def METHOD_NAME(self):
    maxval = -1e12
    minval = 1e12
    for hf, p in zip(self.hfile, self.plot_f):
        self.get_data(hf)
        p.set_data([self.time, self.f])
        maxval = max(maxval, self.f.max())
        minval = min(minval, self.f.min())
    self.sp_f.set_ylim([1.5 * minval, 1.5 * maxval])
    draw()