[Numpy-discussion] why two versions of polyfit?

Charles R Harris charlesr.harris at gmail.com
Sun May 20 12:11:39 EDT 2012


On Sun, May 20, 2012 at 9:53 AM, Andreas Hilboll <lists at hilboll.de> wrote:

> > On Sun, May 20, 2012 at 9:37 AM, Charles R Harris
> > <charlesr.harris at gmail.com <mailto:charlesr.harris at gmail.com>> wrote:
> >
> >
> >
> >     On Sun, May 20, 2012 at 9:09 AM, Andreas Hilboll <lists at hilboll.de
> >     <mailto:lists at hilboll.de>> wrote:
> >
> >         Hi,
> >
> >         I just noticed that there's two polyfit functions, one in
> >         numpy.lib.polynomial, and one in numpy.polynomial. What's the
> >         reason for
> >         this? The calling signatures aren't identical (the
> numpy.polynomial
> >         version supports weights), and I couldn't find a notice on why
> two
> >         versions exist.
> >
> >
> >     There are two different polynomial objects, Polynomial and poly1d.
> >     The Polynomial object is part of a newer group that also contains
> >     Lengendre, Chebyshev, etc., and doesn't have some of the problems
> >     that poly1d has. Poly1d is an older implementation.
>
> I think it would be beneficial for the user if this fact was noted
> somewhere in the docstring of the Poly1d implementation. Especially
> since numpy.polyfit is pointing to that old implementation. When I saw
> the polyfit function in the numpy namespace, I didn't bother checking if
> there's anything more sophisticated.
>
> I could add the appropriate links in the "see also" sections of the
> Poly1d docstrings, if you guys agree.
>

That would be useful.


>
> > Oh, and the polyfit function in polynomial.polynomial isn't meant to be
> > used directly, it is mostly there to support the fit class function of
> > Polynomial. See the documentation here <
> http://preview.tinyurl.com/8289gfs>.
>
> Ah, okay. Thanks for that.
>
>
Chuck
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