导入错误：无法导入名称“_safe_split”

当我尝试使用 train_test_split 函数时出现以下错误。然后我尝试安装scipy，但没有帮助。有谁知道我可能从下面的错误中遗漏了哪些内容？谢谢！

ImportError                               Traceback (most recent call last)
<ipython-input-53-57bf27feca45> in <module>()
      1 import numpy as np
----> 2 from sklearn.model_selection import train_test_split
      3 
      4 X_train, X_test, y_train, y_test = train_test_split(X, Y, test_size=0.33, random_state=42)

/usr/local/lib/python3.4/dist-packages/sklearn/model_selection/__init__.py in <module>()
     15 from ._split import check_cv
     16 
---> 17 from ._validation import cross_val_score
     18 from ._validation import cross_val_predict
     19 from ._validation import learning_curve

/usr/local/lib/python3.4/dist-packages/sklearn/model_selection/_validation.py in <module>()
     25 from ..utils.fixes import astype
     26 from ..utils.validation import _is_arraylike, _num_samples
---> 27 from ..utils.metaestimators import _safe_split
     28 from ..externals.joblib import Parallel, delayed, logger
     29 from ..metrics.scorer import check_scoring

ImportError: cannot import name '_safe_split'

奇怪的是：升级到 scikit 版本到 0.18.1 后出现此错误

我重新启动了 python 控制台，它解决了我的问题。