Re: [Matplotlib-users] Agg eps and bounding box / OO problems

[<bh...@de...>]

"John Hunter" <jd...@gm...> writes:

> On 2/5/07, Berthold H=C3=B6llmann <bhoel-lDxpuoTbsqf2eFz/2M...@pu...=
ane.org> wrote:
>
>> I get a file 'test.eps'. Using matplotlib 0.87.7 the PS bounding box
>> of the generated plot is far to wide. Is this a problem with my script
>> or a Problem of FigureCanvasAgg (and FigureCanvasPS)? What can I do to
>> get a tight bounding box?
>
> This is a problem with the way PS computes the bounding box -- it uses
> the bounding box of the Figure and ignores the fact that much of your
> figure is whitespace.  It should compute the bounding box of the
> visible figure elements, so this should be considered a bug.  To
> workaround, you can set the figure size to be more like the size of
> the content
>
>   fig =3D Figure((3,7))  # set the width and height in inches
>   canvas =3D FigureCanvas(fig)
>   ax =3D fig.add_subplot(111)
>   ax.plot([.5,.7],[1.5, 2.5])
>   ax.add_artist(Rectangle((.5, 1.5), .2, 1, fill=3DFalse))
>   ax.set_aspect("equal")
>   canvas.print_figure('test.eps')

So there is no way to calculate the size occupied by the visible
figure elements? In my target application I also have no easy way to
figure out the size of the resulting plot, I hoped matplotlib has a
way tp extract it from the plotted data.

something like

-----
ax.set_aspect("equal")
ax.autoscale_view()
w, h =3D fig.get_size_inches()
xmin, xmax =3D ax.get_xlim()
ymin, ymax =3D ax.get_ylim()
xext =3D xmax - xmin
yext =3D ymax - ymin
if xext < yext:
    w =3D h * xext/yext
else:
    h =3D w * yext/xext
-----

gives a tighter bounding box, still having somehow too much room in
the unchanged direction.

>> Further, when I leave out the "ax.plot" line, the generated figure is
>> missing the "Rectangle" and is showing only a pair of axes counting
>> from 0 to 1. Is that a bug of matplotlib or something I have to fix in
>> my script?
>
> Use add_patch instead of add_artist.  add_artist is the most generic
> method and Axes doesn't know how to query it's argument for it's data
> limits, which it then feeds to the autoscaler.  If you use add_line to
> add lines.Line2D and add_patch to add patches.Patch instances, then
> Axes will know how to introspect them and update the autoscaler.  But
> you will need to explicitly call "autoscale_view" before saving.
> Something like

I had tried "add_patch" but missed the ax.autoscale_view() call.

Thanks
Berthold
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ber...@xn... / <http://h=C3=B6llmanns.de/>
bh...@we...                 / <http://starship.python.net/crew/bhoel/>