Skip to main content
`Ctrl`+`K`

# numpy.tri

numpy.tri(N, M=None, k=0, dtype=<class 'float'>, *, like=None)

  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.

    like array_like, optional

      Reference object to allow the creation of arrays which are not NumPy arrays. If an array-like passed in as `like` supports the `__array_function__` protocol, the result will be defined by it. In this case, it ensures the creation of an array object compatible with that passed in via this argument.

      New in version 1.20.0.

  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 `j <= i + k`, 0 otherwise.

  Examples

      >>> import numpy as np
      >>> np.tri(3, 5, 2, dtype=np.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.]])