Title: Getting The Diagonal Of A Matrix
Slug: getting_the_diagonal_of_a_matrix
Summary: How to get the diagonal of a matrix in Python.
Date: 2017-09-02 12:00
Category: Machine Learning
Tags: Vectors Matrices Arrays
Authors: Chris Albon

Preliminaries



In [1]:

    
# Load library
import numpy as np

Create Matrix



In [2]:

    
# Create matrix
matrix = np.array([[1, 2, 3],
                   [4, 5, 6],
                   [7, 8, 9]])

Get The Diagonal



In [3]:

    
# Return diagonal elements
matrix.diagonal()









    Out[3]:





array([1, 5, 9])

Calculate The Trace



In [4]:

    
# Calculate the tracre of the matrix
matrix.diagonal().sum()









    Out[4]:





15