README

ProbabilityChecker

Pretty simple probability implementation that can be used for A/B testing. If you have some feature that you want to run on 20% of the requests. This is right tool for you as you do not need to define how many requests there will be in total.

If you provide 0 as a parameter, it will always return false, if you provide 100, it will always return true. Everything in between will be around the number you provided.

Note: This method is not exact but approximation, so if you want 20%, you will get 21%, 23% maybe 18%, but at the end it will be around 20% (the greater number of request, more accurate will be the percentage).

Installation

This library can be installed via composer:

composer require robier/probability-checker

Sample usage

<?php

$probability = new \Robier\ProbabilityChecker(30);

$skipped = 0;
$executed = 0;
for($i = 0; $i < 1000000; $i++) {
    if ($probability->roll()) {
        $executed++;
    } else {
    	$skipped++;
    }
}

$percentageAtTheEndSkipped = round($skipped / ($executed + $skipped), 6) * 100;
$percentageAtTheEndExecuted = round(100 - $percentageAtTheEndSkipped, 6);

echo "Executed $executed and Skipped $skipped \n";
echo "Executed $percentageAtTheEndExecuted% and Skipped $percentageAtTheEndSkipped%";

1st run

Skipped 699978 and Executed 300022 
Skipped 69.9978% and Executed 30.0022%

2nd run

Skipped 699813 and Executed 300187 
Skipped 69.9813% and Executed 30.0187%

3rd run

Skipped 700351 and Executed 299649 
Skipped 70.0351% and Executed 29.9649%

From this you can see that the percentage is not exact, but it is around 30% as we defined.

Methods

We have few methods in the class:

Name	Description
roll()	Like rolling the dice, depending on provided percentage it will be true or false
isCertian()	If percentage is 100 or more, this method will return true
isImpossible()	If percentage is 0 or less, this method will return true
isPossible()	If percentage is between 0 and 100 (both excluded), this method will return true
::always()	Factory method, that will create new instance with 100%
::never()	Factory method, that will create new instance with 0%

Local development

To run tests locally you can use provided docker setup. Just run:

docker/build

to build the image and then run:

docker/run composer test

to run the tests. If you want to run tests with coverage, you can run:

docker/run composer test:coverage

robier / probability-checker

Maintainers

Details