composer’s update command from the directory where your composer.json file is located:

# install
$ php composer.phar install --dev
# update
$ php composer.phar update ksk88/weighted-lottery-php --dev

# or you can simply execute composer command if you set it to
# your PATH environment variable
$ composer install --dev
$ composer update ksk88/weighted-lottery-php --dev

You can see this library on Packagist.

Composer installs autoloader at ./vendor/autoloader.php. If you use weighted-lottery-php in your php script, add:

require_once 'vendor/autoload.php';

If you use Symfony2, autoloader has to be detected automatically.

Or you can use git clone command:

# HTTP
$ git clone https://github.com/ksk88/weighted-lottery-php.git
# SSH
$ git clone git@github.com:ksk88/weighted-lottery-php.git

Example

<?php
require_once './vendor/autoload.php';
use ksk88\WeightedLotteryPhp\Lot;

$tickets = array(
    array('weight' => 1,  'label' => 'super_rare'),
    array('weight' => 5,  'label' => 'rare'),
    array('weight' => 94, 'label' => 'normal'),
);

$lot = new Lot();
$winners = $lot->pickFromWeightedLottery($tickets);
$winner = reset($winners);

echo $winner['label'];
# super_rare (1%)
# rare       (5%)
# normal     (94%)

Counting Result of Running 10000 times

[1] Create test function. (test.php)

<?php
require_once './vendor/autoload.php';
use ksk88\WeightedLotteryPhp\Lot;

class Draw
{
    public function exec()
    {
        $results = array();

        for ($i = 0; $i < 10000; $i++) {

            // Lottery
            $winner = $this->pick();

            // Count
            $count = 0;
            $label = $winner['label'];
            if (array_key_exists($label, $results)) {
                $count = $results[$label];
            }
            $results[$label] = $count + 1;

        }

        var_export($results);
    }

    private function pick()
    {
        $tickets = array(
            array('weight' => 1,  'label' => 'super_rare'),
            array('weight' => 5,  'label' => 'rare'),
            array('weight' => 50, 'label' => 'normal_1'),
            array('weight' => 50, 'label' => 'normal_2'),
            array('weight' => 50, 'label' => 'normal_3'),
            array('weight' => 50, 'label' => 'normal_4'),
            array('weight' => 50, 'label' => 'normal_5'),
        );

        $lot = new Lot();
        $num_picked = 1;
        $winners = $lot->pickFromWeightedLottery($tickets, $num_picked);

        $winner = reset($winners);

        return $winner;
    }
}

$draw = new Draw();
$draw->exec();

[2] Execute test.php

# execute
$ php test.php
array (
  'super_rare' => 46,
  'rare'       => 200,
  'normal_1'   => 1962,
  'normal_2'   => 1986,
  'normal_3'   => 1990,
  'normal_4'   => 1915,
  'normal_5'   => 1901,
)

[3] Summary count

LABEL	WEIGHT	COUNT
super_rare	1	46
rare	5	200
normal_1	50	1,962
normal_2	50	1,986
normal_3	50	1,990
normal_4	50	1,915
normal_5	50	1,901

Result is random, but based on each choice's proportion of the total weight.

Options

The library has several options. You can easily manipulate your array using options.

• weight_gradient

• Difference frequency of occurrence between the top and bottom.

• So when set '1', the function will operate as normal shuffle.

• Default is null.

• use_order_as_weight

• Use order as the weight of lottery.

• Default is false.

• name_weight_source

• Weight is taken by this name as key.

• Default is 'weight'.

• threshold_conditions

• Cut back tickets by any conditions.

• Default is null.

• name_id

• Use when exclude tickets.

• Default is 'ticket_id'.

• excluded_tickets

• Exclude tickets by ID.

• ID is taken on the basis of 'name_id' as key.

• Default is array().

Usage

• option_usage.php

<?php
require_once './vendor/autoload.php';
use ksk88\WeightedLotteryPhp\Lot;

$results = summary();
ksort($results);
var_dump($results);

function draw() {
    $tickets = array(
        array('rank' => 1),
        array('rank' => 2),
        array('rank' => 3),
        array('rank' => 4),
        array('rank' => 5),
        array('rank' => 6),
        array('rank' => 7),
        array('rank' => 8),
        array('rank' => 9),
        array('rank' => 10),    // Removed by option
    );

    $setting = array(
        'weight_gradient' => 2,
        'use_order_as_weight' => true,
        'threshold_conditions' => array(
            array('name' => 'rank', 'val' => 9,  'sign' => 'lesser_or_equal'),
        ),
    );

    $lot = new Lot();
    $num_picked = 1;
    $winners = $lot->pickFromWeightedLottery($tickets, $num_picked, $setting);

    $winner = reset($winners);
    return $winner;
}

function summary() {
    $results = array();
    for ($i = 0; $i < 10000; $i++) {

        // Lottery
        $winner = draw();

        // Count
        $count = 0;
        $label = $winner['rank'];
        if (array_key_exists($label, $results)) {
            $count = $results[$label];
        }
        $results[$label] = $count + 1;
    }
    return $results;
}

• Result

RANK	COUNT
1	1,492
2	1,398
3	1,318
4	1,189
5	1,070
6	1,038
7	939
8	829
9	727
10	*Removed by option

The difference frequency of occurrence between the top and bottom is roughly doubled by options.