[SciPy-user] scipy choice of defaults for matrix manipulation
Robert Kern
rkern at ucsd.edu
Thu Aug 5 20:26:39 CDT 2004
Alan G Isaac wrote:
[snip]
> Looking at briefly at Numeric and numarray, it seems they
> have made an effort to standardize on axis=0.
No, they don't. It's a fairly even mix of axis=0 and axis=-1.
> This is also
> true in the Matlab module. Wouldn't it be wise for SciPy
> to join the parade?
Not at this time. There's too much SciPy code that would need to be
rewritten, namely SciPy itself. The axis=-1 convention will be staying.
> (I.e., shouldn't these closely related
> and interdependent packages share a convention?
> Otherwise, this is going to be VERY confusing for users.
> (As it was for me.) Now when I call a such a function,
> I have to remember: is it a SciPy function, or a
> Numeric/numarray function?
Well, if it's SciPy, axis=-1 almost always (the deviations usually being
the functions which shadow Numeric functions). If it's Numeric, you also
have to remember if it's axis=0 or axis=-1. If it's numarray, then you
have other problems since SciPy is currently all-Numeric. The real
question you have to ask yourself when coding is "did SciPy overwrite
this Numeric function?", a question that needs to be asked for reasons
other than the choice of default axis.
I would also note that having a terminal running IPython is invaluable
when coding. The ? and ?? magic is usually better than a reference manual.
> Not a good situation, right?
It's arguable that SciPy functions which shadow Numeric functions should
have the same defaults. It is also arguable that SciPy functions should
be internally consistent, so when a Numeric function is overwritten (to
add genericity or whatever) it should follow the SciPy convention.
Neither choice has been rigorously implemented although after I poked
around in IPython for a minute or two, cumsum() appears to be the only
deviation from the first option. This might qualify as a bug.
> Thanks,
> Alan
--
Robert Kern
rkern at ucsd.edu
"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter
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