matplotlib-devel Mailing List for matplotlib

On Fri, Jul 9, 2010 at 5:22 PM, Ryan May <rm...@gm...> wrote:
> Hi,
>
> I've been "hard" at work over the last couple of months putting
> together a set of classes that simplifies the creation of animations
> in matplotlib. This started when I resurrected some old code for
> animations to give to a colleague, when I realized just how bad the
> old code was and how much better I could do. The result of this
> "afternoon" hack is what I'm ready to put forth.  Some of the goals:

In my haste to get this out, I forgot to mention that thanks go to Ben
Root for already banging on this quite a bit, giving quite a bit of
useful design feedback and helping me find some bugs.

Ryan

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

Hi,

I've been "hard" at work over the last couple of months putting
together a set of classes that simplifies the creation of animations
in matplotlib. This started when I resurrected some old code for
animations to give to a colleague, when I realized just how bad the
old code was and how much better I could do. The result of this
"afternoon" hack is what I'm ready to put forth.  Some of the goals:

* Run independently of the backend, unlike the examples we have now
(This is really accomplished by the Timer object we now have)
* Remove the boilerplate code of setting up loops
* Facilitate saving out animations as a movie file
* Provide a simple API that integrates well with the rest of Matplotlib
* Provide (optional) blitting support so that users don't have to
learn the ins and outs of blitting

Overall, I think I accomplished my goals, so I'm putting this out
there for wider comments. I've attached the python module which, when
run, displays two animated figures. There is also a git repository at:

http://github.com/dopplershift/Animation

which has some more examples, including ports of our old examples.
(The examples assume animation.py is in your python path somewhere,
which you'll have to do by hand. This can be as simple as dropping
animation.py into the directory).

Some things to note:
* The flow is broken into *a lot* of member functions. This is to
provide sufficient entry points for subclasses so that they really
only need to reimplement the parts they override. Optional blitting
support drove a lot of this.
* There are two main classes for end users:
  * FuncAnimation -- provide a callback which draws the next frame of animation
  * ArtistAnimation -- provide a sequence of collections of artists
which are turned off and on for each frame of animation
* There is support for saving movies with either mencoder or ffmpeg.
The config for this is really rough, and the place I could *really*
use suggestions. I'm not sure how best to go about it. I've been
unable to find a (currently maintained) python library for saving
movie files, so system calls to the utilities is the best I can do at
the moment. I'm not sure what to use on windows, since I'm not sure of
the state (and requirements) of mencode/ffmpeg on windows.

TODOs:
* Configuring saving movie files (formats, programs, etc.) (see above)
* Documentation (I promise not to commit until this is written)
* More examples (could use some more procedural examples, like
animating using data read from a socket, or inotify)

I welcome feedback on this, because I really want to see this become
an easy and bulletproof way of doing animations in matplotlib. This
seems to be an area of frequent question on the mailing list, and I
want this framework to lessen the questions, not increase them.

Ryan

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

Hi,

I just noticed that ContourSet only inherits ScalarMappable and
ContourLabeller, neither of which is an Artist subclass, which means
ContourSet is not an Artist. (And is why it does not have a remove()
method).  Anyone have any idea why and if we should correct that? I'm
not sure what the ramifications would be.

Ryan

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