Travis Oliphant <oliphant@ee.byu.edu> writes:
I've updated the PEP to conform to what I think is the best hybrid solution propsed and that is to implement a tree of PythonTypes in C whose leaves are (to the Python user) new rank-0 arrays.
For the purpose of differentiating between basic and advanced indexing, are rank 0 arrays considered scalars or arrays? Does their presence among indices trigger advanced indexing? For sequence behaviour len, indexing and iteration should work consistently, i.e., "a[i] for i in xrange(len(a))" and "x for x in a" should identically generate the contents of a. Currently indexing and iteration occur along the first dimension, which for rank 0 arrays does not exist. I understand that there is no burning desire to completely switch to Matlab-style one-dimensional indexing. The alternatives are then giving rank 0 arrays exceptional semantics inconsistent with other arrays or raising an exception if len or iteration is applied to a rank 0 array. Without exceptional semantics the only index expression that makes sense is a[()]. I would favor consistency here and raise an exception but there is one matter that raises some doubt: do programs expect that if __len__ and __iter__ exist they will not fail? Converting scalars back to arrays: they should be rank 0. Rank 1 would be Matlabish nonsense, except that Matlab is even more nonsensical and uses rank 2. But when is such conversion needed? If it is only for operations with other arrays then broadcasting is likely to occur immediately. -- Timo Korvola <URL:http://www.iki.fi/tkorvola>