1import numpy as np 

2 

3from ase.dft.dos import DOS 

4from ase.dft.kpoints import monkhorst_pack 

5 

6__all__ = ['DOS', 'monkhorst_pack'] 

7 

8 

9def get_distribution_moment(x, y, order=0): 

10 """Return the moment of nth order of distribution. 

11 

12 1st and 2nd order moments of a band correspond to the band's 

13 center and width respectively. 

14 

15 For integration, the trapezoid rule is used. 

16 """ 

17 

18 x = np.asarray(x) 

19 y = np.asarray(y) 

20 

21 if order == 0: 

22 return np.trapz(y, x) 

23 elif isinstance(order, int): 

24 return np.trapz(x**order * y, x) / np.trapz(y, x) 

25 elif hasattr(order, '__iter__'): 

26 return [get_distribution_moment(x, y, n) for n in order] 

27 else: 

28 raise ValueError('Illegal order: %s' % order)