On Fri, 2013-04-19 at 23:02 +0530, Robert Kern wrote: > On Fri, Apr 19, 2013 at 9:40 PM, Sebastian Berg > <sebast...@sipsolutions.net> wrote: > > > Fun fact, array[()] will convert a 0-d array to a scalar, but do nothing > > (or currently create a view) for other arrays. Which is actually a good > > question. Should array[()] force a view or not? > > Another fun fact: scalar[()] gives you a rank-0 array. :-) >
Hahahaha, thats pretty (I would say bug). > I think the array[()] behavior follows logically as a limiting form of > multidimensional indexing. Given rank-3 array, > > array[(i, j, k)] gives a scalar > array[(i, j)] gives a rank-1 view of the last axis > array[(i,)] gives a rank-2 view of the last 2 axes > array[()] gives a rank-3 view of the last 3 axes (i.e. all of them) > > The rank-N-general rules look like so: For a rank-N array, an N-tuple > gives a scalar. Subsequent (N-M)-tuples gives appropriate rank-M views > picked out by the tuple. > > I can't explain the scalar[()] behavior, though. :-) > Another special case... It doesn't hit the normal indexing code, and so it can never hit the tuple of integers special case to get converted back to a scalar. But it also always gets converted to an array first. So many special cases that are hard to miss, there is a reason I started rewriting it ;). Still not sure if one should force views sometimes though, but I doubt it matters... - Sebastian > -- > Robert Kern > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
