Lazily Provides summary statistics, also traversable.
/**
* It should return all the stats.
*/
public function testReturnStats()
{
$distribution = new Distribution([10, 20]);
$stats = $distribution->getStats();
foreach (['min', 'max', 'sum', 'stdev', 'mean', 'mode', 'variance', 'rstdev'] as $key) {
$this->assertArrayHasKey($key, $stats);
}
$this->assertEquals(10, $stats['min']);
$this->assertEquals(20, $stats['max']);
}
/**
* Calculate and set the deviation from the mean time for each iteration. If
* the deviation is greater than the rejection threshold, then mark the iteration as
* rejected.
*/
public function computeStats()
{
$this->rejects = [];
$revs = $this->getRevolutions();
if (0 === count($this->iterations)) {
return;
}
$times = $this->getMetricValuesByRev(TimeResult::class, 'net');
$retryThreshold = $this->getSubject()->getRetryThreshold();
$this->stats = new Distribution($times, $this->computedStats);
foreach ($this->iterations as $iteration) {
// deviation is the percentage different of the value from the mean of the set.
if ($this->stats->getMean() > 0) {
$deviation = 100 / $this->stats->getMean() * ($iteration->getResult(TimeResult::class)->getRevTime($iteration->getVariant()->getRevolutions()) - $this->stats->getMean());
} else {
$deviation = 0;
}
// the Z-Value represents the number of standard deviations this
// value is away from the mean.
$revTime = $iteration->getResult(TimeResult::class)->getRevTime($revs);
$zValue = $this->stats->getStdev() ? ($revTime - $this->stats->getMean()) / $this->stats->getStdev() : 0;
if (null !== $retryThreshold) {
if (abs($deviation) >= $retryThreshold) {
$this->rejects[] = $iteration;
}
}
$iteration->setResult(new ComputedResult($zValue, $deviation));
}
$this->computed = true;
}
private function drawIterations(Variant $variant)
{
$subject = $variant->getSubject();
$this->output->write("[2K");
// clear the whole line
$this->output->write(PHP_EOL);
$this->output->write("[2K");
// clear the whole line
$this->output->write("[1A");
$sigma = 2;
$bins = 16;
if ($variant->isComputed()) {
$times = $variant->getMetricValues(ComputedResult::class, 'z_value');
$stats = $variant->getStats();
$freqs = Statistics::histogram($times, $bins, -$sigma, $sigma);
} else {
$stats = new Distribution([0]);
$freqs = array_fill(0, $bins + 1, null);
}
$this->output->write(sprintf('#%-2d (σ = %s ) -%sσ [', $subject->getIndex(), $this->timeUnit->format($stats->getStdev()), $sigma));
$this->drawBlocks($freqs, $stats);
$this->output->write(sprintf('] +%sσ <comment>%s</comment>', $sigma, $variant->isComputed() ? $this->formatIterationsShortSummary($variant) : ''));
$this->output->write(PHP_EOL);
}
