[Numpy-discussion] 0-D arrays as scalars

Konrad Hinsen hinsen at cnrs-orleans.fr
Tue Jun 11 05:57:02 CDT 2002


Travis Oliphant <oliphant.travis at ieee.org> writes:

> Actually, the code in PyArg_ParseTuple asks the object it gets if it
> knows how to be a float.  0-d arrays for some time have known how to be
> Python floats.  So, I do not think this error occurs as you've
> described.  Could you demonstrate this error?

No, it seems gone indeed. I remember a lengthy battle due to this
problem, but that was a long time ago.

> The only exception to this that I've seen is the list indexing code
> (probably for optimization purposes).   There could be more places, but
> I have not found them or heard of them.  

Even for indexing, I don't see the point. If you test for the int type
and do conversion attempts only for non-ints, that shouldn't slow down
normal usage at all.

> have now.  I'm quite supportive of never returning Python scalars from
> Numeric array operations unless specifically requested (e.g. the
> toscalar method).  

I suppose this would be easy to implement, right? Then why not do it in
a test release and find out empirically how much code it breaks.

> presumption based?  If I encounter a Python object that I'm unfamiliar
> with, I don't presume to know how it will define multiplication. 

But if that object pretends to be a number type, a sequence type,
a mapping type, etc., I do make assumptions about its behaviour.

Konrad.
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