如何用python制作电影

Question

I have some binary files with names ('Den_pro_resample" +'_sdf _'+ str(n)+'.dat') where n changes from 0 to 25.
I wrote a code to read these files and then plot the results with imshow command.
at the last step, I want to create a movie . to do that, first, I saved the imshow plots in the .png Format and then I used the avconv command to stitch the images together. unfortunately, my code creates an empty movie with no scene. now I have 2 questions:

1- would anyone please help me how can I finally create a movie with this code.

2- is there any method that without saving the figures, directly I create a movie??

here is the code:

import os
import sys #exit the code at a specific line
import subprocess 
import sdf
import numpy as np
import matplotlib.pyplot as plt 
#import time
#import matplotlib.animation as animation
#from IPython import display
from matplotlib.font_manager import FontProperties
fp = FontProperties('Symbola')

##################### information from EPOCH input.deck
nx,ny= 1200, 1600
xmin=-100e-6
xmax = 110e-6
ymin = -200e-6
ymax = 200e-6

X =np.linspace(xmin,xmax,nx) 
Y =np.linspace(ymin,ymax,ny)　

#################
for n in range(0,26):
  nstr = str(n)#.zfill(4)
  #print nstr
######################..... reading Density of Proton

  filename ="Den_pro_resample" +'_sdf_'+ str(n)+'.dat'
  with open(filename, 'rb') as f: #read binary file
      data = np.fromfile(f, dtype='float64', count=nx*ny) 
  Den_pro = np.reshape(data, [ny, nx], order='F')
  Den_pro = np.log10(Den_pro )

  ########################## Display proton density
  plt.subplot(312)

  fig2 = plt.imshow(Den_pro, extent=[X.min()*1e6, X.max()*1e6, Y.min()*1e6, Y.max()*1e6], vmin=24, vmax=30, cmap='brg',      aspect='auto')    
  plt.xlabel('x($\mu$m)')
  plt.ylabel('y($\mu$m)')
  plt.text(-80,-40,'Den_proton',color='red', fontsize=15)
  plt.colorbar()

  #plt.savefig( 'fig%04d.png' % n, bbox_inches='tight') #('test'+ str(n)+ '.png') 
  plt.pause(.1)
  plt.clf() 

  ############ create a movie

avconv -framerate 1 -i fig%04d.png -c:v libx264 -profile:v high -crf 20 -pix_fmt yuv420p movie.mp4".split()
#ffmpeg -r 10 -i fig%04d.png -pix_fmt yuv420p movie.mp4".split() 

Answer 1

You can use matplotlib 's animation :

#the other imports you need should also be included.
import matplotlib.animation as animation 

#create these
xdata, ydata = [], []
ln, = plt.plot([], [], 'ro', animated=True)


#and define this

def update(frame):
    #set xdata and ydata to be the new values you need (i.e. of the next frame)
    ln.set_data(xdata, ydata)
    return ln,


ani = FuncAnimation(fig2, update, 26)
writer = animation.writers['ffmpeg'](fps=30)

ani.save('demo.mp4',writer=writer,dpi=dpi)

and this would save your data to demo.mp4 .

You can look at the documentation here for more details.