code: def periodogram(self):
          
          from .periodogram import speriodogram
          psd = speriodogram(self.data, window=self.window, sampling=self.sampling,
                               NFFT=self.NFFT, scale_by_freq=self.scale_by_freq,
                               detrend=self.detrend)
          self.psd = psd
docs: An alias to :class:`~spectrum.periodogram.Periodogram`
  
          The parameters are extracted from the attributes. Relevant attributes
          ares :attr:`window`, attr:`sampling`, attr:`NFFT`, attr:`scale_by_freq`,
          :attr:`detrend`.
  
          .. plot::
              :width: 80%
              :include-source:
  
              from spectrum import datasets
              from spectrum import FourierSpectrum
              s = FourierSpectrum(datasets.data_cosine(), sampling=1024, NFFT=512)
              s.periodogram()
              s.plot()