[error reported] [Python] [Matplotlib] importerror: failed to import any QT binding

error message

ImportError: Failed to import any qt binding

complete error message:

Traceback (most recent call last):
  File "/home/xovee/Desktop/codes/www20/plot/cascade_plot.py", line 1, in <module>
    import matplotlib.pyplot as plt
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/pyplot.py", line 2355, in <module>
    switch_backend(rcParams["backend"])
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/pyplot.py", line 221, in switch_backend
    backend_mod = importlib.import_module(backend_name)
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/backends/backend_qt4agg.py", line 5, in <module>
    from .backend_qt5agg import (
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/backends/backend_qt5agg.py", line 11, in <module>
    from .backend_qt5 import (
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/backends/backend_qt5.py", line 15, in <module>
    import matplotlib.backends.qt_editor.figureoptions as figureoptions
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/backends/qt_editor/figureoptions.py", line 13, in <module>
    from matplotlib.backends.qt_compat import QtGui
  File "/home/xovee/miniconda3/envs/tf-2.0-a0/lib/python3.6/site-packages/matplotlib/backends/qt_compat.py", line 158, in <module>
    raise ImportError("Failed to import any qt binding")
ImportError: Failed to import any qt binding

environment