Slicing with None adds a new dimension. It's a common paradigm, though usually you'd use A[np.newaxis] or A[np.newaxis, ...] instead for readibility. (np.newaxis is None, but it's a lot more readable)

There's a good argument to be made that slicing with a single None shouldn't add a new axis, and only the more readable forms like A[None, :], A[..., None], etc should. However, that would rather seriously break backwards compatibility. There's a fair amount of existing code that assumes "A[None]" prepends a new axis.

On Thu, Dec 31, 2015 at 10:36 AM, Neal Becker <ndbecker2@gmail.com> wrote:

Neal Becker wrote:

> In my case, what it does is:

>

> A.shape = (5760,)

> A[none] -> (1, 5760)

>

> In my case, use of none here is just a mistake. But why would you want

> this to be accepted at all, and how should it be interpreted?

Actually, in my particular case, if it just acted as a noop, returning the

original array, that would have been perfect. No idea if that's a good

result in general.

_______________________________________________

NumPy-Discussion mailing list

NumPy-Discussion@scipy.org

https://mail.scipy.org/mailman/listinfo/numpy-discussion