Module: animation

Inheritance diagram for mpltools.animation:

Animation class.

This implementation is a interface for Matplotlib’s FuncAnimation class, but with different interface for:

• Easy reuse of animation code.
• Logical separation of setup parameter (passed to __init__) and animation parameters (passed to animate).
• Unlike Matplotlib’s animation class, this Animation class clearly must be assigned to a variable (in order to call the animate method). The FuncAnimation object needs to be assigned to a variable so that it isn’t garbage-collected, but this requirement is confusing, and easily forgotten, because the user never uses the animation object directly.

Animation

class mpltools.animation.Animation

Bases: object

Base class to create animation objects.

To create an animation, simply subclass Animation and override the __init__ method to create a plot (self.fig needs to be assigned to the figure object here), and override update with a generator that updates the plot:

class RandomPoints(Animation):

    def __init__(self, width=10):
        self.fig, self.ax = plt.subplots()
        self.width = width
        self.ax.axis([0, width, 0, width])
        self.num_frames = 20

    def update(self):
        artists = []
        self.ax.lines = [] # Clean up plot when repeating animation.
        for i in np.arange(self.num_frames):
            x, y = np.random.uniform(0, self.width, size=2)
            artists.append(self.ax.plot(x, y, 'ro'))
            yield artists

pts = RandomPoints()
pts.animate()

Note: if you want to use blitting (see docstring for Animation.animate), You must yield a sequence of artists in update.

This Animation class does not subclass any of Matplotlib’s animation classes because the __init__ method takes arguments for creating the plot, while animate method is what accepts arguments that alter the animation.

Methods

animate(**kwargs)	Run animation.
init_background()	Initialize background artists.
save(filename, **kwargs)	Saves a movie file by drawing every frame.
update()	Update frame.

__init__()

Initialize plot for animation.

Replace this method to initialize the plot. The only requirement is that you must create a figure object assigned to self.fig.

animate(**kwargs)

Run animation.

Parameters :

interval : float, defaults to 200

Time delay, in milliseconds, between frames.

repeat : {True | False}

If True, repeat animation when the sequence of frames is completed.

repeat_delay : None

Delay in milliseconds before repeating the animation.

blit : {False | True}

If True, use blitting to optimize drawing. Unsupported by some backends.

init_background : function

If None, the results of drawing from the first item in the frames sequence will be used. This can also be added as a class method instead of passing to animate.

save_count : int

If saving a movie, save_count determines number of frames saved. If not defined, use num_frames attribute (if defined); otherwise, set to 100 frames.

init_background()

Initialize background artists.

Note: This method is passed to FuncAnimation as init_func.

save(filename, **kwargs)

Saves a movie file by drawing every frame.

Parameters :

filename : str

The output filename.

writer : matplotlib.animation.MovieWriter or str

Class for writing movie from animation. If string, must be ‘ffmpeg’ or ‘mencoder’, which identifies the MovieWriter class used. If None, use ‘animation.writer’ rcparam.

fps : float

The frames per second in the movie. If None, use the animation’s specified interval to set the frames per second.

dpi : int

Dots per inch for the movie frames.

codec : :

Video codec to be used. Not all codecs are supported by a given writer. If None, use ‘animation.codec’ rcparam.

bitrate : int

Kilobits per seconds in the movie compressed movie. A higher value gives a higher quality movie, but at the cost of increased file size. If None, use animation.bitrate rcparam.

extra_args : list

List of extra string arguments passed to the underlying movie utility. If None, use ‘animation.extra_args’ rcParam.

metadata : dict

Metadata to include in the output file. Some keys that may be of use include: title, artist, genre, subject, copyright, comment.

update()

Update frame.

Replace this method to with a generator that updates artists and calls an empty yield when updates are complete.