[Numpy-discussion] Indexing changes/deprecations

[Sebastian Berg]

Hey,

since I am working on the indexing. I was wondering about a few smaller
things:

  * 0-d boolean array, `np.array(0)[True]` (will work now) would
    give np.array([0]) as a copy, instead of the original array.
    I guess I could add a FutureWarning or so, but I am not sure
    and overall the chance of creating bugs seems low.

    (The boolean index should always add 1 dimension and here,
    remove 0 dimensions -> 1-d result.)

  * All index operations return a view; never the object. This
    means that `v = arr[...]` is slightly slower. But since it
    does not affect `arr[...] = vals`, I think the speed
    implications are negligible.

  * Does anyone have an idea if there is a way to change the subclass
    logic that view based item setting is implemented as:
        np.asarray(subclass[index]) = vals

    I somewhat think the subclass should rather implement `__setitem__`
    instead of relying on numpy calling its `__getitem__`, but I
    don't see how it can be changed.

  * Still thinking a bit about implementing a keepdims keyword or
    function, to handle matrix type logic mostly in the C-code.

And most importantly, is there any behaviour thing in the index
machinery that is bugging you, which I may have forgotten until now?

- Sebastian