matplotlib-devel

[matplotlib-devel] Transparent backgrounds for savefig

[S. v. d. W. <st...@su...>]

Hi all,

I'm generating plots for a document with a non-white background, and I
need the outer rectangle (the one is normally gray on the screen) to
be transparent.  Savefig doesn't seem to have such an option: is it
possible to do it already, and if not, would there be any interest in
a patch?

Regards
Stéfan

Re: [matplotlib-devel] Transparent backgrounds for savefig

[Michael D. <md...@st...>]

Something similar was added to SVN yesterday.  Pass "transparent=True" 
to savefig.  This will set both the figure rectangle and the axes 
rectangles to transparent.

If you just want a transparent figure rectangle, you can do:

  fig().figurePatch.set_alpha(0.0)

Maybe this should be made an option on the "transparent" kwarg to 
savefig, something like:

   transparent = 'figure' | 'figure_and_axes'

Or is that just making things too complicated?

Cheers,
Mike

Stéfan van der Walt wrote:
> Hi all,
>
> I'm generating plots for a document with a non-white background, and I
> need the outer rectangle (the one is normally gray on the screen) to
> be transparent.  Savefig doesn't seem to have such an option: is it
> possible to do it already, and if not, would there be any interest in
> a patch?
>
> Regards
> Stéfan
>
> -------------------------------------------------------------------------
> Check out the new SourceForge.net Marketplace.
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-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Re: [matplotlib-devel] Transparent backgrounds for savefig

[S. v. d. W. <st...@su...>]

2008/6/25 Michael Droettboom <md...@st...>:
> Maybe this should be made an option on the "transparent" kwarg to savefig,
> something like:
>
>  transparent = 'figure' | 'figure_and_axes'
>
> Or is that just making things too complicated?

Those options would both be very handy.

In the meantime, thanks for the workaround!  My hack was to export to
SVG, then edit with Inkscape (first compiled Inkscape for OSX :), save
to PNG and finally convert the PNG to a PNG that Firefox can
understand, using GIMP (also compiled for OSX).  Phew!

Regarding OSX: it seems that, for the first time in months, I can now
build matplotlib on OSX with gcc 4.1 without jumping through all sorts
of crazy loops.  Thanks!

Regards
Stéfan

Re: [matplotlib-devel] Transparent backgrounds for savefig

[John H. <jd...@gm...>]

On Wed, Jun 25, 2008 at 8:25 AM, Stéfan van der Walt <st...@su...> wrote:
> 2008/6/25 Michael Droettboom <md...@st...>:
>> Maybe this should be made an option on the "transparent" kwarg to savefig,
>> something like:
>>
>>  transparent = 'figure' | 'figure_and_axes'
>>
>> Or is that just making things too complicated?
>
> Those options would both be very handy.

Stefan -- just for a little background.  The figure has a
matplotlib.patches.Rectangle instance called "figurePatch" and the
axes has a Rectangle instance called axesPatch.  You can set any
property on them directly (facecolor, edgecolor, linewidth, linestyle,
alpha).  Eg,

  fig = plt.figure()
  fig.figurePatch.set_alpha(0.5)
  ax = fig.add_subplot(111)
  ax.axesPatch.set_alpha(0.5)

Michael's transparent kwarg is just a helper function to do this
automatically at save time w/o affecting the screen rendered figure.
For stylistic reasons, I'd like a new name for figurePatch and
rectanglePatch.  "background", "rectangle" and "patch" would all be
nicer.  I'm inclined toward "rectangle" -- I think I'll just put an
alias in Figure and Axes unless someone has a better idea.

JDH

Re: [matplotlib-devel] Transparent backgrounds for savefig

[Michael D. <md...@st...>]

"rectangle" might be a bad name for "axesPatch" since it can be a circle 
for polar plots, and ellipse for geo plots etc.

