Python numpy.diag()

numpy.diag(a, k=0):提取并构造一个对角数组
参数 :

a : array_like 
k : [int, optional, 0 by default] 。
          我们需要的对角线；k>0意味着对角线高于主对角线，反之亦然。

返回值 :

ndarray

# Python Programming illustrating
# numpy.diag method
  
import numpy as geek
  
# matrix creation by array input
a = geek.matrix([[1, 21, 30], 
                 [63 ,434, 3], 
                 [54, 54, 56]])
  
print("Main Diagonal elements : \n", geek.diag(a), "\n")
  
print("Diagonal above main diagonal : \n", geek.diag(a, 1), "\n")
  
print("Diagonal below main diagonal : \n", geek.diag(a, -1))

输出 :

Main Diagonal elements : 
 [  1 434  56] 

Diagonal above main diagonal : 
 [21  3] 

Diagonal below main diagonal : 
 [63 54]