「つくりながら学ぶ！深層強化学習」の3章P.79にて、動画の描画関数でTypeErrorが出ます。

前提・実現したいこと

「つくりながら学ぶ！深層強化学習」の3章P.79にて、動画の描画関数でTypeErrorが出ます。
本書(https://book.mynavi.jp/manatee/detail/id=88961)や参考URL(https://nbviewer.jupyter.org/github/patrickmineault/xcorr-notebooks/blob/master/Render%20OpenAI%20gym%20as%20GIF.ipynb)にも詳細な内容が書かれていないため、エラーの原因がよくわかりません。
どのようにして対処すればいいのか、ご教授いただきたいです。
よろしくお願いします。

発生している問題・エラーメッセージ

TypeError Traceback (most recent call last)
<ipython-input-1-c6ee8c27c8b9> in <module>
34 observation, reward, done, info = env.step(action)
35
---> 36 display_frames_as_gif(frames)

<ipython-input-1-c6ee8c27c8b9> in display_frames_as_gif(frames)
22 anim = animation.FuncAnimation(plt.gcf(), animate, frames = len(frames), interval=50)
23 anim.save('movie_cartpole.mp4') # 追記：動画の保存です
---> 24 display(display_animation(anim, default_mode='loop'))
25
26

~\Anaconda3\lib\site-packages\JSAnimation\IPython_display.py in display_animation(anim, **kwargs)
84 """Display the animation with an IPython HTML object"""
85 from IPython.display import HTML
---> 86 return HTML(anim_to_html(anim, **kwargs))
87
88

~\Anaconda3\lib\site-packages\JSAnimation\IPython_display.py in anim_to_html(anim, fps, embed_frames, default_mode)
74 anim.save(f.name, writer=HTMLWriter(fps=fps,
75 embed_frames=embed_frames,
---> 76 default_mode=default_mode))
77 html = open(f.name).read()
78

~\Anaconda3\lib\site-packages\matplotlib\animation.py in save(self, filename, writer, fps, dpi, codec, bitrate, extra_args, metadata, extra_anim, savefig_kwargs, progress_callback)
1154 progress_callback(frame_number, total_frames)
1155 frame_number += 1
-> 1156 writer.grab_frame(**savefig_kwargs)
1157
1158 # Reconnect signal for first draw if necessary

~\Anaconda3\lib\contextlib.py in exit(self, type, value, traceback)
117 if type is None:
118 try:
--> 119 next(self.gen)
120 except StopIteration:
121 return False

~\Anaconda3\lib\site-packages\matplotlib\animation.py in saving(self, fig, outfile, dpi, *args, **kwargs)
230 yield self
231 finally:
--> 232 self.finish()
233
234

~\Anaconda3\lib\site-packages\matplotlib\animation.py in finish(self)
526 # are available to be assembled.
527 self._run()
--> 528 MovieWriter.finish(self) # Will call clean-up
529
530 def cleanup(self):

~\Anaconda3\lib\site-packages\matplotlib\animation.py in finish(self)
365 def finish(self):
366 '''Finish any processing for writing the movie.'''
--> 367 self.cleanup()
368
369 def grab_frame(self, **savefig_kwargs):

~\Anaconda3\lib\site-packages\matplotlib\animation.py in cleanup(self)
529
530 def cleanup(self):
--> 531 MovieWriter.cleanup(self)
532
533 # Delete temporary files

~\Anaconda3\lib\site-packages\matplotlib\animation.py in cleanup(self)
397 self._frame_sink().close()
398 # Use the encoding/errors that universal_newlines would use.
--> 399 out = TextIOWrapper(BytesIO(out)).read()
400 err = TextIOWrapper(BytesIO(err)).read()
401 if out:

TypeError: a bytes-like object is required, not 'str'

該当のソースコード

Python
1
2import numpy as np
3import matplotlib.pyplot as plt
4%matplotlib inline
5import gym
6
7from JSAnimation.IPython_display import display_animation
8from matplotlib import animation
9from IPython.display import display
10
11def display_frames_as_gif(frames):
12    """
13    Displays a list of frames as a gif, with controls
14    """
15    plt.figure(figsize=(frames[0].shape[1]/72.0, frames[0].shape[0]/72.0),
16               dpi=72)
17    patch = plt.imshow(frames[0])
18    plt.axis('off')
19 
20    def animate(i):
21        patch.set_data(frames[i])
22
23 
24    anim = animation.FuncAnimation(plt.gcf(), animate, frames = len(frames), interval=50)
25    anim.save('movie_cartpole.mp4')  # 追記：動画の保存です
26    display(display_animation(anim, default_mode='loop'))
27    
28
29frames = []
30env = gym.make('CartPole-v0')
31observation = env.reset()
32
33for step in range(0,200):
34    frames.append(env.render(mode='rgb_array'))
35    action = np.random.choice(2)
36    observation, reward, done, info = env.step(action)
37    
38display_frames_as_gif(frames)
39