numpy.tril_indices() function | Python

numpy.tril_indices() function return the indices for the lower-triangle of an (n, m) array.

Syntax : numpy.tril_indices(n, k = 0, m = None)
Parameters :
n : [int] The row dimension of the arrays for which the returned indices will be valid.
k : [int, optional] Diagonal offset.
m : [int, optional] The column dimension of the arrays for which the returned arrays will be valid. By default m is taken equal to n.
Return : [tuple of arrays] The indices for the triangle. The returned tuple contains two arrays, each with the indices along one dimension of the array.

Code #1 :

Output :

(array([0, 1, 1, 2, 2, 2]), array([0, 0, 1, 0, 1, 2]))

 
Code #2 :

Output :

(array([0, 0, 0, 1, 1, 1, 2, 2, 2]), array([0, 1, 2, 0, 1, 2, 0, 1, 2]))