NumPy

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
Nint

Number of rows in the array.

Mint, optional

Number of columns in the array. By default, M is taken equal to N.

kint, 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.

dtypedtype, optional

Data type of the returned array. The default is float.

Returns
trindarray of shape (N, M)

Array with its lower triangle filled with ones and zero elsewhere; in other words T[i,j] == 1 for j <= i + 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.]])

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