numpy.tril — NumPy v2.2 Manual (original) (raw)

numpy.tril(m, k=0)[source]#

Lower triangle of an array.

Return a copy of an array with elements above the _k_-th diagonal zeroed. For arrays with ndim exceeding 2, tril will apply to the final two axes.

Parameters:

marray_like, shape (…, M, N)

Input array.

kint, optional

Diagonal above which to zero elements. k = 0 (the default) is the main diagonal, k < 0_ is below it and _k > 0 is above.

Returns:

trilndarray, shape (…, M, N)

Lower triangle of m, of same shape and data-type as m.

See also

triu

same thing, only for the upper triangle

Examples

import numpy as np np.tril([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], -1) array([[ 0, 0, 0], [ 4, 0, 0], [ 7, 8, 0], [10, 11, 12]])

np.tril(np.arange(345).reshape(3, 4, 5)) array([[[ 0, 0, 0, 0, 0], [ 5, 6, 0, 0, 0], [10, 11, 12, 0, 0], [15, 16, 17, 18, 0]], [[20, 0, 0, 0, 0], [25, 26, 0, 0, 0], [30, 31, 32, 0, 0], [35, 36, 37, 38, 0]], [[40, 0, 0, 0, 0], [45, 46, 0, 0, 0], [50, 51, 52, 0, 0], [55, 56, 57, 58, 0]]])