README

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.

ksk88 / weighted-lottery-php

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