问VSCode无法切换matplotlib后端: ImportError:无法加载需要'qt5‘交互框架的后端'Qt5Agg’

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(base) user@user:~/test$ export MPLBACKEND=Qt5Agg
(base) user@user:~/test$ python
Python 3.8.3 (default, Jul  2 2020, 16:21:59) 
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import matplotlib
>>> print("Using:",matplotlib.get_backend())
Using: Qt5Agg
>>> import matplotlib.pyplot as plt
>>> plt.plot([1,2,3], [10, 20, 30])
[<matplotlib.lines.Line2D object at 0x7fe26b403d00>]
>>> plt.show()
>>> print("Using:",matplotlib.get_backend())
Using: agg
>>> plt.switch_backend('Qt5Agg')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/zslwyuan-laptop/anaconda3/lib/python3.8/site-packages/matplotlib-3.3.0rc1+627.gff821ba32-py3.8-linux-x86_64.egg/matplotlib/pyplot.py", line 268, in switch_backend
    raise ImportError(
ImportError: Cannot load backend 'Qt5Agg' which requires the 'qt5' interactive framework, as 'headless' is currently running
>>>