matplotlib官方例子fig.gca(projection='3d')报错

错误如下

KeyError                                  Traceback (most recent call last)
C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\projections\__init__.py in get_projection_class(projection)
     57     try:
---> 58         return projection_registry.get_projection_class(projection)
     59     except KeyError:

C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\projections\__init__.py in get_projection_class(self, name)
     24         """
---> 25         return self._all_projection_types[name]
     26 

KeyError: '3d'

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
<ipython-input-1-102b5d3e8d3a> in <module>
      5 
      6 fig = plt.figure()
----> 7 ax = fig.gca(projection='3d')
      8 
      9 # Make data.

C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\figure.py in gca(self, **kwargs)
   1930 
   1931         # no axes found, so create one which spans the figure
-> 1932         return self.add_subplot(1, 1, 1, **kwargs)
   1933 
   1934     def sca(self, a):

C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\figure.py in add_subplot(self, *args, **kwargs)
   1394         else:
   1395             projection_class, kwargs, key = \
-> 1396                 self._process_projection_requirements(*args, **kwargs)
   1397 
   1398             # try to find the axes with this key in the stack

C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\figure.py in _process_projection_requirements(self, polar, projection, *args, **kwargs)
   1118 
   1119         if isinstance(projection, str) or projection is None:
-> 1120             projection_class = projections.get_projection_class(projection)
   1121         elif hasattr(projection, '_as_mpl_axes'):
   1122             projection_class, extra_kwargs = projection._as_mpl_axes()

C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\projections\__init__.py in get_projection_class(projection)
     58         return projection_registry.get_projection_class(projection)
     59     except KeyError:
---> 60         raise ValueError("Unknown projection %r" % projection)
     61 
     62 

ValueError: Unknown projection '3d'

解决办法：

from mpl_toolkits.mplot3d import Axes3D