Bug in visualize

[zyb19960609]

Traceback (most recent call last):
File "/home/zly/data/zhangyanbo/social-lstm-master/validation.py", line 775, in
main()
File "/home/zly/data/zhangyanbo/social-lstm-master/validation.py", line 765, in main
args.max_ped_ratio, results[i][5], [min_r, max_r, plot_offset], 20)
File "/home/zly/data/zhangyanbo/social-lstm-master/validation.py", line 410, in plot_trajectories
colors, name, frames, true_target_id_values, plot_directory, style, num_of_color)
File "/home/zly/data/zhangyanbo/social-lstm-master/validation.py", line 482, in create_plot_animation
ani.save(plot_directory + '/' + name + '.mp4')
File "/home/zly/anaconda3/lib/python3.6/site-packages/matplotlib/animation.py", line 1200, in save
writer.grab_frame(**savefig_kwargs)
File "/home/zly/anaconda3/lib/python3.6/contextlib.py", line 99, in exit
self.gen.throw(type, value, traceback)
File "/home/zly/anaconda3/lib/python3.6/site-packages/matplotlib/animation.py", line 241, in saving
self.finish()
File "/home/zly/anaconda3/lib/python3.6/site-packages/matplotlib/animation.py", line 367, in finish
self.cleanup()
File "/home/zly/anaconda3/lib/python3.6/site-packages/matplotlib/animation.py", line 405, in cleanup
out, err = self._proc.communicate()
File "/home/zly/anaconda3/lib/python3.6/subprocess.py", line 863, in communicate
stdout, stderr = self._communicate(input, endtime, timeout)
File "/home/zly/anaconda3/lib/python3.6/subprocess.py", line 1525, in _communicate
selector.register(self.stdout, selectors.EVENT_READ)
File "/home/zly/anaconda3/lib/python3.6/selectors.py", line 351, in register
key = super().register(fileobj, events, data)
File "/home/zly/anaconda3/lib/python3.6/selectors.py", line 237, in register
key = SelectorKey(fileobj, self._fileobj_lookup(fileobj), events, data)
File "/home/zly/anaconda3/lib/python3.6/selectors.py", line 224, in _fileobj_lookup
return _fileobj_to_fd(fileobj)
File "/home/zly/anaconda3/lib/python3.6/selectors.py", line 39, in _fileobj_to_fd
"{!r}".format(fileobj)) from None
ValueError: Invalid file object: <_io.BufferedReader name=9>

[quancore]

In the test environment, it was working. The error could be related to a version of a package. Feel free to submit a PR if needed.