[Numpy-discussion] Thoughts about zero dimensional arrays vs Python scalars
oliphant at ee.byu.edu
Sun Mar 20 22:28:42 EST 2005
Colin J. Williams wrote:
> It looks as though a decision has been made. I was among those who
> favoured abandoning rank-0 arrays, we lost.
I don't understand how you can say this. In what way have rank-0 arrays
not been abandoned for the new Array Scalar objects? By the way, these
array scalar objects can easily be explained as equivalent to the type
hierarchy of current numarray (it is essentially identical --- it's just
> To my mind rank-0 arrays add complexity for little benefit and make
> explanation more difficult.
I don't know what you mean. rank-0 arrays are built into the
arrayobject type. Removing them is actually difficult. The easiest
thing to do is to return rank-0 arrays whenever the operation allows
it. It is the confusion with desiring to use items in an array (which
are logically rank-0 arrays) as equivalent to Python scalars that
requires the Array Scalars that "bridge the gap" between rank-0 arrays
and "regular" Python scalars.
Perhaps you mean that "Array Scalars" add complexity for "little
beneift" and not "rank-0 arrays". To address that question: It may
add complexity, but it does add benefit (future optimization, array type
hierarchy, and a better bridge between the problem of current Python
scalars and array-conscious scalars). This rank-0 problem has been a
wart with Numeric for a long time. Most of us long-time users work
around it, but heavy users are definitely aware of the problem and a bit
annoyed. I think we have finally found a reasonable "compromise"
solution in the Array Scalars. Yes, it did take more work to implement
(and will take a little more work to maintain --- you need to add
methods to the GenericScalar class when you add them to the Array
Class), but I can actually see it working.
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