[Numpy-discussion] New Operators in Python
Sat Mar 24 15:59:09 CDT 2007
On 3/24/07, Charles R Harris <email@example.com> wrote:
> On 3/24/07, Travis Oliphant <firstname.lastname@example.org> wrote:
> > Every so often the idea of new operators comes up because of the need to
> > do both "matrix-multiplication" and element-by-element multiplication.
> > I think this is one area where the current Python approach is not as
> > nice because we have a limited set of operators to work with.
> > One thing I wonder is if we are being vocal enough with the Python 3000
> > crowd to try and get additional operators into the language itself.
> > What if we could get a few new operators into the language to help us.
> > If we don't ask for it, it certainly won't happen.
> > My experience is that the difficulty of using the '*' operator for both
> > matrix multiplication and element-by-element multiplication depending on
> > the class of the object is not especially robust. It makes it harder to
> > write generic code, and we still haven't gotten everything completely
> > right.
> > It is somewhat workable as it stands, but I think it would be nicer if
> > we could have some "meta" operator that allowed an alternative
> > definition of major operators. Something like @* for example (just
> > picking a character that is already used for decorators).
> Yes indeed, this is an old complaint. Just having an infix operator would be
> an improvement:
> A dot B dot C
> Not that I am suggesting dot in this regard ;) In particular, it wouldn't
> parse without spaces. What about division? Matlab has both / and \ for left
> and right matrix division and something like that could call solve instead
> of inverse, leading to some efficiencies. We also have both dot and
> tensordot, which raises the problem of interpretation when ndim > 2.
I understand the convenience of more infix operators. And I sometimes
think one should just be able to define new ones at will ....
On the other hand, I'm now playing the devil's advocate:
A "math specific" language like Matlab has obviously an overwhelming
need for a second set of matrix/array operators. However, a language
-- as broadly used as -- Python might be just better off having a
simple, concise and limited set of infix operators. I assume that
this is the official argument.
I got especially "worried" when being remember of the "\"
right-to-left division operator. (As I said, it very useful to have
in Matlab, and I wish sometimes we could add things like this).
It is just important to keep the "con" - argument clearly in mind.
I hope this helps the discussion.
- Sebastian Haase
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