matplotlib-users Mailing List for matplotlib

On Monday, January 9, 2012, Ethan Gutmann <eth...@gm...> wrote:
> Along these lines, it looks to me like plot_surface is not shading when I
would expect it to (maybe I just have the wrong expectations?)
>
> I would expect the following to create a surface with colors from the
colormap but shading from a lightsource.
>
>        surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1,
cmap=cm.jet,shade=True)
>
> However, axes3d.py requires facecolors to be set in order to generate
facecolors to shade...
>
> mpl_toolkits/mplot3d/axes3d.py
> line 1378-1380 mpl v1.1.0
>
>        # Shade the data
>        if shade and cmap is not None and fcolors is not None:
>            fcolors = self._shade_colors_lightsource(Z, cmap, lightsource)
>
> should the if statement be:
>        if shade and cmap is not None and fcolors is None:
>
> I'm not sure if this will screw anything else up, but it makes a lot more
sense to me as an API. Maybe there are other reasons to require facecolors
to be set?
>
> Ethan

No, you are right.  This is roughly the requested feature I was talking
about.  There are multiple features in plot_surface() that are entwined and
I would like to figure out how to separate them and allow users to pick and
choose.

Features I have identified:

Coloring edgelines (complicated to determine what color)
Coloring based on colormap
Coloring based on user-spec  facecolors
Shading the colors (may or may not include edge lines)
Interpolating facecolors (for edgelines, IIRC)

These are inter-dependent and need to be made orthogonal.

Note, all of this is from memory, details might differ.

Cheers!
Ben Root

Along these lines, it looks to me like plot_surface is not shading when I would expect it to (maybe I just have the wrong expectations?)  

I would expect the following to create a surface with colors from the colormap but shading from a lightsource.   

	surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet,shade=True)

However, axes3d.py requires facecolors to be set in order to generate facecolors to shade...

mpl_toolkits/mplot3d/axes3d.py
line 1378-1380 mpl v1.1.0

        # Shade the data
        if shade and cmap is not None and fcolors is not None:
            fcolors = self._shade_colors_lightsource(Z, cmap, lightsource)

should the if statement be: 
        if shade and cmap is not None and fcolors is None:

I'm not sure if this will screw anything else up, but it makes a lot more sense to me as an API. Maybe there are other reasons to require facecolors to be set? 

Ethan

On Jan 9, 2012, at 10:28 AM, Zoltán Vörös wrote:

> 
> 
> On 01/09/2012 05:46 PM, Benjamin Root wrote:
>> When we said that GTK is not supported, (1) is not an official 
>> decision, I think, (2) we mean the pure GTK *backend*.  We fully 
>> support the GTKAgg backend, which is superior to the GTK backend in 
>> every way.  Please try v1.1.0 before continuing.  There were many 
>> important changes to mplot3d between v1.0.1 and v1.1.0.
> Indeed, that was the case. The surface plot works as advertised now. 
> Thanks for helping out with this! Once I have a viable code for 
> phonging, I will send it to you in a personal mail.
> Cheers,
> Zoltán
> 
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On 01/09/2012 05:46 PM, Benjamin Root wrote:
> When we said that GTK is not supported, (1) is not an official 
> decision, I think, (2) we mean the pure GTK *backend*.  We fully 
> support the GTKAgg backend, which is superior to the GTK backend in 
> every way.  Please try v1.1.0 before continuing.  There were many 
> important changes to mplot3d between v1.0.1 and v1.1.0.
Indeed, that was the case. The surface plot works as advertised now. 
Thanks for helping out with this! Once I have a viable code for 
phonging, I will send it to you in a personal mail.
Cheers,
Zoltán

2012/1/9 Zoltán Vörös <zv...@gm...>

>
> On 01/09/2012 05:30 PM, Benjamin Root wrote:
>
> The problem is that the faces themselves are transparent. But if I set
> shade to False, it becomes solid, so that must be the solution.
>
>>
>>
> What version of mpl are you using?  For me (on master) I never get
> transparent faces.
>
> I have 1.0.1 that comes with ubuntu. I was considering installing 1.1, but
> then I saw that the gtk backend is not supported, so I decided against it.
>
>
When we said that GTK is not supported, (1) is not an official decision, I
think, (2) we mean the pure GTK *backend*.  We fully support the GTKAgg
backend, which is superior to the GTK backend in every way.  Please try
v1.1.0 before continuing.  There were many important changes to mplot3d
between v1.0.1 and v1.1.0.

Ben Root

On 01/09/2012 05:30 PM, Benjamin Root wrote:
> The problem is that the faces themselves are transparent. But if I set 
> shade to False, it becomes solid, so that must be the solution.
>
>
>
> What version of mpl are you using?  For me (on master) I never get 
> transparent faces.
I have 1.0.1 that comes with ubuntu. I was considering installing 1.1, 
but then I saw that the gtk backend is not supported, so I decided 
against it.

By the way, here is an example of the transparent faces (I think it 
won't show on the mailing list). I can definitely see through the 
surface. The code I used is

for y in range(ylen):
     for x in range(xlen):
         colors[x, y] = (1, 0.0, 1, 1.)

surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, facecolors=colors,
         linewidth=0.1, antialiased=False, shade=True)

2012/1/9 Zoltán Vörös <zv...@gm...>

>  Thanks for the reply!
>
>   surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, facecolors=colors,
>>         linewidth=0.0, antialiased=True)
>>
>
> Is the issue that you have transparent lines between the faces?  Set the
> "shade" kwarg to True and the "antialiased" kwarg to False.
>
> The problem is that the faces themselves are transparent. But if I set
> shade to False, it becomes solid, so that must be the solution.
>
> If the shading is not what you want, it has been a feature request to
> implement the smooth coloring that shading does, but without a
> lightsource.  I have yet to do this, and there have been some attempts to
> get this right, but nothing finalized yet.  Contributions would be welcomed!
>
> OK, I will try to get this done and send you an implementation.
> Cheers,
> Zoltán
>


What version of mpl are you using?  For me (on master) I never get
transparent faces.

