Function normalize_index

dask/array/slicing.py:800–866

Normalize slicing indexes 1. Replaces ellipses with many full slices 2. Adds full slices to end of index 3. Checks bounding conditions 4. Replace multidimensional numpy arrays with dask arrays 5. Replaces numpy arrays with lists 6. Posify's integers and lists 7. N

(idx, shape)

def normalize_index(idx, shape):
    """Normalize slicing indexes

    1.  Replaces ellipses with many full slices
    2.  Adds full slices to end of index
    3.  Checks bounding conditions
    4.  Replace multidimensional numpy arrays with dask arrays
    5.  Replaces numpy arrays with lists
    6.  Posify's integers and lists
    7.  Normalizes slices to canonical form

    Examples
    --------
    >>> normalize_index(1, (10,))
    (1,)
    >>> normalize_index(-1, (10,))
    (9,)
    >>> normalize_index([-1], (10,))
    (array([9]),)
    >>> normalize_index(slice(-3, 10, 1), (10,))
    (slice(7, None, None),)
    >>> normalize_index((Ellipsis, None), (10,))
    (slice(None, None, None), None)
    >>> normalize_index(np.array([[True, False], [False, True], [True, True]]), (3, 2))
    (dask.array<array, shape=(3, 2), dtype=bool, chunksize=(3, 2), chunktype=numpy.ndarray>,)
    """
    from dask.array import Array, from_array

    if not isinstance(idx, tuple):
        idx = (idx,)

    # if a > 1D numpy.array is provided, cast it to a dask array
    if len(idx) > 0 and len(shape) > 1:
        i = idx[0]
        if is_arraylike(i) and not isinstance(i, Array) and i.shape == shape:
            idx = (from_array(i), *idx[1:])

    idx = replace_ellipsis(len(shape), idx)
    n_sliced_dims = 0
    for i in idx:
        if hasattr(i, "ndim") and i.ndim >= 1:
            n_sliced_dims += i.ndim
        elif i is None:
            continue
        else:
            n_sliced_dims += 1

    idx = idx + (slice(None),) * (len(shape) - n_sliced_dims)
    if len([i for i in idx if i is not None]) > len(shape):
        raise IndexError("Too many indices for array")

    none_shape = []
    i = 0
    for ind in idx:
        if ind is not None:
            none_shape.append(shape[i])
            i += 1
        else: