您可以使用诊断方法:

import numpy as np

a = np.array([1,2,3,4])
d = np.diag(a)
# or simpler: d = np.diag([1,2,3,4])

print(d)

结果:

[[1 0 0 0]
 [0 2 0 0]
 [0 0 3 0]
 [0 0 0 4]]

如果您有行向量，则可以执行以下操作:

If you have a row vector, you can do this:

a = np.array([[1, 2, 3, 4]])
d = np.diag(a[0])

结果:

[[1 0 0 0]
 [0 2 0 0]
 [0 0 3 0]
 [0 0 0 4]]

对于问题中的给定矩阵:

For the given matrix in the question:

import numpy as np
a = np.matrix([1,2,3,4])
d = np.diag(a.A1)
print (d)

结果再次是:

[[1 0 0 0]
 [0 2 0 0]
 [0 0 3 0]
 [0 0 0 4]]