我想在Jupyter中导入from sklearn.tree import DecisionTreeRegressor，但当我运行包含上述导入的代码行时，出现了这个错误。

<ipython-input-16-28b3e81cd98d> in <module>----> 1 from sklearn.tree import DecisionTreeRegressor~/.local/lib/python3.6/site-packages/sklearn/tree/__init__.py in <module>      4 """      5 ----> 6 from ._classes import BaseDecisionTree      7 from ._classes import DecisionTreeClassifier      8 from ._classes import DecisionTreeRegressor~/.local/lib/python3.6/site-packages/sklearn/tree/_classes.py in <module>     38 from ..utils.validation import check_is_fitted     39 ---> 40 from ._criterion import Criterion     41 from ._splitter import Splitter     42 from ._tree import DepthFirstTreeBuilder~/.local/lib/python3.6/site-packages/sklearn/tree/_criterion.cpython-36m-x86_64-linux-gnu.so in init sklearn.tree._criterion()AttributeError: type object 'sklearn.tree._criterion.array' has no attribute '__reduce_cython__'

我尝试通过conda安装scipy并更新scikit-learn，但问题没有解决。

回答：

尝试更新Cython：

pip install cython