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• Can't save matplotlib animation

  2 janvier 2020, par renger

  I am trying to get a simple animation saved using ffmpeg. I followed a tutorial to install ffmpeg, and I can now access it from the command prompt.

  Now I run this piece of code :

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = np.linspace(0, 2, 1000)
  
      y = np.sin(2 * np.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init,
  
                                 frames=200, interval=20, blit=True)
  
  
  
  mywriter = animation.FFMpegWriter()
  
  anim.save('mymovie.mp4',writer=mywriter)
  
  
  
  plt.show()

  I get this error :

  Traceback (most recent call last):
  
    File "<stdin>", line 1, in <module>
  
     File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 523, in runfile
  
      execfile(filename, namespace)
  
    File "C:\Users\Renger\.xy\startups\b.py", line 23, in <module>
  
      anim.save('mymovie.mp4',writer=mywriter)
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 609, in save
  
      with writer.saving(self._fig, filename, dpi):
  
    File "C:\Python27\lib\contextlib.py", line 17, in __enter__
  
      return self.gen.next()
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 166, in saving
  
      self.setup(*args)
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 156, in setup
  
      self._run()
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 183, in _run
  
      stdin=subprocess.PIPE)
  
    File "C:\Python27\lib\subprocess.py", line 711, in __init__
  
      errread, errwrite)
  
    File "C:\Python27\lib\subprocess.py", line 948, in _execute_child
  
      startupinfo)
  
  WindowsError: [Error 2] Het systeem kan het opgegeven bestand niet vinden
  
  </module></module></stdin>

  The last dutch sentence does mean something like : The system can’t find the specified file.

  What do these errors mean, and how can I solve them ?

• Anaconda ffmpeg package as a MovieWriter for Matlibplot-Animation

  28 décembre 2019, par DScott

  There was a useful discussion on this question in the following link, but i don’t have 50 reputation so cant comment there, and i wish clarification on a suggestion within the post.

  I wish to create MP4 videos using python. I work in an environment where I am prohibited from installing ffmpeg from http://ffmpeg.zeranoe.com/builds/

  A user named Fiat suggested installing a package named ffmpeg :

  https://github.com/kkroening/ffmpeg-python

  I have installed the package through Anaconda. This solved the issue for the original questioner, however I have had no such success.

  Could anyone advise how to use the ffmpeg package to allow the Matplotlib-Animation package to create MP4 videos ?

• Python matplotlib.animation [Errno 13] Permission denied

  5 décembre 2019, par Fishman

  I am trying to create a simple animated histogram and save it as a .mp4 using matplotlib and ffmpeg on a mac. I have already installed ffMpeg, specified the ffmpeg path, and now I am getting a permission denied error when writing to a folder in my desktop. I tried running as sudo and still get the same error. Help is much appreciated, thank you !

  Here is the code :

  df = pd.read_csv('.../data.csv')
  
  
  
  df = df.dropna()
  
  #Get list of weeks
  
  weeks = df.ot_date.unique()
  
  fig, ax = plt.subplots()
  
  
  
  data = df.intervals_filled[df['ot_date'].isin([weeks[0]])]
  
  n, bins = np.histogram( data , 20)
  
  
  
  # get the corners of the rectangles for the histogram
  
  left = np.array(bins[:-1])
  
  right = np.array(bins[1:])
  
  bottom = np.zeros(len(left))
  
  top = bottom + n
  
  nrects = len(left)
  
  
  
  # here comes the tricky part -- we have to set up the vertex and path
  
  # codes arrays using moveto, lineto and closepoly
  
  
  
  # for each rect: 1 for the MOVETO, 3 for the LINETO, 1 for the
  
  # CLOSEPOLY; the vert for the closepoly is ignored but we still need
  
  # it to keep the codes aligned with the vertices
  
  nverts = nrects*(1 + 3 + 1)
  
  verts = np.zeros((nverts, 2))
  
  codes = np.ones(nverts, int) * path.Path.LINETO
  
  codes[0::5] = path.Path.MOVETO
  
  codes[4::5] = path.Path.CLOSEPOLY
  
  verts[0::5, 0] = left
  
  verts[0::5, 1] = bottom
  
  verts[1::5, 0] = left
  
  verts[1::5, 1] = top
  
  verts[2::5, 0] = right
  
  verts[2::5, 1] = top
  
  verts[3::5, 0] = right
  
  verts[3::5, 1] = bottom
  
  
  
  barpath = path.Path(verts, codes)
  
  patch = patches.PathPatch(
  
      barpath, facecolor='green', edgecolor='yellow', alpha=0.5)
  
  ax.add_patch(patch)
  
  
  
  ax.set_xlim(left[0], right[-1])
  
  ax.set_ylim(bottom.min(), top.max()+40)
  
  ax.set_xlabel('Number of intervals/week')
  
  ax.set_ylabel('Count of CSAs')
  
  plt.rcParams['animation.ffmpeg_path'] = '/usr/local/Cellar/ffmpeg'
  
  FFwriter = animation.FFMpegWriter()
  
  
  
  def animate(i):
  
      print i
  
      # simulate new data coming in
  
      data = df.intervals_filled[df['ot_date'].isin([weeks[i-1]])]
  
      n, bins = np.histogram(data, 20)
  
      yearweek = str(weeks[i-1])
  
      year = yearweek[0:4]
  
      week = yearweek[4:]
  
      title = 'Week %(wk)s of %(yr)s' %{'wk': week, 'yr': year}
  
      ax.set_title(title)
  
      top = bottom + n
  
      verts[1::5, 1] = top
  
      verts[2::5, 1] = top
  
      return [patch, ]
  
  
  
  ani = animation.FuncAnimation(fig, animate, 53,interval=1000, repeat=False)
  
  ani.save('/Users/.../Desktop/1b.mp4', writer = FFwriter)
  
  plt.show()

  And here is the traceback :

  Traceback (most recent call last):
  
    File "/Users/Fishman1049/Desktop/reserves_histogram_timeline/python/1b_text.py", line 109, in <module>
  
      ani.save('/Users/Fishman1049/Desktop/1b', writer = FFwriter)
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/site-packages/matplotlib/animation.py", line 761, in save
  
      with writer.saving(self._fig, filename, dpi):
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/contextlib.py", line 17, in __enter__
  
      return self.gen.next()
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/site-packages/matplotlib/animation.py", line 186, in saving
  
      self.setup(*args)
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/site-packages/matplotlib/animation.py", line 176, in setup
  
      self._run()
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/site-packages/matplotlib/animation.py", line 204, in _run
  
      creationflags=subprocess_creation_flags)
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/subprocess.py", line 710, in __init__
  
      errread, errwrite)
  
    File "/Users/Fishman1049/anaconda/lib/python2.7/subprocess.py", line 1335, in _execute_child
  
      raise child_exception
  
  OSError: [Errno 13] Permission denied
  
  </module>

  I am running matplotlib version 1.5.1, just installed FFmpeg today using homebrew, spyder 2.3.8, python 2.7 and OS X 10.10.5. Thank you !.