Re: [PyX-user] Simply Draw

[Armin S. <li...@ar...>]

Hallo Andr=E9,

> > I fear that I don't really understand what symmetry of x and y means
> > here.
>
> You may not have noticed (?!), that you can also do a
> data.function("x(y)=3D...", ...) ... it works equally well. There's just
> noting special regarding the x axis and/or x direction compared to the
> y direction.

Ok, I think, I'm a bit nearer to understanding the issue. Nice for plotting=
=20
inverse functions by the way. Once more I have to see that I'm very new to=
=20
PyX. There's so much... :-)

> I kindly object: your function and your paramfunction fix the order
> and the name of the axes involved. In that sense they're quite a
> restriction. They're a common usecase and thus they are certainly very
> helpful.
> [...]
> > Nonetheless if this contradicts the concept of symmetry, I think it cou=
ld
> > be added to the PyX core as functionxy() and paramfunctionxy() but still
> > be used as function() and paramfunction() by simplydraw alternatively.
>
> That's fine, but you may spend some time whether you really want to
> introduce such a different meaning. If you really want to do so I'll
> not complain. You're free to do so, but I ask you to at least spend a
> few seconds before doing you final decision ... ;-)

I'm thinking about it... If I now understand the problem correctly, the=20
current implementation is bad mainly because
=2D it fixes the order
=2D and the name of the axes involved.

I have solved (at least I hope so) the issue of fixed order using the=20
following code snippet
        if expression.func_code.co_varnames =3D=3D ('y',):
            string =3D "x(y)=3Dexpression(y)"
        else:
            string =3D "y(x)=3Dexpression(x)"
which should yield some more symmetry in the sense that it does matter whet=
her=20
a function is defined as
  f =3D lambda x: sin(x)
versus
  f =3D lambda y: sin(y).

This issue does not really appear for paramfunction since all you have to d=
o=20
for swapped axes is to return the values (x,y) swapped. So there is at leas=
t=20
from a functional point of view little to gain (although I might be wrong=20
here...).

Just a note to the named axes. If this would be wanted one could take the=20
function name into account (not useful for lambda style functions though) t=
o=20
allow for some settings, but I can't think of a really useful and obvious w=
ay=20
(and that's what it should be in my opinion).

Thanks for pointing me to this issue!

Cheers
=2D-=20
Armin Straub