public function testNextSample()
{
$sampler = new GaussianSampler(Random::create());
$data = [];
for ($i = 0; $i < 50000; $i++) {
$data[] = $sampler->nextSample();
}
$c = count($data);
// Average
$avg = array_sum($data) / $c;
$this->assertTrue(abs($avg) < 0.02);
// Median
sort($data);
$median = $data[(int) ($c / 2)];
$this->assertTrue(abs($median) < 0.02);
// Mode
$stats = [];
foreach ($data as $num) {
$k = (string) (0.0 + sprintf('%.1f', $num));
if (!isset($stats[$k])) {
$stats[$k] = 0;
}
$stats[$k]++;
}
arsort($stats);
$key = (double) key($stats);
$this->assertTrue($key >= -0.2 && $key <= 0.2);
$this->assertTrue($stats['0'] > $stats['3']);
$a1 = $stats['0.1'] + $stats['-0.1'] + $stats['0.2'] + $stats['-0.2'] + $stats['0.3'] + $stats['-0.3'];
$a2 = $stats['0.4'] + $stats['-0.4'] + $stats['0.5'] + $stats['-0.5'] + $stats['0.6'] + $stats['-0.6'];
$this->assertTrue($a1 > $a2);
// Simple probability distribution test
$stats = [];
foreach ($data as $num) {
$k = ceil(abs($num));
if (!isset($stats[$k])) {
$stats[$k] = 0;
}
$stats[$k]++;
}
$k = 100 / $c;
$p1 = round($k * $stats[1]);
$p2 = round($k * ($stats[2] + $stats[1]));
$p3 = round($k * ($stats[3] + $stats[2] + $stats[1]));
// 68% of the data should be within one standard deviation
$this->assertTrue($p1 >= 67 && $p1 <= 69);
// 95% of the data should be within two standard deviations
$this->assertTrue($p2 >= 94 && $p1 <= 96);
// 99% of the data should be within three standard deviations
$this->assertTrue($p3 >= 98);
}
/**
* @expectedException \Savvot\Random\RandException
*/
public function testBadStateClassException()
{
$rnd = Random::createFromState(['class' => __CLASS__]);
}
