我已经安装了anaconda并安装了matplotlib，一切正常。但是一旦我使用here
conda install -c anaconda nccl安装了nccl，
在下一次之后，我无法导入matplotlib，出现以下错误：
>>> import matplotlib.pyplot as plt
Traceback (most recent call last): File "<stdin>", line 1, in <module> File
"/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/__init__.py",
line 1111, in <module>
rcParamsOrig = RcParams(rcParams.copy()) File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/__init__.py",
line 891, in __getitem__
from matplotlib import pyplot as plt File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/pyplot.py",
line 32, in <module>
import matplotlib.colorbar File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/colorbar.py",
line 40, in <module>
import matplotlib._constrained_layout as constrained_layout File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/_constrained_layout.py",
line 52, in <module>
from matplotlib.legend import Legend File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/legend.py",
line 43, in <module>
from matplotlib.offsetbox import HPacker, VPacker, TextArea, DrawingArea File
"/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/offsetbox.py",
line 33, in <module>
from matplotlib.image import BboxImage File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/image.py",
line 19, in <module>
from matplotlib.backend_bases import FigureCanvasBase File "/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/backend_bases.py",
line 46, in <module>
from matplotlib import ( ImportError: cannot import name 'get_backend' from 'matplotlib'
(/home/rofelia/anaconda3/envs/pytorch04/lib/python3.7/site-packages/matplotlib/__init__.py)
我无法找到解决方案。请帮帮我。谢谢。