Matplotlib 错误发生在我第一次运行 Jupyter 单元格时，但不会发生第二次

Question

第一次，但不是后续，我运行这个代码块，我得到一个错误。谁能帮我理解为什么请？

以前根本没有关于此错误的SO帖子(至少在搜索结果中(

我对编码相当陌生。据我所知，这是我代码中的序列错误。也就是说，第一次(尚未(加载属性时，该属性将进一步加载到代码块的下方，使其在我再次运行代码时可用。问题是我无法弄清楚它是代码的哪一部分。

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
%matplotlib notebook
def data_gen(t=0):
cnt = 0
while cnt < 150:
cnt += 1
t += 0.1
yield t, np.sin(2*np.pi*t) * np.exp(-t/10.)

def init():
ax.set_ylim(-1.1, 1.1)
ax.set_xlim(0, 10)
del xdata[:]
del ydata[:]
line.set_data(xdata, ydata)
return line,
fig, ax = plt.subplots()
line, = ax.plot([], [], lw=2)
ax.grid()
xdata, ydata = [], []

def run(data):
# update the data
t, y = data
xdata.append(t)
ydata.append(y)
xmin, xmax = ax.get_xlim()
if t >= xmax:
ax.set_xlim(xmin, 2*xmax)
ax.figure.canvas.draw()
line.set_data(xdata, ydata)
return line,
ani = animation.FuncAnimation(fig, run, data_gen, blit=False, interval=15,
repeat=False, init_func=init)                                   
plt.show()

错误信息

> Traceback (most recent call last):   File
> "/Users/alexfreeman/Documents/Dev/AnacondaInstall/anaconda/envs/py3-env/lib/python3.6/site-packages/matplotlib/cbook/__init__.py",
> line 387, in process
>     proxy(*args, **kwargs)   File "/Users/alexfreeman/Documents/Dev/AnacondaInstall/anaconda/envs/py3-env/lib/python3.6/site-packages/matplotlib/cbook/__init__.py",
> line 227, in __call__
>     return mtd(*args, **kwargs)   File "/Users/alexfreeman/Documents/Dev/AnacondaInstall/anaconda/envs/py3-env/lib/python3.6/site-packages/matplotlib/animation.py",
> line 1499, in _stop
>     self.event_source.remove_callback(self._loop_delay) AttributeError: 'NoneType' object has no attribute 'remove_callback'

Answer 1

显然，导入matplotlib.pyplot和设置后端notebook顺序很重要。

将%matplotlib notebook线放在顶部时，对我来说效果很好

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