Vassyli
112 lines
2.8 KiB
PHP
112 lines
2.8 KiB
PHP
<?php
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declare(strict_types=1);
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namespace LotGD\Core;
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/**
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* A collection of random number generators, with various distributions.
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*/
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class DiceBag
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{
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/**
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* Returns true $p percent of the time, where $p is between 0 and 1.
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* @param float $p
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* @return bool True if you are lucky, False if not.
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*/
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public function chance(float $p): bool
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{
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$r = $this->uniform(0., 1.);
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return $r < $p;
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}
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/**
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* Generates a uniformly randomly number between $min and $max.
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* @param float $min
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* @param float $max
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* @return float random number between $min and $max
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*/
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public function uniform(float $min, float $max): float
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{
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return (\mt_rand(0, 100) / 100.0) * ($max - $min) + $min;
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}
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/**
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* Generates a uniformly randomly integer between $min and $max.
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* @param int $min
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* @param int $max
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* @return int random number between $min and $max
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*/
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public function dice(int $min, int $max): int
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{
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if ($min == $max) {
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return $min;
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}
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if ($min > $max) {
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$a = $min;
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$min = $max;
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$max = $a;
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}
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return \mt_rand($min, $max);
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}
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/**
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* Generates a normally distributed random number between $min and $max.
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* @param float $min
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* @param float $max
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* @return float normally distributed random number
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*/
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public function normal(float $min, float $max): float
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{
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if ($min > $max) {
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$tmp = $max;
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$max = $min;
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$min = $tmp;
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} elseif ($min == $max) {
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return $min;
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}
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$mean = ($max - $min) / 2;
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$r = 0;
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do {
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$u1 = \mt_rand() / \mt_getrandmax();
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$u2 = \mt_rand() / \mt_getrandmax();
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$r = \sqrt(-2 * \log($u1)) * \cos(2 * \pi() * $u2) + $mean;
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} while ($r < $min || $r > $max);
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return $r;
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}
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/**
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* This function has uniform distribution except for the extreme values, which are
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* half as likely to happen.
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* The code for this function was taken from LotGD in version 0.9.7.
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* @author MightyE, JT
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* @param int|null $min
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* @param int|null $max
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* @return int
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*/
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public function pseudoBell(int $min = null, int $max = null): int
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{
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if (\is_null($min)) {
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return \mt_rand();
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}
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$min *= 1000;
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if (\is_null($max)) {
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return (int)\round(\mt_rand($min) / 1000, 0);
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}
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$max *= 1000;
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if ($min === $max) {
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return (int)\round($min / 1000, 0);
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} elseif ($min < $max) {
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return (int)\round(\mt_rand($min, $max) / 1000, 0);
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}
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return (int)\round(\mt_rand($max, $min) / 1000, 0);
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}
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}
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