python - 保存 Matplotlib 动画

Question

我正在尝试制作波浪包的动画并将其保存为电影。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？当进入 ani.save('MovWave.mp4') 行时，他告诉我:

    writer = writers.list()[0]
IndexError: list index out of range

当然，我尝试用谷歌搜索它，但我什至不知道它是什么意思。

更新:我现在可以在控制台中调用 ffmpeg。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

更新 2: 正如 doctorlove 指出的那样，显然在使用 python 3.3 时存在错误。我现在正在尝试改用 python 2.7。现在它创建了一个 mpeg 文件，但无法播放，而且只有大约 150 kB 大。

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。但我有同样的问题，我之前使用 python 2.7。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()

Answer 1

您在文本中提到了 mencoder，但没有提到代码。

Matplotlib 文档在 demo 中检查了 mencoder :

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")