def update(self, x_list=list(), y_list=list()):
        """
        update interpolation data
        :param list(float) x_list: x values
        :param list(float) y_list: y values
        """
        if not y_list:
            for x in x_list:
                if x in self.x_list:
                    i = self.x_list.index(float(x))
                    self.x_list.pop(i)
                    self.y_list.pop(i)
        else:
            x_list = map(float, x_list)
            y_list = map(float, y_list)
            data = [(x, y) for x, y in zip(self.x_list, self.y_list) if x not in x_list]
            data.extend(zip(x_list, y_list))
            data = sorted(data)
            self.x_list = [float(x) for (x, y) in data]
            self.y_list = [float(y) for (x, y) in data]
update interpolation data
        :param list(float) x_list: x values
        :param list(float) y_list: y values