where

Select values from either x or y depending on condition. If x and y are not given, returns indices where condition is nonzero.

Performs the equivalent of numpy.where.

Parameters:

Name	Type	Description	Default
condition	SparseArray	The condition based on which to select values from either x or y.	required
x	SparseArray	The array to select values from if condition is nonzero.	None
y	SparseArray	The array to select values from if condition is zero.	None

Returns:

Type	Description
COO	The output array with selected values if x and y are given; else where the array is nonzero.

Raises:

Type	Description
ValueError	If the operation would produce a dense result; or exactly one of x and y are given.

See Also

numpy.where : Equivalent Numpy function.

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

def where(condition, x=None, y=None):
    """
    Select values from either ``x`` or ``y`` depending on ``condition``.
    If ``x`` and ``y`` are not given, returns indices where ``condition``
    is nonzero.

    Performs the equivalent of [`numpy.where`][].

    Parameters
    ----------
    condition : SparseArray
        The condition based on which to select values from
        either ``x`` or ``y``.
    x : SparseArray, optional
        The array to select values from if ``condition`` is nonzero.
    y : SparseArray, optional
        The array to select values from if ``condition`` is zero.

    Returns
    -------
    COO
        The output array with selected values if `x` and `y` are given;
        else where the array is nonzero.

    Raises
    ------
    ValueError
        If the operation would produce a dense result; or exactly one of
        `x` and `y` are given.

    See Also
    --------
    [`numpy.where`][] : Equivalent Numpy function.
    """
    from .._umath import elemwise

    x_given = x is not None
    y_given = y is not None

    if not (x_given or y_given):
        check_zero_fill_value(condition)
        condition = asCOO(condition, name=str(np.where))
        return tuple(condition.coords)

    if x_given != y_given:
        raise ValueError("either both or neither of x and y should be given")

    return elemwise(np.where, condition, x, y)