numpy.tril() in Python

numpy.tril() in Python

The tril() function of Python numpy class returns a copy of an array with the elements above the k-th diagonal zeroed.

Syntax

numpy.tril(m, k=0)

Parameter

a: It represents the input array

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

Return

This function returns the Lower triangle of the parameter ‘a’ while having the same shape and data-type as ‘a’.

Example 1

# Python Program explaining
# numpy.tril() function
import numpy as np
# string input
mat = np.matrix([[11, 29, 33], 
                 [93 ,44, 93], 
                 [55, 34, 56]])
print("The Diagonal elements: \n", np.tril(mat))
print("\nThe Diagonal above the main Diagonal elements: \n", np.tril(mat, 1))
print("\nThe Diagonal elements: \n", np.tril(mat, -1))

Output

The Diagonal elements:
[[11  0  0]
[93 44  0]
[55 34 56]]
The Diagonal above the main Diagonal elements:
[[11 29  0]
[93 44 93]
[55 34 56]]
The Diagonal elements:
[[ 0  0  0]
[93  0  0]
[55 34  0]]