Cheers,
Mike

John Hunter wrote:
> On Wed, Jun 25, 2008 at 8:25 AM, Stéfan van der Walt <st...@su...> wrote:
>   
>> 2008/6/25 Michael Droettboom <md...@st...>:
>>     
>>> Maybe this should be made an option on the "transparent" kwarg to savefig,
>>> something like:
>>>
>>>  transparent = 'figure' | 'figure_and_axes'
>>>
>>> Or is that just making things too complicated?
>>>       
>> Those options would both be very handy.
>>     
>
> Stefan -- just for a little background.  The figure has a
> matplotlib.patches.Rectangle instance called "figurePatch" and the
> axes has a Rectangle instance called axesPatch.  You can set any
> property on them directly (facecolor, edgecolor, linewidth, linestyle,
> alpha).  Eg,
>
>   fig = plt.figure()
>   fig.figurePatch.set_alpha(0.5)
>   ax = fig.add_subplot(111)
>   ax.axesPatch.set_alpha(0.5)
>
> Michael's transparent kwarg is just a helper function to do this
> automatically at save time w/o affecting the screen rendered figure.
> For stylistic reasons, I'd like a new name for figurePatch and
> rectanglePatch.  "background", "rectangle" and "patch" would all be
> nicer.  I'm inclined toward "rectangle" -- I think I'll just put an
> alias in Figure and Axes unless someone has a better idea.
>
> JDH
>
> -------------------------------------------------------------------------
> Check out the new SourceForge.net Marketplace.
> It's the best place to buy or sell services for
> just about anything Open Source.
> http://sourceforge.net/services/buy/index.php
> _______________________________________________
> Matplotlib-devel mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
>   

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Re: [matplotlib-devel] Transparent backgrounds for savefig

[John H. <jd...@gm...>]

On Wed, Jun 25, 2008 at 9:09 AM, Michael Droettboom <md...@st...> wrote:
> "rectangle" might be a bad name for "axesPatch" since it can be a circle for
> polar plots, and ellipse for geo plots etc.

Ahh yes, mind still mushy even after a good night's sleep.  "patch" or
"background" I feel about the same.  "patch" isn't terribly mnemonic
unless you are a matlab user, but at least it points you to the base
class and is most consistent with the current name, in which the
"figure" part of "figurePatch" is simply redundant.

patch, going once, going twice,...

JDH

Re: [matplotlib-devel] Transparent backgrounds for savefig

[John H. <jd...@gm...>]

On Wed, Jun 25, 2008 at 9:23 AM, John Hunter <jd...@gm...> wrote:
> On Wed, Jun 25, 2008 at 9:09 AM, Michael Droettboom <md...@st...> wrote:
>> "rectangle" might be a bad name for "axesPatch" since it can be a circle for
>> polar plots, and ellipse for geo plots etc.
>
> Ahh yes, mind still mushy even after a good night's sleep.  "patch" or
> "background" I feel about the same.  "patch" isn't terribly mnemonic
> unless you are a matlab user, but at least it points you to the base
> class and is most consistent with the current name, in which the
> "figure" part of "figurePatch" is simply redundant.

I was just confused by the method "get_axes_patch" which looks like an
accessor method for the axesPatch, but instead is the method that
generates a new rectangle (or circle or whatever).  To add to the
confusion, there is the method get_frame, which returns the axesPatch
even though there is also an axesFrame (which was created by
get_axes_patch).  Is you head spinning like mine?

How about:

   _generate_axes_patch to replace get_axes_patch - internal class use only

   get_frame and get_patch deprecated - just use "patch" and "frame",
formerly "axesPatch" and "axesFrame".  We'll add a deprecation warning
to get_frame and keep axesPatch and axesFrame around as aliases.

Michael -- IIRC you added the axesFrame.  Was this to support to
separate drawing of the edge and face since our patches don't
(currently) have support for separate alpha channels for edge and
face.  Or are there additional motivations for the projection
backends?

