numpy.triu()

Upper triangle of an array.

Return a copy of a matrix with the elements below the k-th diagonal zeroed.

Please refer to the documentation for tril for further details.

Examples

>>> np.triu([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], -1)
array([[ 1,  2,  3],
       [ 4,  5,  6],
       [ 0,  8,  9],
       [ 0,  0, 12]])