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• How to plot an animated graph

  2 août 2019, par Mukonza Sabastian Simbarashe

  Following along How to Create Animated Graphs in Python when constructing an animated plot then on writing the ffmpeg I get the following error :

  'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available

  After getting this error, I initially tried to install ffmpeg using pip by the following method :

  python -m install ffmpeg

  and it seems to have successfully installed ffmpeg, but going back to my code I still get the same error

  Find below my code :

  import numpy as np
  
  import pandas as pd
  
  import seaborn as sns
  
  import matplotlib
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  overdoses = pd.read_excel(r'C:\Users\ACER\Desktop\overdose_data_1999-2015.xls',sheet_name='Online',skiprows =6)
  
  
  
  def get_data(table,rownum,title):
  
      data = pd.DataFrame(table.loc[rownum][2:]).astype(float)
  
      data.columns = {title}
  
      return data
  
  
  
  title = 'Heroin Overdoses'
  
  d = get_data(overdoses,18,title)
  
  x = np.array(d.index)
  
  y = np.array(d['Heroin Overdoses'])
  
  overdose = pd.DataFrame(y,x)
  
  overdose.columns = {title}
  
  Writer = animation.writers['ffmpeg']

  Here is the stack trace :

  Traceback (most recent call last):
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 161, in __getitem__
  
      return self.avail[name]
  
  KeyError: 'ffmpeg'
  
  
  
  During handling of the above exception, another exception occurred:
  
  
  
  Traceback (most recent call last):
  
    File "", line 1, in <module>
  
      Writer = animation.writers['ffmpeg']
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 164, in __getitem__
  
      'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available
  
  </module>

• FFMPEG file writer in python 2.7

  6 avril 2017, par byBanachTarskiIamcorrect

  Trying to animate a string in python, i think my code is fine but just having difficulties with the file writer. My code is (based off https://jakevdp.github.io/blog/2012/08/18/matplotlib-animation-tutorial/) :

  import numpy as np
  
  import scipy as sci
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  plt.rcParams['animation.ffmpeg_path'] = 'C:\FFMPEG\bin\ffmpeg'
  
  
  
  
  
  s1=10.15
  
  gamma=(np.pi*np.sqrt(2))/2
  
  gamma=sci.special.jn_zeros(0,10)
  
  gamma1=gamma[9]
  
  gamma2=gamma[8]
  
  print gamma1,gamma2
  
  
  
  sigma=np.linspace(0,2*s1,10000)
  
  
  
  def xprime(sigma,t):
  
      alpha = gamma1*(np.cos(np.pi*t/s1)*np.cos((np.pi*sigma)/s1))
  
      beta = gamma1*(np.sin(np.pi*t/s1)*np.sin((np.pi*sigma)/s1))
  
      xprime=np.cos(alpha)*np.cos(beta)
  
      return xprime
  
  
  
  def yprime(sigma,t):
  
      alpha = gamma2*(np.cos(np.pi*t/s1)*np.cos((np.pi*sigma)/s1))
  
      beta = gamma2*(np.sin(np.pi*t/s1)*np.sin((np.pi*sigma)/s1))
  
      yprime=np.cos(alpha)*np.sin(beta)
  
      return yprime
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(-0.4, 0.4), ylim=(-3, 3))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      sigma=np.linspace(0,2*s1,10000)
  
      t = (i*2*s1)/200
  
      yint=sci.integrate.cumtrapz(yprime(sigma,t),sigma)
  
      xint=sci.integrate.cumtrapz(xprime(sigma,t),sigma)
  
      line.set_data(xint, yint)
  
      return line,
  
  
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init,
  
                             frames=200, interval=20, blit=True)
  
  
  
  FFwriter=animation.FFMpegWriter()
  
  anim.save('basic_animation.mp4', writer=FFwriter, fps=30, extra_args=['-vcodec', 'libx264'])
  
  
  
  plt.show()

  Currently getting the error message

  RuntimeError: Passing in values for arguments for arguments fps, codec, bitrate, extra_args, or metadata is not supported when writer is an existing MovieWriter instance. These should instead be passed as arguments when creating the MovieWriter instance.'

  I think my error is in the calling or placement of the FFMpeg file but i’m unsure what i’m doing wrong. Probably very obvious but can’t see it at the moment / unsure what the error message actually means.

• Saving video using matplotlib results in WinError 5 [duplicate]

  8 juillet 2015, par Chris

  This question already has an answer here :

  • Cannot save animation in matplotlib : Windows permission denied
    
    2 answers
    

  Using matplotlib it should be possible to animate videos and save them as mpeg. I have found a few tips and tricks on the web but I was not able to get it to work on my Windows 7 machine running Python 3.4. Here are two examples that I found on the web that both give me an exeption PermissionError: [WinError 5] Permission denied :

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  plt.rcParams['animation.ffmpeg_path'] = r'C:\Users\me\Desktop\ffmpeg-latest-win64-static\ffmpeg-20150702-git-03b2b40-win64-static\bin'
  
  
  
  metadata = dict(title='Movie Test', artist='Matplotlib',
  
          comment='Movie support!')
  
  writer = animation.FFMpegWriter(fps=15, metadata=metadata)
  
  
  
  fig = plt.figure()
  
  l, = plt.plot([], [], 'k-o')
  
  
  
  plt.xlim(-5, 5)
  
  plt.ylim(-5, 5)
  
  
  
  x0,y0 = 0, 0
  
  
  
  with writer.saving(fig, "writer_test.mp4", 100):
  
      for i in range(100):
  
          x0 += 0.1 * np.random.randn()
  
          y0 += 0.1 * np.random.randn()
  
          l.set_data(x0, y0)
  
          writer.grab_frame()

  And this one throws the same exeption :

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  plt.rcParams['animation.ffmpeg_path'] = r'C:\Users\wiesmeyrc\Desktop\ffmpeg-latest-win64-static\ffmpeg-20150702-git-03b2b40-win64-static\bin'
  
  
  
  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)
  
  
  
  FFwriter = animation.FFMpegWriter()
  
  anim.save('basic_animation.mp4', writer = FFwriter, fps=30, extra_args=['-vcodec', 'libx264'])

  [EDIT] : Here is the full stack trace :

  Traceback (most recent call last):
  
    File ".\matplotlib_animation.py", line 37, in <module>
  
      with writer.saving(fig, r'C:\Users\wiesmeyrc\Documents\Python Scripts\basic_animation.mp4', 100):
  
    File "C:\Anaconda3\lib\contextlib.py", line 59, in __enter__
  
      return next(self.gen)
  
    File "C:\Anaconda3\lib\site-packages\matplotlib\animation.py", line 186, in saving
  
      self.setup(*args)
  
    File "C:\Anaconda3\lib\site-packages\matplotlib\animation.py", line 176, in setup
  
      self._run()
  
    File "C:\Anaconda3\lib\site-packages\matplotlib\animation.py", line 204, in _run
  
      creationflags=subprocess_creation_flags)
  
    File "C:\Anaconda3\lib\subprocess.py", line 858, in __init__
  
      restore_signals, start_new_session)
  
    File "C:\Anaconda3\lib\subprocess.py", line 1111, in _execute_child
  
      startupinfo)
  
  PermissionError: [WinError 5] Zugriff verweigert
  
  </module>