matplotlib-devel Mailing List for matplotlib

All,
 
I have a question regarding the default alpha value for an Artist. Why is it 1.0 instead of None? The color conversion code takes
into account if alpha is None and having it default to something other than None makes it impossible for any Patch to have a
fill_color specified as an RGBA value (and possibly other Artist sub-classes). Should this be something else, or should the
Patch.set_facecolor method pre-process the incoming color value and set any specified alpha as appropriate (I hope not since this
would cause the color value to be processed several times)?
 
Thanks,
--James Evans

I'm seeing problems with reversed colormaps (attached code and image).
The problem seems to be with colormaps that are specified functionally
or that don't have equal numbers of red, green, and blue entries. For
instance, 'flag', 'rainbow', and 'gist_earth'.
Furthermore, 'gist_rainbow_r' and 'terrain_r' don't plot at all with
the attached code.
I presume this is a regression from earlier behavior, since quite a
few colormaps are affected. svn shows some cleanup to the colormap
code this summer. Can someone with more familiarity with that code
point to the problem?
Thanks,
Eric

I don't have a patch. I just wrote a key handler that runs the snippet
I gave when "q" is pressed. I hope there's a better way to do it anyway :)
Georg
Jae-Joon Lee schrieb:
> Can you post your patch so that others can review?
> 
> Regards,
> 
> -JJ
> 
> 
> On Wed, Oct 21, 2009 at 3:23 AM, Georg Brandl <g.b...@gm...> wrote:
>> Hi,
>>
>> one thing I missed when I switched from Gnuplot to matplotlib was that I
>> can't press "q" to close a window but have to use the window manager; in
>> one environment I work in that means I have to use the mouse to close a
>> window.
>>
>> I made a custom key handler that does the following:
>>
>> try:
>> event.canvas.manager.destroy()
>> except AttributeError:
>> pass
-- 
Thus spake the Lord: Thou shalt indent with four spaces. No more, no less.
Four shall be the number of spaces thou shalt indent, and the number of thy
indenting shall be four. Eight shalt thou not indent, nor either indent thou
two, excepting that thou then proceed to four. Tabs are right out.

Can you post your patch so that others can review?
Regards,
-JJ
On Wed, Oct 21, 2009 at 3:23 AM, Georg Brandl <g.b...@gm...> wrote:
> Hi,
>
> one thing I missed when I switched from Gnuplot to matplotlib was that I
> can't press "q" to close a window but have to use the window manager; in
> one environment I work in that means I have to use the mouse to close a
> window.
>
> I made a custom key handler that does the following:
>
>    try:
>      event.canvas.manager.destroy()
>    except AttributeError:
>      pass
>
> which seems to work, at least with GtkAgg (I didn't venture to find out
> why the AttributeError is raised, it works in spite of that).
>
> Would it make sense to have that shortcut by default (and working for all
> windowing backends)?
>
> Georg
>
> --
> Thus spake the Lord: Thou shalt indent with four spaces. No more, no less.
> Four shall be the number of spaces thou shalt indent, and the number of thy
> indenting shall be four. Eight shalt thou not indent, nor either indent thou
> two, excepting that thou then proceed to four. Tabs are right out.
>
>
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The bug was actually in the path simplification. In really degenerate 
cases (bravo for finding it) of paths that are completely outside of the 
clip region, it would create a path with a single LINETO command.
This is now fixed in SVN on the branch and trunk.
Mike
Michael Droettboom wrote:
> Jouni K. Seppänen wrote:
> 
>> Jeff Whitaker <js...@fa...> writes:
>>
>> 
>> 
>>> Jouni: That test script now crashes with:
>>>
>>> File "/Users/jwhitaker/lib/python/matplotlib/backends/backend_pdf.py", 
>>> line 1214, in pathOperations
>>> raise ValueError, 'Path lacks initial MOVETO'
>>> ValueError: Path lacks initial MOVETO
>>> 
>>> 
>> I think this confirms my suspicion that the bug is really elsewhere. A
>> path in PDF needs to begin with a "m" that sets the initial point, and
>> that particular Path object only consisted of one LINETO operation. Am I
>> correct in thinking that this is an invalid path?
>> 
>> 
> Yes -- that path should be considered invalid, though the Path class 
> doesn't do any verification. I'll add this. I'm surprised that it's 
> coming from the line class, which in general doesn't allow for 
> customization of the path codes. There must be something unanticipated 
> happening.
>
> Cheers,
> Mike
>
> 
-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Jouni K. Seppänen wrote:
> Jeff Whitaker <js...@fa...> writes:
>
> 
>> Jouni: That test script now crashes with:
>>
>> File "/Users/jwhitaker/lib/python/matplotlib/backends/backend_pdf.py", 
>> line 1214, in pathOperations
>> raise ValueError, 'Path lacks initial MOVETO'
>> ValueError: Path lacks initial MOVETO
>> 
>
> I think this confirms my suspicion that the bug is really elsewhere. A
> path in PDF needs to begin with a "m" that sets the initial point, and
> that particular Path object only consisted of one LINETO operation. Am I
> correct in thinking that this is an invalid path?
> 
Yes -- that path should be considered invalid, though the Path class 
doesn't do any verification. I'll add this. I'm surprised that it's 
coming from the line class, which in general doesn't allow for 
customization of the path codes. There must be something unanticipated 
happening.
Cheers,
Mike
-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Jeff Whitaker <js...@fa...> writes:
> Jouni: That test script now crashes with:
>
> File "/Users/jwhitaker/lib/python/matplotlib/backends/backend_pdf.py", 
> line 1214, in pathOperations
> raise ValueError, 'Path lacks initial MOVETO'
> ValueError: Path lacks initial MOVETO
I think this confirms my suspicion that the bug is really elsewhere. A
path in PDF needs to begin with a "m" that sets the initial point, and
that particular Path object only consisted of one LINETO operation. Am I
correct in thinking that this is an invalid path?
I'm not too familiar with Path (and I'm terribly busy today) but I think
the way to catch this bug is to add a sanity check to Path, similar to
the check in the pdf backend that produces that error. Then the
traceback would show what code is creating the invalid path -- the
traceback from the backend is too late in the execution to tell us that.
-- 
Jouni K. Seppänen
http://www.iki.fi/jks