Function setitem_array

dask/array/slicing.py:1464–2027

Master function for array assignment. This function, that is intended to be called by `Array.__setitem__`, creates a new dask that assigns values to each block that is touched by the indices, leaving other blocks unchanged. Each block that overlaps the indices is assigned from

(out_name, array, indices, value)

def setitem_array(out_name, array, indices, value):
    """Master function for array assignment.

    This function, that is intended to be called by
    `Array.__setitem__`, creates a new dask that assigns values to
    each block that is touched by the indices, leaving other blocks
    unchanged.

    Each block that overlaps the indices is assigned from the
    appropriate part of the assignment value. The dasks of these value
    parts are included in the output dask dictionary, as are the dasks
    of any 1-d dask array indices. This ensures that the dask array
    assignment value and any dask array indices are not computed until
    the `Array.__setitem__` operation is computed.

    The part of the assignment value applies to block is created as a
    "getitem" slice of the full assignment value.

    Parameters
    ----------
    out_name : `str`
        The dask variable output name.
    array : dask array
        The dask array that is being assigned to.
    indices : numpy-style indices
        Indices to array defining the elements to be assigned.
    value : dask array
        The assignment value, i.e. the values which will be assigned
        to elements of array.

    Returns
    -------
    dsk : `dict`
        A dictionary where the keys are new unique tokens for each
        block of the form

            (out_name, dim_index[, dim_index[, ...]])

       and the values are either

            (key,)

        or

            (setitem, key, v_key, block_indices)

        where key is an existing top-level dask key of array.

        The first case occurs when the block represented by key does
        not overlap the indices.

        The second case occurs when the block represented by key does
        overlap the indices. setitem is the chunk assignment function;
        v_key is the dask key of the part of the assignment value
        that corresponds to the block; and block_indices are the
        assignment indices that apply to the block.

        The dictionary also includes any additional key/value pairs