Readability\Readability::getLinkDensity PHP Method

    public function getLinkDensity($e, $excludeExternal = false)
    {
        $links = $e->getElementsByTagName('a');
        $textLength = mb_strlen($this->getInnerText($e, true, true));
        $linkLength = 0;
        for ($dRe = $this->domainRegExp, $i = 0, $il = $links->length; $i < $il; ++$i) {
            if ($excludeExternal && $dRe && !preg_match($dRe, $links->item($i)->getAttribute('href'))) {
                continue;
            }
            $linkLength += mb_strlen($this->getInnerText($links->item($i)));
        }
        if ($textLength > 0 && $linkLength > 0) {
            return $linkLength / $textLength;
        }
        return 0;
    }