private String featuresToString(ArrayList<Float> features)
    {
        String result = "";
        int counterUsefulValues = 0;
        for (Float element: features)
        {
            if (element != null && !element.isNaN() && !element.isInfinite())
            {
                NumberFormat format = new DecimalFormat("0.#####");
                result += format.format(element) + ",";
                counterUsefulValues++;
            }
            else
            {
                result += "?,";
            }
            
        }
        if (counterUsefulValues != 0)
        {
            return result;
        }
        else
        {
            return "";
        }
    }