/
Statistics.php
48 lines (39 loc) · 1.06 KB
/
Statistics.php
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<?php
namespace oSoc\Smartflanders\Helpers;
class Statistics
{
private $data;
private $sorted = false;
public function __construct(array $data) {
$this->data = $data;
}
public function mean() {
return array_sum($this->data) / count($this->data);
}
public function median() {
return $this->percentile(0.50);
}
public function percentile($percent) {
if (!$this->sorted) {
sort($this->data);
$this->sorted = true;
}
$index = ceil($percent * count($this->data)) - 1;
$value = $this->data[$index];
if (count($this->data)%2 === 0) {
$value = ($value + $this->data[$index-1])/2;
}
return $value;
}
public function variance() {
$mean = $this->mean();
$numerator = 0;
foreach($this->data as $d) {
$numerator += ($d-$mean)**2;
}
if (count($this->data) > 1) {
return $numerator/(count($this->data)-1);
}
return $numerator/count($this->data);
}
}