src/Linguistics.php
public function getUniqueWords($string)
    {
        $words = $this->getWords($string);
        $analysis = new FrequencyAnalysis($words);
        $words = $analysis->getKeyValuesByFrequency();

        return array_unique(array_keys($words));
    }
public function getUniqueWords($string)
    {
        $words = $this->getWords($string);
        $analysis = new FrequencyAnalysis($words);
        $words = $analysis->getKeyValuesByFrequency();

        return array_unique(array_keys($words));
    }
Get unique words.

@param string $string

@return array