如何生成对角矩阵 numpy.diag_python

import numpy as np
a=[1,2,3]
np.diag(a)
Out[4]: 
array([[1, 0, 0],
       [0, 2, 0],
       [0, 0, 3]])

numpy.diag(v,k=0) 

>>> x = np.arange(9).reshape((3,3))
>>> x
array([[0, 1, 2],
       [3, 4, 5],
       [6, 7, 8]])
       
>>> np.diag(x)
array([0, 4, 8])
>>> np.diag(x, k=1)
array([1, 5])
>>> np.diag(x, k=-1)
array([3, 7])
>>> np.diag(np.diag(x))
array([[0, 0, 0],
       [0, 4, 0],
       [0, 0, 8]])