numpy中tril和triu的简单用法

参考网址： https://www.cnblogs.com/cymwill/p/7857456.html

# https://www.cnblogs.com/cymwill/p/7857456.html

import numpy as np

arr = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]])
print(np.tril(arr, k=-1))  # Lower triangle of an array.

print(np.triu(arr, k=1))  # Upper triangle of an array