如何在 Python 中将列或行矩阵转换为对角矩阵? [英] How to convert a column or row matrix to a diagonal matrix in Python?

问题描述

我有一个行向量 A，A = [a1 a2 a3 ..... an] 我想创建一个对角矩阵，B = diag(a1, a2, a3, ....., an) 与此行向量的元素.这如何在 Python 中完成?

I have a row vector A, A = [a1 a2 a3 ..... an] and I would like to create a diagonal matrix, B = diag(a1, a2, a3, ....., an) with the elements of this row vector. How can this be done in Python?

更新

这是说明问题的代码:

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

这段代码的输出是[1]，但我想要的输出是:

the output of this code is [1], but my desired output is:

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

推荐答案

您可以使用 diag 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]]

如果你有一个行向量，你可以这样做:

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)

结果又来了:

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

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