Function diff

dask/array/routines.py:575–620

(a, n=1, axis=-1, prepend=None, append=None)

@derived_from(np)
def diff(a, n=1, axis=-1, prepend=None, append=None):
    a = asarray(a)
    n = int(n)
    axis = int(axis)

    if n == 0:
        return a
    if n < 0:
        raise ValueError(f"order must be non-negative but got {n}")

    combined = []
    if prepend is not None:
        prepend = asarray_safe(prepend, like=meta_from_array(a))
        if prepend.ndim == 0:
            shape = list(a.shape)
            shape[axis] = 1
            prepend = broadcast_to(prepend, tuple(shape))
        combined.append(prepend)

    combined.append(a)

    if append is not None:
        append = asarray_safe(append, like=meta_from_array(a))
        if append.ndim == 0:
            shape = list(a.shape)
            shape[axis] = 1
            append = np.broadcast_to(append, tuple(shape))
        combined.append(append)

    if len(combined) > 1:
        a = concatenate(combined, axis)

    sl_1 = a.ndim * [slice(None)]
    sl_2 = a.ndim * [slice(None)]

    sl_1[axis] = slice(1, None)
    sl_2[axis] = slice(None, -1)

    sl_1 = tuple(sl_1)
    sl_2 = tuple(sl_2)

    r = a
    for _ in range(n):
        r = r[sl_1] - r[sl_2]

    return r


@derived_from(np)