Ben Root

Thanks for the reply!
>
>     surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1,
>     facecolors=colors,
>             linewidth=0.0, antialiased=True)
>
>
> Is the issue that you have transparent lines between the faces?  Set 
> the "shade" kwarg to True and the "antialiased" kwarg to False.
The problem is that the faces themselves are transparent. But if I set 
shade to False, it becomes solid, so that must be the solution.
> If the shading is not what you want, it has been a feature request to 
> implement the smooth coloring that shading does, but without a 
> lightsource.  I have yet to do this, and there have been some attempts 
> to get this right, but nothing finalized yet.  Contributions would be 
> welcomed!
OK, I will try to get this done and send you an implementation.
Cheers,
Zoltán

2012/1/8 Zoltán Vörös <zv...@gm...>

> colors = np.empty(X.shape, tuple)
> for y in range(ylen):
>     for x in range(xlen):
>         colors[x, y] = (0, 0, 1, 1)
>
> surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, facecolors=colors,
>         linewidth=0.0, antialiased=True)
>

Is the issue that you have transparent lines between the faces?  Set the
"shade" kwarg to True and the "antialiased" kwarg to False.

If the shading is not what you want, it has been a feature request to
implement the smooth coloring that shading does, but without a
lightsource.  I have yet to do this, and there have been some attempts to
get this right, but nothing finalized yet.  Contributions would be welcomed!

Ben Root

On Mon, Jan 9, 2012 at 5:28 AM,  <kei...@bt...> wrote:
> I just installed matplotlib 1.1.0.   When I try the animation examples from http://matplotlib.sourceforge.net/examples/animation/index.html, they just flash up a window for a fraction of a second, and then terminate with no message (animate_decay.py, strip_chart_demo.py, etc).    Is this what they are supposed to do?    The documentation at http://matplotlib.sourceforge.net/api/animation_api.html is very terse.    When I include the line
>
> im_ani.save('im.mp4')
>
> in animate_basic_example.py, I get this crash:
>
> kbriggs@gold:~> python animate_basic_example.py
>
> Traceback (most recent call last):
>  File "animate_basic_example.py", line 32, in <module>
>    im_ani.save('im.mp4')
>  File "/usr/local/lib/python2.7/site-packages/matplotlib/animation.py", line 127, in save
>    self._make_movie(filename, fps, codec, frame_prefix)
>  File "/usr/local/lib/python2.7/site-packages/matplotlib/animation.py", line 164, in _make_movie
>    stdout=PIPE, stderr=PIPE)
>  File "/usr/local/lib/python2.7/subprocess.py", line 679, in __init__
>    errread, errwrite)
>  File "/usr/local/lib/python2.7/subprocess.py", line 1228, in _execute_child
>    raise child_exception
> OSError: [Errno 2] No such file or directory

Saving generally requires ffmpeg. You could try installing that or
commenting out the call to save().

Given that saving is half-baked at this point, a good maintainer of
this code *cough*me*cough* would probably make a problem saving not
completely crap out the script.

Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma

I just installed matplotlib 1.1.0.   When I try the animation examples from http://matplotlib.sourceforge.net/examples/animation/index.html, they just flash up a window for a fraction of a second, and then terminate with no message (animate_decay.py, strip_chart_demo.py, etc).    Is this what they are supposed to do?    The documentation at http://matplotlib.sourceforge.net/api/animation_api.html is very terse.    When I include the line

im_ani.save('im.mp4')

in animate_basic_example.py, I get this crash:

kbriggs@gold:~> python animate_basic_example.py 

Traceback (most recent call last):
  File "animate_basic_example.py", line 32, in <module>
    im_ani.save('im.mp4')
  File "/usr/local/lib/python2.7/site-packages/matplotlib/animation.py", line 127, in save
    self._make_movie(filename, fps, codec, frame_prefix)
  File "/usr/local/lib/python2.7/site-packages/matplotlib/animation.py", line 164, in _make_movie
    stdout=PIPE, stderr=PIPE)
  File "/usr/local/lib/python2.7/subprocess.py", line 679, in __init__
    errread, errwrite)
  File "/usr/local/lib/python2.7/subprocess.py", line 1228, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

Keith

On 01/05/2012 05:58 PM, Benjamin Root wrote:
> 
> 
> On Thu, Jan 5, 2012 at 10:40 AM, Benjamin Root <ben...@ou...
> <mailto:ben...@ou...>> wrote:
> 
> 
>         At the very least, it would help in compartmentallizing all the possible
>         drawing attributes that are common across all artists.  Currently, I am
>         envisioning using a defaultdict object (which was introduced in python
>         2.5) or subclassing from it.  This might help in keeping compatibility
>         with existing code.  Subclassing would allow for modifying __get__ and
>         __set__ to treat some elements like 'c' and 'color', 'lw' and
>         'linewidth' and so on as the same.
> 
> 
> Grrrr, in defaultdict(), the default_factory is called without arguments, so a
> factory can't be made to produce a default value for a given key, unless I
> resort to more hackary...

FWIW, defaultdict() only uses the __missing__ dictionary hook, and that one is
passed the key.  It's easy to implement a similar class that calls the factory
with a key argument.

Georg