1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
| #!/usr/bin/env python3
# -*- coding: utf-8 -*-
# 2019-10-25 不更新时间了
# numpy 学习笔记
# icenaive
# 参考： https://github.com/lijin-THU/notes-python
# 仅供个人学习使用
#
# 8. 对角线
import numpy as np
a = np.array([11, 21, 31, 12, 22, 32, 13, 23, 33])
a.shape = 3, 3
print(a)
# 查看对角线元素
print(a.diagonal())
# 可以添加偏移来查看对角线，正数代表右移 负数代表右移
print(a.diagonal(offset = 1))
print(a.diagonal(offset = -1))
# 可以使用花式索引来的到对角线
i = [0, 1, 2]
print(a[i, i])
# 更新对角线的值
a[i, i] = 2
print(a)
# 修改次对角线的值
i = np.array([0, 1])
a[i, i + 1] = 1
print(a)
a[i + 1, i] = 3
print(a)
|