numpy.tril¶

numpy.tril(m,k=0)[source]¶

Lower triangle of an array.

Return a copy of an array with elements above thek-th diagonal zeroed.

Parameters:	m:array_like, shape (M, N) Input array. k:int, optional Diagonal above which to zero elements.k = 0 (the default) is themain diagonal,k < 0 is below it andk > 0 is above.
Returns:	tril:ndarray, shape (M, N) Lower triangle ofm, of same shape and data-type asm.

See also

triu

same thing, only for the upper triangle

Examples

>>>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]])