JDH

Re: [matplotlib-devel] Transparent backgrounds for savefig

[Michael D. <md...@st...>]

John Hunter wrote:
> On Wed, Jun 25, 2008 at 9:23 AM, John Hunter <jd...@gm...> wrote:
>   
>> On Wed, Jun 25, 2008 at 9:09 AM, Michael Droettboom <md...@st...> wrote:
>>     
>>> "rectangle" might be a bad name for "axesPatch" since it can be a circle for
>>> polar plots, and ellipse for geo plots etc.
>>>       
>> Ahh yes, mind still mushy even after a good night's sleep.  "patch" or
>> "background" I feel about the same.  "patch" isn't terribly mnemonic
>> unless you are a matlab user, but at least it points you to the base
>> class and is most consistent with the current name, in which the
>> "figure" part of "figurePatch" is simply redundant.
>>     
>
> I was just confused by the method "get_axes_patch" which looks like an
> accessor method for the axesPatch, but instead is the method that
> generates a new rectangle (or circle or whatever).  To add to the
> confusion, there is the method get_frame, which returns the axesPatch
> even though there is also an axesFrame (which was created by
> get_axes_patch).  Is you head spinning like mine?
>   
Yes, I saw that when I added the transparent kwarg and was also 
confused, but thought best to leave it at the time... ;)
> How about:
>
>    _generate_axes_patch to replace get_axes_patch - internal class use only
>
>    get_frame and get_patch deprecated - just use "patch" and "frame",
> formerly "axesPatch" and "axesFrame".  We'll add a deprecation warning
> to get_frame and keep axesPatch and axesFrame around as aliases.
>
> Michael -- IIRC you added the axesFrame.  Was this to support to
> separate drawing of the edge and face since our patches don't
> (currently) have support for separate alpha channels for edge and
> face.  Or are there additional motivations for the projection
> backends?
It was so that the zorder could be something like:

   axesPatch
   ... data ...
   ... grids ...
   axesFrame

It prevents data from overlapping the axes frame.  This was most crucial 
in the PDF and Cairo backends where the clipping rectangle is 
pixel-aligned but the axes frame and background are not necessarily.  In 
the Agg backend, where we have more fine control, it actually doesn't 
really matter.

Cheers,
Mike

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Re: [matplotlib-devel] Transparent backgrounds for savefig

[Eric F. <ef...@ha...>]

Michael Droettboom wrote:

>>    get_frame and get_patch deprecated - just use "patch" and "frame",
>> formerly "axesPatch" and "axesFrame".  We'll add a deprecation warning
>> to get_frame and keep axesPatch and axesFrame around as aliases.
>>
>> Michael -- IIRC you added the axesFrame.  Was this to support to
>> separate drawing of the edge and face since our patches don't
>> (currently) have support for separate alpha channels for edge and
>> face.  Or are there additional motivations for the projection
>> backends?

I did it two years ago, r2415.

> It was so that the zorder could be something like:
> 
>    axesPatch
>    ... data ...
>    ... grids ...
>    axesFrame
> 

This was the main motivation, but the secondary thought was that it 
would facilitate doing something that people ask for now and then, which 
is allow one to specify only some axes boundaries instead of the whole 
rectangle.  A common plot style is to have axes lines on the left and 
bottom, for example; but sometimes people want only a line on the 
bottom, and I am sure that sooner or later someone will want top and 
right, or top and bottom, or whatever.  Obviously, I never got around to 
putting that option in place.

> It prevents data from overlapping the axes frame.  This was most crucial 
> in the PDF and Cairo backends where the clipping rectangle is 
> pixel-aligned but the axes frame and background are not necessarily.  In 
> the Agg backend, where we have more fine control, it actually doesn't 
> really matter.

No, I think it matters on all backends, especially if the frame is 
thick.  Whether the zorder above is what one wants may be a matter of 
taste, but on any backend it will make a difference in the way the plot 
looks.

Eric

> 
> Cheers,
> Mike
>