[PYTHON] Make a gif animation from a serial number file with matplotlib

** What you can do by reading this article ** Matplotlib can create gif animations from serial number data files

I can now make videos with gnuplot (Create videos from serial number data with gnuplot), but I want to be able to make videos with matplotlib anyway. !!

--Environment - macOS mojave 10.14.6 - Python 3.7.5

First, let's animate the sine curve as a practice. The basic method of making a gif animation is described in detail in the next article.

Here is a reference for the basic settings. Easy animation with matplotlib (mp4, gif)

The drawing method is briefly written here and is easy to understand. Make animation with matplotlib

gif_anime.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation

fig = plt.figure()
ax = fig.add_subplot(111)
#List to put Line2D object
ims = []

for i in range(10):
    x = np.array(range(60))
    Y  = np.sin(x/5 - i * 5)
    im = ax.plot(Y, color='blue')
    ims.append(im) #Add each frame image to ims

#Animation generation
ani = animation.ArtistAnimation(fig, ims, interval=100, blit=True, repeat_delay=1000)

#Save
ani.save("sample.gif", writer="pillow")

#display
plt.show()

You can make a gif animation like this (if it doesn't work, click it and try it in another window. When I uploaded it to Qiita, it stopped looping infinitely, but if I do it at hand, it will loop infinitely).

Options such as ʻinterbal`` repeat_delay` are described in detail in the next article. Make graph (Matplotlib) animation with Python (ArtistAnimation)

Next, let's try ** "animate the serial number file of the calculation result" ** as used in the research presentation. It would be easy if I could draw the anime I mentioned earlier. All you have to do is change the for part of the above code to read the calculation result.

anime_gif2.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import matplotlib.cm as cm

fig = plt.figure()
ax = fig.add_subplot(111)
#List to put Line2D object
ims = []

#Axis settings, etc.
ax.set_xscale('log')
ax.set_yscale('log')
ax.set_xlim(0.1, 10.0)
ax.set_ylim(1, 5000)

#Number of calculation result files
filenum = 10
for i in range(filenum):
    r, sd = np.loadtxt("./data%01d.dat" % (i), comments='#', unpack=True) #Read repeatedly from data00 to data09
    im = ax.plot(r, sd, "-", color='blue', linewidth=1)
    ims.append(im) #Add each frame image to ims

#Animation generation
ani = animation.ArtistAnimation(fig, ims, interval=500, blit=True, repeat_delay=100)

#Save
ani.save("anime.gif", writer="pillow")

#display
plt.show()

However, in this case, the list called im will be prepared before drawing. As the number of files to be read increases, and when trying to make more 3D animation, drawing becomes difficult. Therefore, I would like to draw each frame of the animation.

anime_gif3.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation

fig = plt.figure()
ax = fig.add_subplot(111)

artists = []
im, = ax.plot([], [])

#Axis settings, etc.
ax.set_xscale('log')
ax.set_yscale('log')
ax.set_xlim(0.1, 10.0)
ax.set_ylim(1, 5000)

#Number of calculation result files
filenum = 10

#Call this function repeatedly to draw
#I increases by 1 each time you call
def update_anim(i):
    r, sd = np.loadtxt("./data%01d.dat" % (i), comments='#', unpack=True) #Read repeatedly from data00 to data09
    im.set_data(r, sd)
    return im,

ani = FuncAnimation(fig, update_anim, interval=500, blit=True, frames = filenum, repeat_delay=100)

#Save
ani.save("anime.gif", writer="pillow")

#display
plt.show()

reference: Flexible animation creation using animation.FuncAnimation of matplotlib

Now you can draw beautiful animations with matplotlib.