Re[2]: [Matplotlib-users] xzeroaxis

[Alan G I. <ai...@am...>]

On Mon, 06 Sep 2004, John Hunter apparently wrote:
> I've not used set xzeroaxis.  I googled around a bit and gathered that
> this draws a horizontal line from xmin to xmax at y=0.

Right.

>  Fernando Perez and I talked a bit at scipy about
> adding some gnuplot compatibility functions and this would fit under
> that umbrella.  I'm interested in getting some feedback about whether
> folks think this is a good idea.

I care about functionality much more than syntax.
This is a common need, so it shd be easy to do.

>     from matplotlib.transforms import blend_xy_sep_transform
>     ax = gca()
>     trans = blend_xy_sep_transform( ax.transAxes, ax.transData)
>     plot([0,1], [0,0], transform=trans)
> Try this out and see if it behaves as you like.

So far so good.

> Rather than reusing the gnuplot names, it might be better to
> provide a method that always draws a line from xmin to xmax at a given
> height regardless of the xlim, and do the same for a vertical line at
> some x.

I agree.  I actually need the additional functionality.

So while we're generalizing let me dream.  Focus on the case
of vertical lines.  The ideal functionality would allow me
to use 'vlines' with a special value to indicate ymin and
ymax.  Ideally this same 'special values' convention would
extend to 'fill' (or maybe 'bar'), since I often need event
shading.  Perhaps the obvious special value is None?

fwiw,
Alan