qmegas/php-rand-custom-distribution

Random number generator with custom distribution

1.0.1 2022-06-30 19:45 UTC

Requires

• php: >=7.0

MIT

• Qmegas

• generator
• random
• custom distribution

README

Standard PHP functions like rand or mt_rand generate random numbers with normal distribution, however sometimes it required to generate random numbers with different distribution, for example binomial distribution.

Installation

composer require qmegas/php-rand-custom-distribution

Requirements

PHP >= 7.0

Simple Example

$generator = new \Qmegas\RandomGenerator(50, 150, function(float $i) {
	return $i * 100;
});
echo $generator->getNumber();

Class constractor receives 3 arguments: low-high bounds of generated numbers and distribution function. Distribution function receives float argument between 0 and 1 and should return some integer value >= 0, see additional examples for better understanding.

Some Additional Examples

Normal Distribution	$generator = new \Qmegas\RandomGenerator($min, $max, function() { return 1; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return $i * 100; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return (1 - $i) * 100; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return (1 - $i) * 200 * $i; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return (2 * (1 - $i) * ($i ** 0.5) + ($i ** 2)) * 100; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return ($i ** 3) * 100; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return (3 * ((1 - $i) ** 2) * $i + ($i ** 3)) * 100; });
	$generator = new \Qmegas\RandomGenerator($min, $max, function(float $i) { return (1 / (1 + exp(-10 * ($i - 0.5)))) * 100; });