code: def infer_spectra(self, ds):
          
          lvec_all = _get_lvec(ds.test_label_vals, self.pivots, self.scales, derivs=False)
          self.model_spectra = np.dot(lvec_all, self.coeffs.T)
docs: After inferring labels for the test spectra,
          infer the model spectra and update the dataset
          model_spectra attribute.
          
          Parameters
          ----------
          ds: Dataset object