numpy.tri

numpy.tri(N, M=None, k=0, dtype=<class 'float'>) [source]

An array with ones at and below the given diagonal and zeros elsewhere.

Parameters:	N : int Number of rows in the array. M : int, optional Number of columns in the array. By default, M is taken equal to N. k : int, optional The sub-diagonal at and below which the array is filled. k = 0 is the main diagonal, while k < 0 is below it, and k > 0 is above. The default is 0. dtype : dtype, optional Data type of the returned array. The default is float.
Returns:	tri : ndarray of shape (N, M) Array with its lower triangle filled with ones and zero elsewhere; in other words T[i,j] == 1 for i <= j + k, 0 otherwise.

Examples

>>> np.tri(3, 5, 2, dtype=int)
array([[1, 1, 1, 0, 0],
       [1, 1, 1, 1, 0],
       [1, 1, 1, 1, 1]])

>>> np.tri(3, 5, -1)
array([[ 0.,  0.,  0.,  0.,  0.],
       [ 1.,  0.,  0.,  0.,  0.],
       [ 1.,  1.,  0.,  0.,  0.]])