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• Python animation saves only one single frame

  5 octobre 2015, par JohnND

  I’m trying to save a python animation as a video file. The animation itself works fine with show(). But when I use save() I get a video file containing only one frame which stays on for the duration of the video. The duration itself seems correct (2 minutes).
  Here’s my script, it gets some data from files that are read by custom functions then use the data to make an animation. I’ve tried various alternatives like specifying ffmpeg as writer or using Agg as backend. So far it all gives the same result. Is there some obvious misuse of the animation module ?

  #!/usr/bin/env python
  
  
  
  import sys
  
  import os
  
  import matplotlib
  
  #matplotlib.use("Agg")
  
  import numpy as np
  
  import math as mh
  
  from pylab import *
  
  from matplotlib import animation as animation
  
  #plt.rcParams['animation.ffmpeg_path'] = '/usr/bin/ffmpeg'
  
  
  
  sys.path.append('/home/jseverin/bin/myPythonScripts/')
  
  import temp_profile_v4
  
  
  
  ##########################################################################
  
  #                          Function definition                           #
  
  ##########################################################################
  
  
  
  
  
  ##########################################################################
  
  #                                  Main                                  #
  
  ##########################################################################
  
  
  
  def main(args):
  
      log_file = args[1]
  
  
  
      lz, coords, instant_profiles, fig1, Nlayers = temp_profile_v4.main(["temp_profile_v4.py", "-i", log_file])
  
      close(fig1)
  
  
  
      # Layer thickness in angstroms
  
      thickA = lz/Nlayers
  
      thickA2 = thickA/2
  
  
  
  
  
      # We need to slice the array
  
      # We choose the width of the exclusion area as a fraction of the source/sink width
  
      fract = 1.0
  
      safeDist = fract*thickA
  
      #sliced_coords, sliced_temps = slice_prof(safeDist, thickA2, lz, slice_coords, slice_temps)
  
  
  
      Nframes = int(len(instant_profiles)/2)
  
  
  
      # Plot setup
  
  
  
      fig = figure(figsize=(12,8.5)) # initialise la figure
  
      line, = plot([],[], '-', linewidth=1.5, label = "T(z)")
  
  
  
      ymax = 0
  
      for prof in instant_profiles :
  
          dummy = max(prof)
  
          if dummy > ymax :
  
              ymax = dummy
  
  
  
      ymin = 999999999
  
      for prof in instant_profiles :
  
          dummy = min(prof)
  
          if dummy < ymin :
  
              ymin = dummy
  
  
  
      xlim([-0.1, lz])
  
      ylim([ymin, ymax])
  
      xlabel(r'z ($\AA$)', fontsize=14)
  
      ylabel('Temperature (K)', fontsize=14)
  
  
  
      # Show source and sink on graph
  
      axvspan(lz/4-thickA2, lz/4+thickA2, alpha=0.2, color='black', label=r"source/sink (a = %d $\AA$)" % int(round(thickA)))
  
      axvspan(3*lz/4-thickA2, 3*lz/4+thickA2, alpha=0.2, color='black')
  
      axvline(x=lz/4 + thickA2 + safeDist, linestyle='--', color='k')
  
      axvline(x=3*lz/4 - thickA2 - safeDist, linestyle='--', color='k')
  
  
  
      # fonction a definir quand blit=True
  
      # cree l'arriere de l'animation qui sera present sur chaque image
  
      def init():
  
          line.set_data([],[])
  
          return line,
  
  
  
      def animate(i): 
  
          step = 2*i
  
          line.set_data(coords, instant_profiles[step])
  
          return line,
  
  
  
      ani = animation.FuncAnimation(fig, animate, init_func=init, frames=Nframes, blit=True, interval=20, repeat=False)
  
  
  
      show()
  
  
  
      #FFwriter = animation.FFMpegWriter()
  
      #ani.save('dynamic_profile.mp4', writer = 'ffmpeg')
  
  
  
      # Set up formatting for the movie files
  
      #Writer = animation.writers['ffmpeg']
  
      #writer = Writer(fps=15, metadata=dict(artist='Me'), bitrate=1800)
  
      #ani.save('animation.mp4', writer=writer)
  
  
  
      ani.save('animation.mp4', fps=15)
  
  
  
  # End main
  
  
  
  if __name__=="__main__":
  
      main(sys.argv)

• Anomalie #2749 (Fermé) : Problème de cookie

  21 mars 2013, par guytarr °

  il y a bien http://forum.spip.net/fr_248457.html mais rien trouvé dans forum ou sur les listes de "récent".

• Anomalie #4272 : Vignettes considérée comme orphelins lors de la suppression des documents inutilisés

  11 février 2019, par Fabrice Véronneau

  Discussions sur le forum à ce sujet
  https://forum.spip.net/fr_271022.html
  https://forum.spip.net/fr_270796.html?debut_forums=%40270837#forum270837