numpy.diag() in Python

numpy.diag(a, k=0) : Extracts and construct a diagonal array 
Parameters : 

a : array_like 
k : [int, optional, 0 by default]
          Diagonal we require; k>0 means diagonal above main diagonal or vice versa.

Returns : 

ndarray

Python

# 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))

Output : 

Main Diagonal elements : 
 [  1 434  56] 

Diagonal above main diagonal : 
 [21  3] 

Diagonal below main diagonal : 
 [63 54]

References : 
https://docs.scipy.org/doc/numpy/reference/generated/numpy.diagflat.html#numpy.diagflat
Note : 
These NumPy-Python programs won’t run on online IDE’s, so run them on your systems to explore them 
.