When you have a complicated 3D plot to show in a video or slideshow, it can be nice to animate it:

I obtained this surface with

import matplotlib.pyplot as plt from matplotlib import cm from mpl_toolkits.mplot3d import axes3d fig = plt.figure() ax = fig.add_subplot(111, projection='3d') X, Y, Z = axes3d.get_test_data(0.05) s = ax.plot_surface(X, Y, Z, cmap=cm.jet) plt.axis('off') # remove axes for visual appeal

To animate it I created the function rotanimate that you can use like that:

import numpy as np angles = np.linspace(0,360,21)[:-1] # A list of 20 angles between 0 and 360 # create an animated gif (20ms between frames) rotanimate(ax, angles,'movie.gif',delay=20) # create a movie with 10 frames per seconds and 'quality' 2000 rotanimate(ax, angles,'movie.mp4',fps=10,bitrate=2000) # create an ogv movie rotanimate(ax, angles, 'movie.ogv',fps=10)

Here is the source-code:

import matplotlib.pyplot as plt from matplotlib import cm from mpl_toolkits.mplot3d import axes3d import os, sys import numpy as np ##### TO CREATE A SERIES OF PICTURES def make_views(ax,angles,elevation=None, width=4, height = 3, prefix='tmprot_',**kwargs): """ Makes jpeg pictures of the given 3d ax, with different angles. Args: ax (3D axis): te ax angles (list): the list of angles (in degree) under which to take the picture. width,height (float): size, in inches, of the output images. prefix (str): prefix for the files created. Returns: the list of files created (for later removal) """ files = [] ax.figure.set_size_inches(width,height) for i,angle in enumerate(angles): ax.view_init(elev = elevation, azim=angle) fname = '%s%03d.jpeg'%(prefix,i) ax.figure.savefig(fname) files.append(fname) return files ##### TO TRANSFORM THE SERIES OF PICTURE INTO AN ANIMATION def make_movie(files,output, fps=10,bitrate=1800,**kwargs): """ Uses mencoder, produces a .mp4/.ogv/... movie from a list of picture files. """ output_name, output_ext = os.path.splitext(output) command = { '.mp4' : 'mencoder "mf://%s" -mf fps=%d -o %s.mp4 -ovc lavc\ -lavcopts vcodec=msmpeg4v2:vbitrate=%d' %(",".join(files),fps,output_name,bitrate)} command['.ogv'] = command['.mp4'] + '; ffmpeg -i %s.mp4 -r %d %s'%(output_name,fps,output) print command[output_ext] output_ext = os.path.splitext(output)[1] os.system(command[output_ext]) def make_gif(files,output,delay=100, repeat=True,**kwargs): """ Uses imageMagick to produce an animated .gif from a list of picture files. """ loop = -1 if repeat else 0 os.system('convert -delay %d -loop %d %s %s' %(delay,loop," ".join(files),output)) def make_strip(files,output,**kwargs): """ Uses imageMagick to produce a .jpeg strip from a list of picture files. """ os.system('montage -tile 1x -geometry +0+0 %s %s'%(" ".join(files),output)) ##### MAIN FUNCTION def rotanimate(ax, angles, output, **kwargs): """ Produces an animation (.mp4,.ogv,.gif,.jpeg,.png) from a 3D plot on a 3D ax Args: ax (3D axis): the ax containing the plot of interest angles (list): the list of angles (in degree) under which to show the plot. output : name of the output file. The extension determines the kind of animation used. **kwargs: - width : in inches - heigth: in inches - framerate : frames per second - delay : delay between frames in milliseconds - repeat : True or False (.gif only) """ output_ext = os.path.splitext(output)[1] files = make_views(ax,angles, **kwargs) D = { '.mp4' : make_movie, '.ogv' : make_movie, '.gif': make_gif , '.jpeg': make_strip, '.png':make_strip} D[output_ext](files,output,**kwargs) for f in files: os.remove(f) ##### EXAMPLE if __name__ == '__main__': fig = plt.figure() ax = fig.add_subplot(111, projection='3d') X, Y, Z = axes3d.get_test_data(0.05) s = ax.plot_surface(X, Y, Z, cmap=cm.jet) plt.axis('off') # remove axes for visual appeal angles = np.linspace(0,360,21)[:-1] # Take 20 angles between 0 and 360 # create an animated gif (20ms between frames) rotanimate(ax, angles,'movie.gif',delay=20) # create a movie with 10 frames per seconds and 'quality' 2000 rotanimate(ax, angles,'movie.mp4',fps=10,bitrate=2000) # create an ogv movie rotanimate(ax, angles, 'movie.ogv',fps=10)

Advertisements