If wavelength info is not passed in the SpectralLibrary constructor header argument, the following exception is raised:
----> 1 s.save('mylib.json')
~/src/spectral/spectral/io/envi.py in save(self, fileBaseName, description)
980 meta['samples'] = len(self.bands.centers)
981 else:
--> 982 meta['samples'] = len(self.spectra.shape[0])
983 meta['lines'] = self.spectra.shape[0]
984 meta['bands'] = 1
TypeError: object of type 'int' has no len()
Line 982 should actually be
meta['samples'] = self.spectra.shape[1]