Python 保存 Matplotlib 动画
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Save Matplotlib Animation
提问by throwaway17434
I am trying to make an Animation of a wave package and save it as a movie. Everything except the saving is working. Can you please tell me what I am doing wrong? When going into the line ani.save('MovWave.mp4')he tells me:
我正在尝试制作 wave 包的动画并将其另存为电影。除了保存之外的一切都在工作。你能告诉我我做错了什么吗？排队时，ani.save('MovWave.mp4')他告诉我：
writer = writers.list()[0]
IndexError: list index out of range
I tried googling it of course, but I don't even know what it means.
我当然尝试过谷歌搜索，但我什至不知道它是什么意思。
UPDATE:I can call ffmpegin console now. It says I have ffmpeg version 0.10.7-6:0.10.7-0jon1~preciseinstalled. I updated the code and ran the program, but now I get the following error:
更新：我ffmpeg现在可以在控制台中调用。它说我安装了 ffmpeg 版本0.10.7-6:0.10.7-0jon1~precise。我更新了代码并运行了程序，但现在出现以下错误：
Traceback (most recent call last):
ani.save('MovWave.mpeg', writer="ffmpeg")
writer.grab_frame()
dpi=self.dpi)
self.canvas.print_figure(*args, **kwargs)
self.figure.dpi = origDPI
self.dpi_scale_trans.clear().scale(dpi, dpi)
self._mtx = np.identity(3)
from numpy import eye
File "<frozen importlib._bootstrap>", line 1609, in _handle_fromlist
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte
Update 2:Apparently there is a bug when using python 3.3 as doctorlove pointed out. I am now trying to use python 2.7 instead. Now it creates an mpeg-file but it cannot be played and it is only about ~150 kB big.
更新 2：显然在使用 python 3.3 时存在一个错误，正如doctorlove 指出的那样。我现在尝试改用 python 2.7。现在它创建了一个 mpeg 文件，但无法播放，它只有大约 150 kB 大。
Update 3:Okay, so I tried the exact same code on my Win7 machine and it also works in python 3.3. But I have the same problem, I had earlier with python 2.7. The mpeg-file created cannot be played and is only a few hundred kB.
更新 3：好的，所以我在我的 Win7 机器上尝试了完全相同的代码，它也适用于 python 3.3。但是我有同样的问题，我之前在 python 2.7 上遇到过。创建的mpeg文件无法播放，只有几百kB。
#! coding=utf-8
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import time
time.clock()
def FFT(x,y):
X = (x[-1]-x[0])/len(y)
f = np.linspace(-2*np.pi/X/2,2*np.pi/X/2,len(y))
F = np.fft.fftshift(np.fft.fft(y))/np.sqrt(len(y))
return(f,F)
def FUNCTION(k_0,dx,c,t):
y = np.exp(1j*k_0*(x-c*t))*np.exp(-((x-c*t)/(2*dx))**2 )*(2/np.pi/dx**2)**(1/4)
k,F = FFT((x-c*t),y)
return(x,y,k,F)
#Parameter
N = 1000
x = np.linspace(0,30,N)
k_0 = 5
dx = 1
c = 1
l = [k_0,c,dx]
fig = plt.figure("Moving Wavepackage and it's FFT")
sub1 = plt.subplot(211)
sub2 = plt.subplot(212)
sub2.set_xlim([-10,10])
sub1.set_title("Moving Wavepackage and it's FFT")
sub1.set_ylabel("$Re[\psi(x,t)]$")
sub1.set_xlabel("$t$")
sub2.set_ylabel("$Re[\psi(k_x,t)]$")
sub2.set_xlabel("$k_x$")
n = 50
t = np.linspace(0,30,n)
img = []
for i in range(n):
x,y,k,F = FUNCTION(k_0,dx,c,t[i])
img.append(plt.plot(x,np.real(y),color="red", axes=plt.subplot(211)))
img.append(plt.plot(k,np.real(F),color="red", axes=plt.subplot(212)))
ani = animation.ArtistAnimation(fig, img, interval=20, blit=True, repeat_delay=0)
ani.save('MovWave.mpeg', writer="ffmpeg")
print(time.clock())
plt.show()
回答by doctorlove
You mentioned mencoderin your text, but not the code.
您mencoder在文本中提到了，但没有在代码中提到。
Matplotlib docs has a check for mencoderin a demo:
Matplotlib 文档mencoder在演示中进行了检查：
not_found_msg = """
The mencoder command was not found;
mencoder is used by this script to make an avi file from a set of pngs.
It is typically not installed by default on linux distros because of
legal restrictions, but it is widely available.
"""
try:
subprocess.check_call(['mencoder'])
except subprocess.CalledProcessError:
print "mencoder command was found"
pass # mencoder is found, but returns non-zero exit as expected
# This is a quick and dirty check; it leaves some spurious output
# for the user to puzzle over.
except OSError:
print not_found_msg
sys.exit("quitting\n")
