numpy.diag() in Python

numpy.diag() in Python

The diag() function of Python numpy class extracts and construct a diagonal array.

Syntax

numpy.diag(v, k=0)

Parameter

a: It represents the array_like.

k: It represents the diagonal value that we require. It is an optional parameter and its default value is 0. If k>0, the diagonal is above the main diagonal or vice versa.

Return

This function returns the extracted diagonal or constructed diagonal array.

Example 1

# Python Programming explaining
# numpy.diag() function
import numpy as np
# matrix creation by array input
num = np.matrix([[11, 121, 130], 
                 [613 ,34, 13], 
                 [514, 50, 16]])
print("Main Diagnol elements : \n", np.diag(num))
print("\nDiagnol elements above main diagnol : \n", np.diag(num, 1) )
print("\nDiagnol elements below main diagnol : \n", np.diag(num, -1))

Output

Main Diagnol elements :
[11 34 16]
Diagnol elements above main diagnol :
[121  13]
Diagnol elements below main diagnol :
[613  50]