tril

Returns an array with all elements above the k-th diagonal set to zero.

Parameters:

Name	Type	Description	Default
x	COO	The input array.	required
k	int	The diagonal above which elements are set to zero. The default is zero, which corresponds to the main diagonal.	0

Returns:

Type	Description
COO	The output lower-triangular matrix.

Raises:

Type	Description
ValueError	If x doesn't have zero fill-values.

See Also

• numpy.tril : NumPy equivalent function

Source code in sparse/numba_backend/_coo/common.py

def tril(x, k=0):
    """
    Returns an array with all elements above the k-th diagonal set to zero.

    Parameters
    ----------
    x : COO
        The input array.
    k : int, optional
        The diagonal above which elements are set to zero. The default is
        zero, which corresponds to the main diagonal.

    Returns
    -------
    COO
        The output lower-triangular matrix.

    Raises
    ------
    ValueError
        If `x` doesn't have zero fill-values.

    See Also
    --------
    - [`numpy.tril`][] : NumPy equivalent function
    """
    from .core import COO

    check_zero_fill_value(x)

    if not x.ndim >= 2:
        raise NotImplementedError("sparse.tril is not implemented for scalars or 1-D arrays.")

    mask = x.coords[-2] + k >= x.coords[-1]

    coords = x.coords[:, mask]
    data = x.data[mask]

    return COO(coords, data, shape=x.shape, has_duplicates=False, sorted=True)